Plasmodium infection develop genetic mechanisms of protection against severe disease. The clinical manifestation of malaria results primarily from the lysis of infected erythrocytes and subsequent immune and inflammatory responses. Herein, we review the genetic alterations associated with erythrocytes or mediators of the immune system, which might influence malaria outcome. Moreover, polymorphisms in genes related to molecules involved in mechanisms of cytoadherence and their influence on malaria pathology are also discussed. The results of some studies have suggested that the combinatorial effects of a set of genetic factors in the erythrocyte-immunology pathway might be relevant to host resistance or susceptibility against Plasmodium infection. However, these results must be interpreted with caution because of the differences observed in the functionality and frequency of polymorphisms within different populations. With the recent advances in molecular biology techniques, more robust studies with reliable data have been reported, and the results of these studies have identified individual genetic factors for consideration in preventing severe disease and the individual response to treatment.Populations exposed to  Plasmodium infection per year [Plasmodium  are responsible for almost all human infections [Malaria is one of the most important and prevalent infectious diseases in the world. The World Health Organization (WHO) estimated 225 million malaria cases worldwide with 781,000 deaths due to Malaria has been associated to gene selective pressure in the human genome, and it has been associated as an evolutionary force of some genetic diseases, such as sickle cell disease (SCD), thalassemia, glucose-6-phosphate dehydrogenase (G6PD) deficiency, and other red blood cell (RBC) genetic anemia with Mendelian inheritance. Haldane 1949) suggested a “balanced polymorphism” where the hemoglobin S (HbS) homozygote disadvantage is recompensed through the resistance of the heterozygote (HbAS) in regions where malaria is endemic . Reports9 suggestPlasmodium inside the RBC and its subsequent rupture have been implicated in several phenomena present in the malarial syndrome. A protective effect against malaria infection has been associated with genetic disorders involving the RBC, such as cytoskeleton disorders, surface antigen gene mutations, enzymatic machinery deficiencies, or hemoglobin alterations [ Plasmodium infection, and the balance between proinflammatory (Th1-type) and anti-inflammatory (Th2-type) cytokines has been implicated in both the control of parasite multiplication and the development of symptoms. The genetic background of the affected individual might also influence cytokine expression and disease outcomes [Genetic epidemiology may help in pointing out major molecular pathways of some infectious diseases, such as malaria, which involve a robust immune and inflammatory response and the participation of erythrocytes and other blood cells in its pathogenesis. The aim of this paper is to review the major genetic alterations in the human host associated with the clinical spectrum of malaria infection and disease development. We specifically address the areas of inherited disorders in red blood cells (RBC) and mutations in the genes of key molecules during the immune response that confer an increase of susceptibility or resistance against malaria. The multiplication of erations . The immoutcomes , 7. NotaUnderstanding the genetic alterations involving RBC disorders and the immune response might provide insight into the development of new strategies for host-genotype treatment and/or the prevention of malaria.P. falciparum in humans and P. knowlesi in experimental models [SLC4A1Δ27) in the erythrocyte membrane [P. falciparum merozoites invasion [Several membrane-inherited disorders of RBC provide additional information concerning the pathogenesis of malaria. Hereditary spherocytosis is a disorder characterized by the loss of membrane lipid surface. This common hemolytic anemia also reflects ineffective integral protein interactions and is associated with lower parasitemia . Other Rl models . Howevermembrane . Althougmembrane . SAO ovainvasion . Patientinvasion –13. DARC human gene that is considered to be a nonspecific receptor for several chemokines. The P. vivax merozoite uses the Fy antigen to invade RBC [Fy antigen possesses two distinct alleles known as Fya and Fyb, which result from a single point mutation in codon 42 (rs2814778) that results in a glycine to asparagine substitution within the protein. Another polymorphism  in the promoter region of the DARC gene ablates DARC expression on the surface of erythrocytes. Erythrocytes expressing Fya exhibited 41–50% lower binding to P. vivax compared with Fyb, and individuals with the Fya+b-phenotype showed a 30–80% lower risk of developing clinical symptoms of vivax malaria [Fy-33 genotype are not susceptible to P. vivax merozoites invasion and are refractory to the erythrocytic stage of the disease. However, the hepatic malaria stage has been observed in these individuals, making them reservoirs for the disease [P. falciparum infection, more than one receptor on the surface of RBC is responsible for merozoite infection, which include glycophorin A, B, and C , protein band 3 and others , whose molecular identity has not yet been determined [band 3 or ΥPCG gene are highly prevalent in malaria endemic areas (Papua New Guinea) and confer resistance to severe diseases [ΥPAG and ΥPBG, have been shown to confer only partial protection against the Plasmodium invasion of RBC [ΥPBG receptor gene (rs7683365) was associated with host susceptibility to P. falciparum infection [The Duffy, also called Duffy antigen/chemokine receptor (DARC), Fy glycoprotein, or CD234, is a RBC antigen encoded by the vade RBC . The Fy  malaria . The RBCn 42 rs28778 that termined . The gendiseases . Polymorn of RBC , 19. Furnfection .G6PD gene is located on the X chromosome and is therefore more prevalent in men [G6PD B (wild type), G6PD A (nondeficient type), and G6PD A- (African deficient type) [PK gene is highly pleomorphic and includes 59 SNPs and several loss-of-function variants that might be associated with decreased resistance to malaria [The G6PD deficiency and low levels of pyruvate kinase are the most prevalent genetic alterations in RBC that can influence malaria outcomes. G6PD is a metabolic enzyme that catalyzes the first reaction in the pentose phosphate pathway, providing energy for the RBC in the form of nicotinamide adenine dinucleotide phosphate (NADPH). NADPH enables RBC to counterbalance oxidative stress through oxidant agents . The G6Pt in men . The G6Pt in men . Approxint type) . It has nt type) . Moreovent type) , 25. Anont type) . PK defint type) . PK cata malaria .Hemoglobin (Hb), the main compound of erythrocytes, is a tetrameric protein that consists of two pairs of unlike globin chains; each globin chain is associated with one prosthetic group, called a heme group. Hemoglobinopathies are inherited disorders of Hb that can be classified into two major groups. The first group involves structural alterations or variants of Hb, such as HbS, HbC, and HbE; the second group of hemoglobinopathies is classified as synthesis defects of Hb and has been associated with a decrease or absence of globin chain synthesis, with the most common alteration related to the alpha and beta-globin chains .alpha-globin genes (HBA1 and HBA2), located on chromosome 16 [+-thal, and there is unique potential for a rightward crossover between the HBA genes. One study reported that alpha+-thal increased the incidence of mild malaria [+-thal was associated with a reduced risk of uncomplicated malaria episodes [The alpha-thalassemia  is the most common genetic disorder in the human population and is caused by the decreased or absent synthesis of the alpha globin chain due to the deletion or nondeletion mutation of one or both osome 16 , 29. A 3 malaria . Howeverepisodes  or a proepisodes –35. beta-globin gene (HBB) of the human globin gene cluster located on chromosome 11 [P. falciparum malaria [Beta-thalassemia is characterized by the decreased synthesis of the beta-globin chain through a genetic alteration in the osome 11 . The het malaria  and prot malaria . beta-globin gene (HBB) is associated with a structural modification of the beta polypeptide chain Glu6Val (HbS), resulting in the variant HbS, which can be found in the asymptomatic heterozygous state. This variant is commonly known as the sickle cell trait (HbAS). In 1978, Friedman suggested that the mechanism of resistance against Plasmodium of RBC with HbS might be solely due to intraerythrocytic conditions [ATP2B4 gene, which encodes the main calcium pump of erythrocytes; and the other locus was indicated by an SNP on chromosome 16q22.2, possibly linked to a gene encoding the tight-junction MARVELD3, which may have a role in microvascular damage caused by endothelial adherence of parasitized erythrocytes [The presence of a single nucleotide mutation (rs334) in the nditions . HbS polnditions , 41. Thenditions , 43. Mannditions , 45. A lnditions . Howevernditions . Moreovenditions . One of hrocytes . Hemoglobin C (HbC) occurs from a point mutation leading to a Glu6Lys substitution at the sixth position in the beta-globin polypeptide chain (rs33930165) , and hemGenetic alterations in erythrocytes were probably the first to be discovered as a result of the evolutionary pressure of malaria in the human genome. Mutations affecting several protection mechanisms related to RBC have been described for HbS . FurtherPlasmodium is responsible for the degradation of 60% to 80% of the total Hb [Plasmodium has developed a series of protective mechanisms against the deleterious effects of free heme through the polymerization of heme in hemozoin, a malarial pigment that counteracts the pro-oxidative effects of iron (Fe) present in protoporphyrin IX [β) of Hp is approximately 40 kDa, and the alpha 1 chain (α1), which is synthesized by the allele variant Hp1, is approximately 8.86 kDa and is subdivided into 1S and 1F; the alpha 2 chain (α2), which is synthesized by the allele variant Hp2, is approximately 17.3 kDa [Hp1.1 > Hp1.2 > Hp2.2) and for CD163 (Hp2.2 > Hp1.2 > Hp1.1) [Hp2.2 genotype has been associated with increased iron redox activity and oxidative stress compared with the Hp1.1 genotype [Hp2.2 has been associated with an increased susceptibility to various inflammatory conditions, including malaria. We have recently reported that subjects with the Hp2.2 genotype display a higher risk of developing symptomatic mild malaria (as opposed to asymptomatic) upon Plasmodium infection [During the erythrocytic stage of malaria, merozoites multiply inside RBC, which result in the rupture of this structure and subsequent release of free Hb into the circulating blood. In the presence of reactive oxygen species (ROS), Hb releases its heme prosthetic group. In addition, the total Hb . Hb degrtotal Hb . Free hetotal Hb , and celtotal Hb . The Plahyrin IX . The hos17.3 kDa . These agenotype , 63. Furgenotype . Thus, tnfection .HMOX1 gene, which is associated with the increased or decreased synthesis of HO-1 in response to different stimuli [HMOX1 gene is associated with a greater chance of developing severe malaria, suggesting that the increased expression of HO-1 is deleterious for human malaria [HMOX1 gene polymorphism have greater susceptibility to developing malaria and higher inflammatory scores than individuals with the short form [Plasmodium infection. Sickle Hb induces the expression of HO-1, which leads to CO production. CO binds with high affinity to free Hb and prevents the release of heme from hemoglobin, which reduces systemic levels of deleterious free heme [HMOX1 gene polymorphisms have been described, which correspond to the single nucleotide polymorphisms −1135G>A (no rs designation available) and −413A>TG (no rs designation available). However, only the last SNP seems to have functional importance [The induction of HO-1 in experimental models of malaria has been associated with increased resistance to malaria as a result of HO-1 in controlling heme-induced nonspecific tissue damage and inflammation , 66. The stimuli . Individ stimuli . This po stimuli –73, but  malaria , 75. We ort form . Howeverree heme , 66. Othportance .β from mononuclear cells through superoxide dismutase-1 (SOD-1), an enzyme responsible for the detoxification of harmful superoxide [P. vivax with higher sensitivity and sensibility than TNF-α levels [SOD-1 gene and different expressions of this enzyme in subjects with malaria. Furthermore, those SOD-1 SNPs were associated with malaria symptoms in individuals infected with P. vivax, indicating that the genetic predisposition of the individual might alter the response of these subjects against ROS.Heme reduces the production of prostaglandin E2 (PGE2) and TGF-peroxide . SOD-1 iα levels , confirmP. falciparum glycosylphosphatidylinositol (GPI), while TLR9 has been reported to recognize Plasmodium DNA or the hemozoin pigment [Toll-like receptors are a family of transmembrane proteins present in monocytes, macrophages, and dendritic cells, which play a key role in the innate immune response. TLR recognize pathogen associated molecular patterns (PAMPs) through extracellular receptor modules and initiate the inflammatory cascade through the transcription of inflammatory cytokines, type 1 interferon, and chemokines through NF-kB or interferon regulatory factor dependent pathways , 79. Fur pigment –87. TLR genes are functionally important and affect the recognition of ligands and intracellular signaling. These SNPs have been associated with numerous infectious and parasitic diseases [TLR gene polymorphisms with clinical malaria and parasitemia levels. Two polymorphisms have been described in the 5′ untranslated region (UTR) of the TLR2 gene, a 22-base pair deletion in the first untranslated exon (Δ22), and an (GT)n dinucleotide repeat in the second intron [TLR2  were not identified in the Plasmodium-infected population [TLR4 gene, the more frequent genetic alterations studied were two nonsynonymous cosegregating SNPs  that modify the ligand-binding site of the receptor [TLR4 Asp299Gly was associated with an increased risk of maternal anemia and infant low-birth weight in pregnant women with malaria [TLR4 Asp299Gly and 2.6-fold with TLR4 Thr399Ile [Some common SNPs in diseases . Severald intron . Both pod intron . Howeverd intron . Other Spulation . In the receptor . The TLR malaria . In addihr399Ile . TLR9 gene has been associated with the pathogenesis of severe malaria in humans and experimental models. Studies have demonstrated that TLR9-deficient mice survived more during cerebral malaria and that the antagonist-mediated TLR9 inhibition conferred protection against cerebral malaria in mice [TLR9 gene showed an increased risk of low birth weight among infants from pregnant women with malaria, whereas increased parasitemia was observed in adults with mild malaria [TLR9 gene, rs187084 (−1486C>T), rs5743836 (1237C>T), rs352139 (1174G>A), and rs352140 (2848G>A), were not associated with severe malaria [TLR9 gene polymorphisms might be associated with a milder form of the disease [TIRAP gene  has been associated with both protection against malaria [TIRAP gene polymorphism with malaria remains controversial.The  in mice , 96. A h malaria , 94. How malaria . Smaller disease , 99. The disease . An SNP  malaria  and susc malaria , but theTLR and their signaling pathways remain controversial. Thus far, no conclusive evidence of polymorphisms in these receptors that might influence the disease outcome and effect host-genotype treatment have been identified.The importance of TLR in malaria infection has been recently described, particularly with regard to TLR2, 4, and 9. Genetic alterations in α) are critical for controlling the erythrocytic and hepatic stages of Plasmodium infection [Malaria infection is marked by changes in cytokine expression resulting from individual immune responses. Proinflammatory Th1-type cytokines  and TNF −238G>A (rs361525) were associated with an increased risk of cerebral malaria and severe malarial anemia, respectively [TNF −308G>A polymorphism with a shorter interval to malaria reinfection and the TNF −238G>A polymorphism with protection against mild symptomatic malaria [TNF −308A allele was associated with severe malaria and other infections [TNFPD allele haplotype  was associated with increased susceptibility to cerebral malaria because the transcription factor OCT-1 binds to TNF −857T in the TNFPD allele but not to TNF −857C in the TNFPA, B and C alleles and interacts with the proinflammatory NF-κB subunit transcription factor p65 at the adjacent binding site [TNF gene polymorphisms and severe malaria in Kenya, Malawi, Mali, Tanzania, and Indonesia [LTA polymorphisms may influence resistance to malaria in humans, and two SNPs have been described: LTA C+80A (rs2239704) and LTA A+252G (rs909253). The first is an SNP that allows specific binding of the transcriptional repressor ABF-1 and, therefore, considered to be a low LTa-producing allele, has been associated with lower P. falciparum parasitemia in malaria-endemic Burkina Faso but was not associated with severe malaria in Gambia [TNF-ications . High co malaria , 107. Hoasitemia , 109. Geectively , 111. St malaria . In Sri fections . In anoting site . Other sndonesia –117. It ndonesia . Since Ln Gambia –120. Then Gambia , but it n Gambia . Both SNn Gambia .Plasmodium infection [immunologically active interferon regulatory factor-1 [The chromosomal region 5q31–33 contains several important genes encoding molecules, such as cytokines, growth factors, and growth factor receptors, which are involved in immunity against nfection . The 5q3factor-1 . Concernfactor-1 , 125. Asfactor-1 . A genomfactor-1 . Furtherfactor-1 .γ, which activates macrophages to destroy parasitized erythrocytes, promotes the production of opsonizing antibodies, and helps to destroy parasites during the hepatic cycle [γ also has proinflammatory effects that may contribute to disease severity [IFNG gene polymorphisms and susceptibility to disease. The first intron of the IFNG gene contains a highly polymorphic CA-repeat microsatellite, whose 12 CA-repeat allele is associated with high levels of IFN-γ production in vitro [IFNG+874T (rs62559044), which coincides with a putative NF-κβ binding site [IFNG+874 (rs62559044) polymorphism was observed [IFNG CA14) were associated with CM in P. falciparum-infected children, and IFNG −183G/T (no rs designation available) and IFNG(CA)14/(CA)14 genotypes were more frequent in children with uncomplicated malaria than in children with cerebral malaria from Mali [Type 1 helper T lymphocytes may be protective through the release of IFN-ic cycle . Howeverseverity , 130. Stin vitro , and it ing site . In Gambobserved . Howeverrom Mali . IL-13, an SNP −1055T>C (rs1800925) has showed a significant association with protection from severe malaria in Thailand [IL-13 gene using the same malaria subjects revealed that only rs1881457 located in the promoter region, which is in linkage disequilibrium with rs1800925, showed a significant association with severe malaria [IL-13 gene were found to be significantly different between those who have experienced one or more malaria attacks within past 10 years and those who did not in Sri Lanka [Concerning Thailand . A fine  malaria . Furtherri Lanka .Plasmodium parasites. Low levels of IL-12 have been associated with the pathogenesis of malaria in children and nonimmune adults through the promotion of IFN-γ release from cells of the innate immune system, while high levels of this cytokine are associated with severe malaria [IL12A gene (chromosome 3p12-q13.2) and a 40-kD subunit encoded by the IL12B gene (chromosome 5q31–33), which exerts its effects on the immune response through receptors encoded by IL12RB1 and IL12RB2 [IL12B, IL12B-pro (rs17860508) has been associated with susceptibility to cerebral malaria [IL12A (rs2243140) and IL12RB1 (rs429774) confer protection against severe malarial anemia [IL-12 is a proinflammatory cytokine that boosts erythropoietic responses in infections with  malaria . IL-12 c IL12RB2 . A mutat malaria , 140. Th malaria . Moreovel anemia .IL-4 gene have been described, and four polymorphisms were described in the promoter region in association with total IgE production [IL-4 −589C>T (rs2243250) influence on IgE levels, there was no association with severe malaria [IL4 gene on predisposition to malaria in Mali found a genetic association between IL4 VNTR (rs8179190) and others IL4 mutations  with severe disease, supporting the view that IL4 genetic alterations could be a risk factor for malaria severity [IL-4 is a pleiotropic cytokine with multiple immune-modulating functions in several cells . IL-4 ploduction –146. Des malaria , 147. Hoseverity .Plasmodium infection [IL1A and IL1B) encode IL-1, which are located in chromosomal region 2q14, an area that also contains genes for IL-1 receptor types 1 and 2 (ILR1 and IL1R2), the IL-1 receptor antagonist (IL1RN), and other homologous genes that have not been well characterized [β might help control invading malaria parasites through the induction of an acute inflammatory response as part of the first line of defense; however, the overproduction of IL-1β might cause severe pathogenic effects [IL1B gene  have been associated with IL-1β plasma levels [IL1B −511A allele was associated with an increased risk of severe malarial anemia and reduced levels of IL-1β [IL1A +4845G>T (rs17561) and IL1B +3954C>T (rs1143634) were associated with symptomatic malaria [IL-1 is an endogenous pyrogen that plays an important role in the innate immune response of the human host to nfection . Two difcterized . The rap effects . Three da levels . The IL1of IL-1β . In anot malaria .IL-10 gene is located on chromosome 1q31-32 within the promoter region and includes the well-defined SNPs IL-10 −1082A>G (rs1800870), IL-10 −819T>C (rs1800871), and IL-10 −592A>C (rs1800872) [α, and IL-12 [IL-10 gene and malaria severity [IL-10 is an anti-inflammatory Th2-type cytokine produced primarily by monocytes and lymphocytes, and IL-10 exhibits various effects in the regulation of the immune response, including downregulating the expression of the proinflammatory (type 1) immune response . The IL-1800872) . The SNPnd IL-12 . Howeverseverity . A studyseverity .Plasmodium. Thus, polymorphisms in the immune response might influence host disease tolerance against malaria.Several SNPs influence the levels of pro- and anti-inflammatory cytokines in malaria infection and might lead to an imbalance between these molecules that favor increased host susceptibility to γRIIAFc gene contains an important SNP with a G>A substitution in the region responsible for encoding the ligand-binding domain in which histidine (H) replaces arginine (R) at position 131 in the extracellular domain (no rs designation available). Both allotypes bind to human IgG1 and IgG3, but the γRIIA H131Fc allotype exhibits higher binding affinity to the IgG2 and IgG3 than the γRIIA R131Fc allotype, but none effectively binds to IgG4 [γRIIA H131Fc allotype is the only FcγR that binds with high affinity to IgG2, and this allele is essential for the phagocytosis of microorganisms opsonized with IgG2 and the clearance of immune complexes containing IgG2 [γRII [RR131 genotype protects against high levels of parasitemia, whereas the HH131 genotype was associated with susceptibility to severe malaria with high parasite burden [FcgRIIA-RR131 genotype and severe malaria [Receptors for the Fc fragment of IgG (FcyRs) provide an important link between humoral and cellular immune responses. There are three families of FcyR . The primary function of FcgRs is the activation of accessory cells against pathogens; thus, FcgRs are essential molecules in the host defense against infection . Among t to IgG4 . The Fcγing IgG2 , 161. FuG2 [γRII . The RR1e burden , 164. An malaria . Plasmodium reflects parasite killing through reactive nitrogen metabolites and a decrease of endothelial adhesion molecules [NOS2 gene have been associated with malaria severity. In Gambia, the SNP NOS2 −954G> C (no rs designation available) has been associated with resistance to severe malaria [NOS2 transcription start site were associated with fatal malaria [NOS2 −954G>C polymorphisms nor CCTTT repeats were associated with severe malaria [NOS2, −1173C>T (no rs designation available), was associated with protection against cerebral malaria in children in Tanzania and severe anemia in malaria individuals of Kenya [NOS2 polymorphisms and susceptibility to malaria was described [NO is a highly diffusible, lipid soluble-free radical that mediates the resistance of host severe malaria and other diseases. The production of NO and the cellular expression of enzyme-inducible nitric oxide synthase (NOS2) are associated with protection against severe forms of malaria . The proolecules , 168. Inolecules . Several malaria , whereas malaria . However malaria . Anotherof Kenya . Howeverescribed . The FcgR receptor and NO are important molecules involved in malaria outcomes, and several studies have attempted to associate mutations in these genes with increased susceptibility to develop severe forms of malaria. However, the results are conflicting, and no conclusion has yet been determined.P. falciparum-mediated malaria is the adhesion of infected erythrocytes to capillary endothelium [P. falciparum is its ability to form rosettes, a property in which parasitized erythrocytes bind uninfected erythrocytes to form clumps of these cells [P. falciparum to erythrocyte membrane protein1 (PfEMP1), which is expressed on the membrane of an infected RBC among a variety of uninfected RBC receptors, such as serum components, blood group antigens A and B, glucosaminoglycans, and complement receptor 1 (CR1) [One of the peculiar characteristics of othelium . This asothelium , 175. Thothelium –178. Theothelium . Anotherse cells . The mecse cells –183. The 1 (CR1) .Plasmodium on brain vascular endothelial cells with the increased expression of adhesion molecules, particularly ICAM-1 [P. falciparum infection [ICAM-1 gene, ICAM-1 Killifi (rs5491), which results from substitution of lysine for methionine at position 56 of the coding sequence, and a less well-described polymorphism  [ICAM-1 Killifi polymorphism has been associated with both the resistance [Autopsy studies of patients with fatal cerebral malaria or severe malarial anemia showed the sequestration of erythrocytes infected with y ICAM-1 . The resy ICAM-1 . The ICAy ICAM-1 . ICAM-1 nfection , 189. Tw, K469E) . The ICAsistance , 191 andsistance . Howeversistance , 193–197P. falciparum antigens bind to the CD36 molecule, and thus CD36 is considered the most important endothelial receptor for the sequestration of infected erythrocytes [CD36 receptor gene have been associated with protection against or susceptibility to severe forms of malaria. The CD36 deficiency might be induced through the two SNPs in the CD36 gene , which encode the truncated proteins that were expressed at high frequency in patients with severe malaria in Gambian, Tanzanian, and Kenyan patients [CD36 gene in malaria patients from Thailand identified two SNPs in the promoter region  that were associated with protection against cerebral malaria and one microsatellite polymorphism in intron 3 with 12 TG repeats that has been associated with the lower risk of cerebral malaria [CD36 gene influence the malaria outcome, regardless of different conclusions concerning the polymorphisms identified in this molecule, perhaps reflecting differences among the populations and clinical spectrums of the disease.Most hrocytes . CD36 ishrocytes . CD36 sehrocytes . Mutatiopatients –201. Thipatients . A scree malaria . GeneticP. falciparum [PECAM-1 gene is polymorphic, and several polymorphisms have previously been described in the extracellular domain  and promoter region (GATA-2) [CD31 gene were associated with an increased risk for developing cerebral malaria in Thailand [PECAM-1 gene (exon 3 rs668 L/V) was identified as a risk factor for malaria in an endemic region, but this gene exhibited a significant association with protection from disease in a nonendemic region [CD31 gene might affect the regulation of inflammation because it is present within the first IgG-like domain of the PECAM-1 molecule, which has been associated with hemophilic adhesion and regulates leukocyte transmigration [Platelet-endothelial cell adhesion molecule 1 (PECAM-1/CD31) is expressed in hematopoietic and endothelial cells. This adhesion molecule was identified as an endothelial receptor for erythrocytes infected with lciparum . The PEC(GATA-2) . HomozygThailand . HoweverThailand . Furtherc region . The mutigration , 208. ThCR1 gene. Homozygous subjects for the 7.4 kb HindIII genomic fragment  have high levels of CR1 on erythrocytes, whereas homozygous individuals for the 6.9-kb genomic HindIII fragment  exhibit low expression, and HL heterozygous individuals show intermediary levels of CR1 in the membrane of erythrocytes [L allele and protection from severe malaria was not observed [LL genotype was demonstrated as a risk factor for severe malaria [L allele (HL) were correlated with protection against severe malaria [CR1 gene (rs9429942) was associated with higher levels of CR1 on the surface of RBC and protection against cerebral malaria in Thailand [CR1 genotype with malaria might be associated with the endemicity of malaria in different regions and an under or overestimation of the actual CR1 levels and interactions between CR1 and other genetic alterations [Complement receptor type 1 (CR1/CD35) is a membrane glycoprotein expressed in various cells, including erythrocytes, monocytes, B and T cells, monocytes, and dendritic cells . CR1 binhrocytes . The assobserved , 215. In malaria , and in  malaria . A new pThailand . Differeerations .Over the past several years, an increase in the number of scientific publications associated with the genetic predisposition to malaria and severe forms of this disease has been observed. As a result of technological advances, studies of SNPs were exchanged for studies with sophisticated gene sequencing and analyses using advanced molecular biology software. On the basis of the discovery of new functional mutations that alter the expression of several proteins fundamentally implicated in malaria pathogenesis, it is possible to individualize patient care depending on host genotype, as previously demonstrated . HoweverThe clinical manifestation of malaria is primarily described by the lysis of infected erythrocytes and subsequent immune and inflammatory response. Thus, it is critical to understand the role of genetic alterations in this pathway that might influence the disease outcome and severity of malaria. Furthermore, it should be observed that not merely one genetic alteration but rather the combination of a set of genetic factors might influence the susceptibility or resistance to malaria . The res


Plasmodium falciparum from four semi-urban villages near Ile-Ife, Osun State, Nigeria.Malaria is a major cause of morbidity and mortality worldwide with over one million deaths annually, particularly in children under five years. This study was the first to examine plasma cytokines, chemokines and cellular immune responses in pre-school Nigerian children infected with P. falciparum density per μl of blood (uninfected (n = 89), low density , medium density  and high density ). IL-12p70, IL-10, Nitric oxide, IFN-γ, TNF, IL-17, IL-4 and TGF-β, C-C chemokine RANTES, MMP-8 and TIMP-1 were measured in plasma. Peripheral blood mononuclear cells were obtained and examined markers of innate immune cells . T-cell sub-populations  were intracellularly stained for IL-10, IFN-γ and TNF following polyclonal stimulation or stimulated with malaria parasites. Ascaris lumbricoides was endemic in these villages and all data were analysed taking into account the potential impact of bystander helminth infection. All data were analysed using SPSS 15 for windows and in all tests, p <0.05 was deemed significant.Blood was obtained from 231 children (aged 39–73 months) who were classified according to mean P. falciparum parasitaemia was positively associated with plasma IL-10 and negatively associated with IL-12p70. The percentage of monocytes was significantly decreased in malaria-infected individuals while malaria parasitaemia was positively associated with increasing percentages of CD54+, CD11c+ and CD56+ cell populations. No association was observed in cytokine expression in mitogen-activated T-cell populations between groups and no malaria specific immune responses were detected. Although A. lumbricoides is endemic in these villages, an analysis of the data showed no impact of this helminth infection on P. falciparum parasitaemia or on immune responses associated with P. falciparum infection.The level of P. falciparum exhibit immune responses associated with active malaria infection and these responses were positively associated with increased P. falciparum parasitaemia.These findings indicate that Nigerian children infected with  Plasmodium falciparum malaria accounts for approximately 250–300 billion clinical cases of malaria worldwide and is highly endemic in Africa [P. falciparum infection [P. falciparum infection.n Africa . ApproxiP. falciparum infection [P. falciparum infection [Malaria infection is predominantly characterized by a T helper 1 (Th1) response and the production of pro-inflammatory cytokines such as IL-12-p70, interferon gamma (IFN-γ) and tumour necrosis factor (TNF). These inflammatory cytokines are considered critical in controlling parasitaemia, especially during the early stages of nfection ,4. Convenfection ,6. Regulnfection ,6. Therenfection .Malaria infection is strongly influenced by the release of inflammatory mediators from innate immune cells where early interactions between blood-stage parasites and these are critical in controlling parasitaemia and the subsequent elimination of infection ,6. InnatPlasmodium falciparum infection is endemic in this region with a high prevalence in pre-school children [Ascaris lumbricoides in this cohort [A. lumbricoides upon P. faliciparum parasitaemia and its associated immune responses were examined.This is the first study to assess immune responses during uncomplicated malaria infection in Nigerian pre-school children in four semi-urban villages near Ile-Ife, Osun State, Nigeria . Plasmodchildren . Recent s cohort . Since hs cohort -15 the pP. falciparum infection and examine the impact of A. lumbricoides. Data were available on children’s age and infection status for P. falciparum and A. lumbricoides infection. Children who suffered from severe malaria were treated and excluded from the study and therefore only individuals with uncomplicated malaria were included  [231 blood samples were obtained from children at the final time point in a double-blind placebo-controlled randomized trial on children aged 39–73 months in four semi-urban villages, Akinlalu, Ipetumodu, Moro and Edunabon, near Ile-Ife, Osun State, Nigeria. Details of the study area, design and participants were published previously . This cu>37.5°C) . The stuTen ml of blood (in tubes containing heparin) was obtained from 231 children, ranging in age from 39–73 months. Peripheral blood mononuclear cells (PBMCs) and plasma were obtained following histopaque  density gradient centrifugation. PBMCs were collected and stored in liquid nitrogen and plasma samples were stored at −80°C.Human IFN-γ, IL-10, TGF-β, TNF, IL-4 and IL-12p70 Opti-EIA kits (BD Biosciences) and human IL-17, RANTES, MMP-8 and TIMP-1 DuoSet ELISA Developmental Kits  were used to quantify cytokine, chemokine and metalloproteinase levels in plasma samples as described per manufacturers instructions. NO levels were also measured in plasma using the Greiss Reagent System .The following mAbs were used for cells surface staining and intracellular cytokine staining: FITC-conjugated anti- CD4, CD14, CD36, CD56, IFN-γ; PE-conjugated anti- γδTCR, CD54, IL-10; and APC-conjugated anti- CD3, CD11c, HLA-DR, IL-2 and TNF . Isotype controls included FITC-conjugated mouse IgG1, IgM, IgG2a, IgG2b; PE-conjugated mouse IgG1, IgG2b and APC-conjugated mouse IgG1, IgG2b and rat IgG2a (eBiosciences). PBMCs were thawed and cultured in complete RPMI containing 10% FCS , 1% L-glutamine and 1% penicillin/streptomycin solution . For intracellular cytokine staining, PBMCs were stimulated with 50 ng/ml PMA (Phorbol 12-myristate 13-acetate) and 1 mg/ml ionomycin for 4 h and to block cytokine secretion, 10 mg/ml Brefeldin A (Sigma) was added to the culture media. Cells were then washed and stained with cell surface mAbs, fixed with 4% PFA and permeabilized with 0.2% saponin (Sigma), before incubation with antibodies for IL-12, IFN-γ, IL-10 and TNF cytokines. Appropriately labelled isotype-matched antibodies were used as controls. Acquisition was performed using a FACSCalibur flow cytometer (BD Biosciences), and analysis of results performed using FlowJo software (Tree Star). A sample of gating strategy for T Cells in shown in Additional file 6 cells/ml) from a cohort of children were also cultured on a 24-well plate with mycoplasma free P. falciparum parasites (at a ratio of 1:5), which were extracted from cell culture by saponin lysis (0.15%), were kindly provided by Dr Alison Creasey, University of Edinburgh, Scotland. After three days, cell culture supernatants were harvested and frozen for subsequent measurement of IFN-γ, IL-10, and IL-5 by commercial ELISA.PBMCs , low density , medium density  and high density ) to determine if an association exists between parasitaemia and plasma immune factors  [+ monocytes (precursor dendritic cells (DCs)/macrophage) in PBMCs for each group were examined. All groups displayed significantly lower percentages of CD14+ cells (<4%) compared to endemic controls (5-7%) . To dissect the APC subsets associated with malaria infection specific surface markers including HLA-DR (indicative of an active infection), CD11c (myeloid marker found on DCs), CD54   and CD36  were examined [+ populations were associated with high density P. falciparum parasitaemia only  while the percentage of CD11c+ populations were associated with medium (P ≤0.01) and high (P ≤0.01) but not low density P. falciparum parasitaemia  . Here, texamined -21. The y Figure ; P ≤0.01a Figure . No asso+ Figure  and CD36s Figure  and paraP. falciparum parasitaemia and studies have shown that in the early stages of infection CD56+ natural killer cells (NK) and other leukocytes expressing the CD56 marker are good sources of IFN-γ [+ cells in PBMCs were measured and these cells were positively associated with P. falciparum parasitaemia with significant increases in cell percentages for medium (P ≤0.05) and high density P. falciparum parasitaemia (P ≤0.05)  Figure .PBMCs were polyclonally activated with PMA and ionomycin and intracellular cytokine staining for IFN-γ, IL-10, IL-2 and TNF was performed. In order to evaluate the phenotype of the T cells present, cells were also stained for CD3, CD4, and γδ T-cells. All groups expressed significantly high levels of IFN-γ and TNF and low, but significant, levels of IL-10 and IL-2 following stimulation. There were no differences observed between the groups  from malaria infected (n=23) and non-infected (n=7) individuals were stimulated with mycoplasma free P. falciparum parasites (at a ratio of 1:5) and after three days IFN-γ, IL-10, and IL-5 were measured in supernatant. No parasite specific immune responses were detected while cPBMCs were capable of secreting all cytokines tested in response to our positive control PMA/anti-CD3 , Ascaris only (n=21), malaria only (n=109), Ascaris and malaria (n=32)). The prevalence of A. lumbricoides was 23% and all A. lumbricoides-infected children had a low intensity infection ). Plasmodium falciparum percentages in the blood were calculated in the malaria-infected and co-infected individuals and no differences in P. falciparum parasitaemia were observed between the malaria-infected and co-infected groups . The pfected n=9, AscariThis study provides valuable insights into the immune responses associated with malaria infection in pre-school Nigerian children from 39–73 months. Studies looking at the immunological parameters in this age group are important given that the highest malaria mortality rates occur in children under five years . StudiesP. falciparum parasitaemia and IL-10. IL-10 is a known antagonist of this pro-inflammatory cytokine [P. falciparum parasites did no exhibit antigen specific immune responses. Previous studies have reported that T-cell responses can be weak in young children infected with malaria and this lack of responses could explain why this age group is most susceptibility to infection [Significantly high levels of IL-10 in plasma was observed from malaria-infected children and this corresponded with a reciprocal decrease in IL-12p70 levels, similar to that reported in other studies . Regresscytokine  and recucytokine . Intrace+ and CD54+ DCs in the infected individuals. The presence of predominantly mature CD11c+ DCs population may explain the lack of T-cell responses observed in young children as mature CD11c+ DC population lose its ability to phagocytose antigens which is necessary for presentation to effector and memory T-cells [+ cells supports previous findings which demonstrated a link between increased CD54 expression and disease severity [P. falciparum erythrocyte membrane protein 1 [The significant reduction in monocyte percentages in the infected groups compared to endemic controls was observed. Other reports have also shown a decrease in monocytes percentages during active parasitic infection . During  T-cells ,18. The severity . CD54 warotein 1 . CD11c a+ and this surface maker increased in the malaria-infected children. NK cells and γδT cells are thought to be critical in protection from malaria infection [Both γδ T cells and NK cell express CD56nfection ,30. Deplnfection . While tnfection ,32. WhilA. lumbricoides, no differences in immune parameters were observed between the co-infected groups compared to the P. falciparum-infected group only. Perhaps no differences were observed because children had a low intensity A. lumbricoides infection, as was demonstrated in a previous report study by Nacher et al. (2000). Moreover, since infection resides in the gut, perhaps only the medium and high intensity infection can alter the immune response systemically. Ascaris lumbricoides infection can be protective in the more severe forms of P. falciparum infection [While the study region is endemic for nfection  and sincP. falciparum parasitaemia. Increases in innate immune cell populations that were previously associated with disease severity in malaria-infected individuals was also demonstrated [This data corroborates previous reports examining immune responses in malaria-infected children by showing that increases in IL-10 were positively associated with increased nstrated ,21,33. Gnstrated , and valnstrated .GlaxoSmithKline sponsored the drug albendazole, which was used in larger clinical trial. The authors declare that they have no competing interests. The authors also declare that they have no financial competing interests.CN carried out all immunological experiments and drafted the manuscript. MP is our biostatistician and performed the statistical analysis. DJD provided assistance in the immunological assays, AA provided assistance in the immunological assays, PK collected clinical samples and provided the parasitological data, SFM collected clinical samples, SOA participated in the design of the study, CH conceived the study, and participated in its design and coordination. SMO’N conceived the immunological aspects of study, participated in its design and edited the manuscript. All authors read and approved the final manuscript.Sample of gating strategy for T Cells. Shown is a PBMC sample stimulated with 50 ng/ml PMA and 1 mg/ml ionomycin for 4 h in the presence of BFA (10 mg/ml). Cell subsets were identified as CD3 cells and then analysed for expression of cytokines and markers γδcells. Click here for fileAscaris only, malaria only, Ascaris and malaria.The average age, parasitemia, cytokine, nitric oxide (NO), RANTES, metalloproteinase (MMP) type 8 and tissue inhibitor of metalloproteinase (TIMP) type 1 plasma concentrations from the study cohort classified according in infection status , RANTES, metalloproteinase (MMP) type 8 and tissue inhibitor of metalloproteinase (TIMP) type 1 plasma concentrations from the study cohort classified according to Click here for file


The first symptoms of malaria, common to all the different malaria species, are nonspecific and mimic a flu-like syndrome. Although fever represents the cardinal feature, clinical findings in malaria are extremely diverse and may range in severity from mild headache to serious complications leading to death, particularly in falciparum malaria. As the progression to these complications can be rapid, any malaria patient must be assessed and treated rapidly, and frequent observations are needed to look for early signs of systemic complications.Plasmodium falciparum malaria is the major cause of severe malaria and death, increasing evidence has recently emerged that Plasmodium vivax and Plasmodium knowlesi can also be severe and even fatal.In fact, severe malaria is a life threatening but treatable disease. The protean and nonspecific clinical findings occurring in malaria  may lead physicians who see malaria infrequently to a wrong diagnosis, such as influenza , dengue, gastroenteritis, typhoid fever, viral hepatitis, encephalitis. Physicians should be aware that malaria is not a clinical diagnosis but must be diagnosed, or excluded, by performing microscopic examination of blood films. Prompt diagnosis and appropriate treatment are then crucial to prevent morbidity and fatal outcomes. Although  Malaria is usually transmitted by the bite of an infected female anopheline mosquito, although blood-borne transmission  or congenital transmission may occur.1Plasmodium falciparum) and 15 days . In case of Plasmodium vivax and Plasmodium ovale infections, a proportion of parasites may remain dormant in hepatocytes as hypnozoites for several months up to 5 years. From the clinical point of view, the hepatic schizogony is asymptomatic, as only a few number of liver cells is infected.2In the case of mosquito-borne transmission, sporozoites, the infective plasmodial stage injected along with saliva into subcutaneous capillaries, disappear from the blood within approximately 45 minutes of the bite and enter liver parenchimal cells (hepatocytes). Inside the hepatocytes, each sporozoite begins a phase of asexual reproduction resulting in the formation of a schizont, which contains thousands of merozoites. The rupture of mature schizonts generates the liberation of merozoites into the bloodstream. The hepatic phase of parasite development (hepatic schizogony) lasts on average between 5.5 . Within the red blood cell, merozoites mature to trophozoites and schizonts, which then rupture liberating the new generation of merozoites to invade other red blood cells and thus continue the erythrocytic cycle.At the time of schizont rupture, the release of malaria parasites and erythrocytic material into the circulation induce the pathophysiology process of malaria and the onset of symptoms.The activation of the cytokine cascade is responsible of many of the symptoms and signs of malaria.P. falciparum infections, tending to present the shortest, and P. malariae the more prolonged times. In most of P. falciparum and P. vivax malaria, the incubation period is approximately two weeks. In blood-induced infections, the incubation period is usually shorter with symptoms developing within 10 days of transfusion for P. falciparum, 16 days for P. vivax, and 40 days or longer for P. malariae.P. falciparum have been described as long as 2,P. falciparum in immigrants.6While the interval from time of infection until parasites become detectable in the blood is termed prepatent period, with the term of incubation period is defined the interval between infection and the onset of symptoms. The duration of incubation period is influenced by several factors such as the species of infecting parasites, the way of parasite transmission, the degree of previous immune status of the host, the chemoprophylactic use of antimalarial drugs, and probably the density of parasite inocula. Incubation period ranges from 9 to 30 days with Prolonged incubation period may also be caused by the use of antimalarial drugs that, although ineffective, may impact on the parasite multiplication rate.P. falciparum malaria is stable, severe malaria most commonly occurs in children up to 5 years of age, while is less common in older children and adults because of the acquisition of partial immunity. In areas of lower endemicity, the age distribution of severe malaria is less well defined and may also occur in adult semi-immune persons.The clinical manifestations of malaria are dependent on the previous immune status of the host.The first symptoms of malaria, common to all the different malaria species, are nonspecific and mimic a flu-like syndrome. The hallmark of malaria is fever. Up to two days before the onset of fever, prodromal symptoms, such as malaise, anorexia, lassitude, dizziness, with a desire to stretch limbs and yawn, headache, backache in the lumbar and sacroiliac region, myalgias, nausea, vomiting and a sense of chillness may be experienced.P. vivax and P. ovale infection, if left untreated, asexual cycles become synchronous after 5 to 7 days causing periodic febrile paroxysms. The classical malaria paroxysm presents three stages: a cold stage, followed by a hot stage with a terminal sweating stage. The cold stage is typically characterized by a sudden onset with a feeling of extreme coldness. The subject may shiver and his or her teeth may chatter. In virtue of an intense peripheral vasoconstriction phenomenon, the skin is cold, dry, pale, cyanosed and sometimes goose-pimpled.In At the physical examination, splenomegaly may be present during the acute attack but is more commonly observed after the second week of the attack. Rupture of an enlarged spleen is a possible, although rare, complication. The liver may also be enlarged and palpable.As far as laboratory findings are concerned, some degree of anaemia and reticulocytosis may be present due to lisys of parasitized and unparasitized red blood cells. Thrombocytopenia is common and sometimes mild leucopenia is present. By examining blood films, representatives of all developmental forms of the asexual parasite, from the early ring to mature schizont, may be observed, while gametocytes are usually present after a period of about a week. The density of parasitemia seldom exceeds 2% of the erythrocytes.P. vivax and P. ovale infection, schizogony occurs every 48 hours so that the febrile paroxysm occurs every third day (tertian fever). During the intervals between febrile paroxysm, the subject is usually afebrile and feels well. If left untreated, the attacks may last from a few weeks to some months and then spontaneously and gradually resolve. In P. vivax and P. ovale infection, after a quiescent or latent period, relapse may occur with renewal of clinical symptoms and asexual parasitemia. This phenomenon is due to reinvasion of the blood by merozoites produced when hypnozoites awake from dormancy and develop into hepatic schizont. Relapses occur weeks, months, or even years after the primary infection with different timing related to the P. vivax strain, geographical origin of the infection and the previous use of inadequate antimalarial treatment. From the clinical point of view, relapse is similar to the first attack, except for a more abrupt onset and the absence of the initial period of irregular fever, as the infection is more synchronous. The relapse is usually less severe and of shorter duration than the first attack.In P. vivax and P. ovale are rarely complicated. However, there is increasing evidence of serious and fatal complications due to P. vivax infection.12Infections with P. falciparum malaria, the onset of fever occurs after few days of prodromal symptoms started during the last days of the incubation period . At first, fever is irregular, but usually occurs daily. It may be intermittent or continuous, and shows no sign of periodicity until the illness has continued for a week or more. The symptoms present in the prodromal phase continue and increase, so configuring a flu-like syndrome. Anorexia, dispepsia, epigastric discomfort, nausea, vomiting and watery diarrhoea are frequent and may be misdiagnosed as a gastrointestinal infection. Herpes labialis may be present. A dry cough and an increase in the respiration rate may be observed, arising the suspect of an acute respiratory infection. Other non-specific physical findings are tender hepatosplenomegaly, orthostatic hypotension, and some degree of jaundice. The pulse may be rapid (100 to 120 beats/min) and the blood pressure may be low .In Routine laboratory exams may show little or no anaemia in mild cases and in otherwise healthy individuals. When present, it is usually normochromic and normocytic. The reticulocyte count is normal or depressed despite haemolysis, and increases only after the parasitemia is cleared. Serum haptoglobin may be undetectable indicating haemolysis. However, the degree of anaemia may greatly vary and is not always an indication of the severity of the attack.The white cell count is usually normal, but leucopenia with a count of 3,000–6000 cells/μl may be observed. Thrombocytopenia is common  and does not correlate with severity. Serum transaminases and lactic dehydrogenase usually are moderately elevated as well as bilirubin concentrations, both conjugated (hepatocyte disfunction and/or cholestasis) and unconjugated (haemolysis). Prothrombin and partial tromboplastin time may be prolonged while fibrinogen levels are usually elevated. C-reactive protein and procalcitonin value are usually increased in both uncomplicated and severe malaria with levels correlated with parasitemia and prognosis according with some studies.Examination of peripheral blood film mostly reveals the presence of early trophozoites , often numerous, with multiple infected red blood cells. Late trophozoites, as well as schizonts, are seldom observed, being their presence an indicator of very heavy infections and poor prognosis. Gametocytaemia usually occurs in the second week after the onset of parasitemia and may persist for some weeks after cure.1P. falciparum malaria may progress very rapidly to severe malaria unless appropriate treatment is started. If the acute attack is rapidly diagnosed and adequately treated, the prognosis of falciparum malaria is good, even if complications may still occur. The response to treatment is usually rapid with resolution of fever and most symptoms within 3 days.Although the subject may not appear very ill, serious complications may develop at any stage. In non-immune people P. malariae causes the mildest and most persistent form of malaria infection.P. malariae infection are rarely observed. However, recrudescences may occur, more frequently during the first year and then at longer intervals, even after 30–50 years. P. malariae has no hypnozoite form, so recrudescences arise from persisting blood stage. Asymptomatic P. malariae parasitemia in blood donors may cause transfusion malaria.As far as laboratory findings are concerned, anaemia is less pronounced and leucopenia may be observed. Parasitemia rarely exceeds 1% of erythrocytes. Representatives of all developmental forms of the asexual parasite are usually present. Left untreated, the acute attack is self limiting but may last for several months before spontaneous remission occurs.P. malariae infection is associated with development of a nephrotic syndrome. First clinical manifestation often onsets before 15 years of age. Classically, edema and ascites are present and accompanied by laboratory evidence of heavy proteinuria, hypoalbuminemia and hyperlipidemia. P. malariae parasitemia is common in children, but not in adults. Transient clinical remissions with period of asymptomatic proteinuria are frequent but progressive deterioration and development of renal failure often occur within 3 to 5 years.13P. knowlesi is the species of plasmodium most recently identified as agent of human malaria.Macaca fascicularis) and pig-tailed (Macaca nemestrina) macaques.P. knowlesi malaria is the most common locally acquired human malaria in Malaysian Borneo ,P. knowlesi infection by using microscopy only is difficult because it is very similar to P. malariae.17Most of the severe malaria complications occur in non immune subjects with falciparum malaria and involve central nervous system , pulmonary system (respiratory failure), renal system  and/or hematopietic system (severe anaemia). As the progression to these complications can be rapid and severe malaria is a potentially fatal disease, any malaria patient must be assessed and treated rapidly, and frequent observations are needed to look for early signs of systemic complications.1P. falciparum asexual parasitaemia and no other obvious cause of symptoms, the presence of one or more of the clinical or laboratory features reported in Table 1, classifies the patient as suffering from severe malaria.7According to the most recent definition by World Health Organization (WHO), in a patient with P. falciparum malaria with cerebral manifestations, usually including coma . Malaria with coma persisting for > 30 minutes after a seizure is considered to be cerebral malaria.22In order to allow comparability of clinical and therapeutic findings, a strict definition of cerebral malaria was recommended.However, in clinical practice, subjects with any degree of altered consciousness and any other sign of cerebral dysfunction should be treated for severe malaria. Clinical evolution and neurologic findings are highly variable. Coma may onset suddenly or gradually, with initial drowsiness , confusion, disorientation, delirium or agitation.27If left untreated, cerebral malaria is probably nearly always fatal.36Respiratory failure may rapidly develop at any stage of an acute malaria but, in many cases, occurs when subjects are already recovering, parasitemia is cleared, and in comatose subjects, consciousness has been regained.While biochemical evidence of renal dysfunction is frequently observed in otherwise uncomplicated malaria, acute renal failure is another complication of falciparum malaria, much more common in adults than among children. Malaria acute renal failure may be defined as a urine output of <400 mL in 24 h in adults, or 12 mL/kg in 24 h in children, in spite of rehydration, and a serum creatinine of more than 265 μmol/l (>3.0 mg/dL). In practice for initial assessment, the serum creatinine alone is used.Jaundice is common in adult subjects with severe malaria, while relatively rare in children. It is generally mild or moderate, but in some cases may be marked. Among the jaundiced subjects, hyperbilirubinemia may be predominantly unconjugated, in case of extensive haemolysis of both parasitized and unparasitized erythrocytes, or conjugated, indicating hepatocytic disfunction. Apart from jaundice, signs of severe liver cell damage are uncommon. Concentrations of transaminases may be increased up to ten fold, but never to the level observed in viral hepatitis. The liver, as well as the spleen, is enlarged and tender, especially in young children and non immune adults.Severe malaria is associated with development of anaemia, usually normochromic and normocytic. However, in endemic areas the morphology may be influenced by the nutritional status of the subject and some helminthiasis, resulting in an associated microcytic (iron deficiency) and macrocytic (folic acid deficiency) component. The causative mechanisms are multifactorial, including haemolysis of infected and uninfected red blood cells, inappropriate bone marrow response, and numerous other individual factors .13Hypoglicemia has been detected in approximately 8% of adults and up to 30% of children with cerebral malaria.Blackwater fever is a syndrome presenting with passage of mahogany-coloured (or ‘Coca-Cola’-coloured) urine in association with severe intravascular haemolysis. The dark urine is due to haemoglobinuria.43Salmonella spp being the most common isolates .47Bacterial infection may arise in subjects with severe and uncomplicated malaria. Health care acquired infections such those associated with use of device (i.e. indwelling catheter or vascular line) or with the poor general condition of the patient  are possible.P. falciparum malaria is the major cause of severe malaria and death, increasing evidence has recently emerged that P. vivax can also be severe and even fatal.P. vivax infection have been reported, including complications of seizure, shock, jaundice, renal failure, severe anaemia,P. vivax infections as high or higher than those observed in P. falciparum malaria.P. ovale malaria is rarely severe. However, respiratory distress has also been reported as a rare complication of ovale malaria.P. knowlesi malaria is concerned, most cases are uncomplicated but complications are possible, and in a study conducted in Malaysia, approximately 1 in 10 patients developed potentially fatal complications, with a case fatality rate of 1.8%.Although Imported malaria is an increasing public health problem in many non endemic countries. Although some cases occur in migrants and refugees, returning travelers from tropical and subtropical areas represent the largest group of persons given a diagnosis of malaria.P. falciparum is responsible for nearly all of these deaths. The fatal outcome in malaria cases is attributable to different contributing factors, including failure to take or adhere to recommended prophylaxis, to promptly seek medical care in presence of symptoms, to promptly diagnose and initiate appropriate antimalarial treatment. The protean and nonspecific clinical findings occurring in malaria  may lead physicians who see malaria infrequently to a wrong diagnosis, such as influenza , dengue, gastroenteritis, typhoid fever, viral hepatitis, encephalitis. It is not uncommon that the correct diagnosis is performed at the emergency admission of a subject with fever and signs of cerebral involvement or other complications, having being visited a few days before by a physician who had prescribed antipyretic and antibiotic treatment.The high fatality rate is disturbing, ranging from 0.4% to 3% in Europe.P. falciparum malaria has been reported in immigrants.78Non immune pregnants in second and third trimester are at increased risk of developing life threatening malaria and are particularly susceptible to develop pulmonary oedema and hypoglycemia. Foetal death and premature labour are common.Other groups at increased risk for developping severe malaria are malnourished children, elderly and those with comorbidities.81In areas with intense transmission, repeated plasmodial infections may generate a long-term stimulation of the immune system and determine a syndrome named hyperreactive malaria splenomegaly (HMS). From the clinical point of view, most subjects present with a huge spleen (to the level of umbilicus or below), abdominal distension, and a dragging left-sided abdominal pain, sometimes so sharp to suggest perisplenitis or splenic infarction.P. falciparum, even if the initial blood film is negative or microscopy, or rapid diagnostic tests, are not available.In conclusion, although fever represents the cardinal feature, clinical findings in malaria are extremely diverse and may range in severity from mild headache to serious complications leading to death, particularly in falciparum malaria. Prompt diagnosis and appropriate treatment are then crucial to prevent morbidity and fatal outcomes. In fact, severe malaria is a life threatening but treatable disease. Physicians should be aware that malaria is not a clinical diagnosis but must be diagnosed, or excluded, by performing microscopic examination of blood films.


Plasmodium falciparum attacks.In tropical Africa, where malaria is highly endemic, low grade infections are asymptomatic and the diagnosis of clinical malaria is usually based on parasite density. Here we investigate how changes in malaria control and endemicity modify diagnostic criteria of P. falciparum prevalence in asymptomatic persons declined from 85% to 1% in children 0–3 years and from 34% to 2% in adults ≥50 years. Thresholds levels of parasitemia for attributing fever episodes to malaria decreased by steps in relation to control policies. Using baseline threshold during following periods underestimated P. falciparum attacks by 9.8–20.2% in children and 18.9–40.2% in adults. Considering all fever episodes associated with malaria parasites as clinical attacks overestimated P. falciparum attacks by 42.2–68.5% in children and 45.9–211.7% in adults.Parasitological and clinical data from the population of Dielmo, Senegal, monitored during 20 years, are analyzed in a random-effect logistic regression model to investigate the relationship between the level of parasitemia and risk of fever. Between 1990 and 2010, Malaria control modifies in all age-groups the threshold levels of parasitemia to be used for the assessment of malaria morbidity and to guide therapeutic decisions. Even under declining levels of malaria endemicity, the parasite density method must remain the reference method for distinguishing malaria from other causes of fever and assessing trends in the burden of malaria. In tropical Africa, where malaria is highly endemic, most individuals are semi-immune and asymptomatic malaria infections are highly prevalent. Thick blood films in children and adults are often positive regardless of the clinical context and the detection of malaria parasites in persons with fever is not sufficient criteria for distinguishing malaria from other causes of fever. Following early studies in the 1980s that have shown that parasitemia was much higher during malaria attacks than during asymptomatic chronic infections and that it was possible to use parasite density thresholds to confirm or to discard the diagnosis of clinical malaria with a low risk of error Plasmodium falciparum parasitemia which constitute the best threshold values for attributing to clinical malaria a fever episode in a given area and population Numerous studies have been conducted during the two past decades using various approaches and models to investigate the relationship between the dynamics of parasitemia and the occurrence of fever, and to determine levels of P. falciparum, all countries gradually abandoned chloroquine, either initially switching to sulfadoxine with pyrimethamine alone or the combination of amodiaquine plus sulfadoxine with pyrimethamine before switching to artemisin-based combination therapy (ACTs), or directly switching to ACTs. In addition, depending on the region, the change in first-line treatment of malaria attacks was preceded, followed, or accompanied by the mass distribution of insecticide-treated bednets Since the mid-2000s, there have been substantial changes in malaria and its control throughout tropical Africa. To face the dramatic consequences of the dissemination of high levels of resistance to chloroquine in P. falciparum malaria attacks based on parasite density measurement.Since 1990, the population of Dielmo, Senegal, has been involved in a long-term study of the host-vector-parasite relationships in malaria The study was carried out in Dielmo, a village situated in a Sudan-savannah region of central Senegal, on the marshy bank of a small permanent stream, where anopheline mosquitoes breed all year round P. falciparum.The study area, the procedures of medical, parasitological, entomological and epidemiological surveillance and the main characteristics of malaria in this village have been described previously Between June 1990 and December 2010, four first-line drugs regimens were successively used for antimalarial treatment: oral quinine (Quinimax®) (October 1990–December 1994), chloroquine (January 1995–October 2003), sulfadoxine/pyrimethamine+amodiaquine (SP+AQ) (November 2003–May 2006) and artesunate+amodiaquine (AS+AQ) (June 2006–December 2010). Antimalarials were systematically given to young children in case of fever associated with a parasite: leukocyte ratio ≥2 A total of 64,262 simultaneous measurements of parasitemia and temperature made from June 1990 to December 2010 among 760 individuals aged from two weeks to 99 years were included in the analysis. The following definitions of case and control observations were used.Individual observations were regarded as fever cases if the rectal temperature measured by active case detection at home or by passive case detection at the clinic was ≥38°C (young children) or the axillary temperature was ≥37.5°C (older children and adults). Two fever episodes were considered independent if they occurred fifteen days apart or more. When several simultaneous measurements of parasitemia and temperature were available for the same fever episode, only the highest measure of parasitemia and the temperature associated were taken into account. 14,819 observations of parasitemia and temperature matched the case definition.Owing to the erratic nature of hyperthermia during malaria attacks and a number of other diseases, individual observations from the cross sectional surveys were considered to be asymptomatic controls if rectal/axillary temperatures were lower than 38°/37.5°C and if there was no episode of illness  between fifteen days prior and seven days after the temperature was taken. Measurements from pregnant women were excluded from the analysis. 49,443 observations of parasitemia and temperature collected during cross-sectional surveys matched the control definition.P. falciparum clinical malaria attacks were defined as any case with fever or allegation of fever and/or fever-related symptoms  whose parasitemia was higher than the age and period corresponding pyrogenic threshold derived from the model below. Cases were counted separately if they occurred fifteen days apart or more.For incidence density calculation, The pyrogenic thresholds were investigated separately at the beginning of the study (baseline period) and during the five successive treatment periods: the oral quinine period (excluding June–September 1990), the chloroquine period, the SP+AQ period, the ACT period (June 2006–July 2008) and the ACT+LLIN period (August 2008–December 2010). Data from the baseline period are those collected during the first four months of the study, from June to September 1990 P. falciparum parasitemia. To take into account the interdependence of successive observations in the same individuals, a random-effect logistic regression model was used ij that the individual i presents a febrile episode during the observation j can be expressed in the form of a linear function of age zi and parasite density xij. Taking age into account, the best fit was obtained using a series of three dummy variables zik were k was an index coding for the four following age groups: 0–1, 2–6, 7–12, and ≥13 years old. Several different functions f(xij) of parasitemia were fitted into the model. As previously observed rth power of x was the best function (i.e. according to the best log likelihood fit) for the parasitemia to describe the fever risk as a continuous function of parasite density. The exponent r for the function f(xij) of parasitemia was tested at different values between 0.10 and 1.00 with a step of 0.05 for the first loop and then it was specified with a precision of 0.01. The existence of a threshold effect in addition to the previous continuous effect of parasitemia was demonstrated earlier ij. It took the value 0 when the jth parasitemia of the individual i was below the tested threshold level and the value 1 when it was higher. β0 was a constant, αi was the random-effects individual terms, β1, β2 and β3 were the regression coefficients:The individual risk of hyperthermia was analyzed as a logistic regression of age and The models for each study period were compared according to the maximum likelihood (minimum deviance) using the Akaike method a), the highest parasitemia (b), parasitemia at age 0 (c), the level of parasitemia in oldest adults corresponding to a plateau (d), and finally a parameter determining the shape of the decrease of the function (e). Equation h1 represent threshold values in infants and younger children before age a , and equation h2 represent threshold values in children and adults after age a.The pattern of the pyrogenic threshold was defined using five parameters: the age of maximal parasitemia in years  b and c were estimated with a precision of ±500 trophozoites/µl and parameter d with an additional precision of ±200 trophozoites/µl for values <1000 trophozoites/µl.Parameter All parasitemia estimates used in the models were derived from the parasite: leukocyte ratio that was measured when examining thick blood films. Since there was no simultaneous measurement of leukocytemia, when expressing the results in numbers of trophozoites per µl of blood, we adopted a mean standard leukocyte count of 8,000 per µl of blood for all age groups. This tends to underestimates the level of parasitemia in young children , and to overestimates parasitemia in adults  The project was initially approved by the Ministry of Health of Senegal and the assembled village population, and renewed on a yearly basis. Written informed consents were obtained individually from all participants or the parents of children younger than 15 years. For children participants aged 15–18 years, written informed consent were obtained individually since the National Ethics Committee of Senegal considered that participants in this age are responsible for their own person. Audits were regularly carried out by the National Ethics Committee of Senegal and ad-hoc committees of the Ministry of Health, the Pasteur Institute , and the Institut de Recherche pour le Développement .P. falciparum malaria prevalence and the mean level of parasitemia during asymptomatic infections decreased markedly from 1990 to 2010  and a second step when SP+AQ replaced chloroquine. In adults, prevalence decreased markedly after the additional introduction of LLINs in the last period. to 2010 . During P. falciparum malaria parasites and the mean level of parasitemia during these infections are shown in P. falciparum levels during fever episodes.For each period and age group, the proportion of individuals with fever harbouring Estimates with the lowest deviance of the parameters defining the shape and level by age of pyrogenic thresholds during the baseline and the five treatment periods are given in r, a, b, c and d very close or similar to those of the whole period. Similar results were also obtained when comparing data of the period December 2003–June 2004, i.e. the first six months of the SP+AQ period, with those of this whole period (data not shown).Since threshold levels decreased more markedly between the baseline period and the quinine period, then between the chloroquine and the SP+AQ periods, we investigated whether these decreases were progressive or occurred abruptly. When modelling data of the period October 1990–March 1991, i.e. the first six months of the quinine period, we obtained values of the parameters We compared three definitions of malaria attacks: (A) fever cases with parasitemia higher than the threshold measured for the corresponding treatment period; (B) fever cases with parasitemia higher than the baseline period threshold; and (C) all fever cases associated with the presence of malaria parasites, whatever the level of parasitemia. Because of the high prevalence of asymptomatic malaria infections and the non-specific signs and symptoms of the disease, the diagnosis of clinical malaria presents difficult methodological problems in malaria endemic areas, critical for first-line treatment decision and for accurate evaluation of any intervention aimed at malaria morbidity reduction. To estimate the fraction of fever cases that are attributable to malaria, several approaches corresponding to different definitions of malaria morbidity have been used in the literature, either for establishing national vital statistics or as part of specific studies. In most health facilities in Africa, there is no laboratory test for confirming or discarding the clinical diagnosis of malaria, and any fever case is presumed to be a malaria attack when specific signs of other diseases are lacking Since the mid-1980s, using various approaches , the parasite density method has become in Africa the gold standard to assess morbidity from malaria in community or out-patient studies, and to measure the efficacy of control strategies such insecticide-treated nets, drug prevention protocols, or malaria vaccine candidates To determine the level of the threshold of parasitemia for diagnosing malaria attacks, many studies have used the attributable fractions method, either to select threshold levels presenting the best compromise between sensitivity and specificity, or to select thresholds levels giving estimates of malaria incidence close of those directly calculated by the attributable fraction method. The concept of pyrogenic threshold is an old concept in malarialogy Data collected in Dielmo during 20 years show that even a limited use of antimalarials, strictly restricted to parasitologically confirmed malaria attacks, may have a major impact on asymptomatic parasite carriage. As expected, the decrease of parasitemia in asymptomatic individuals significantly decreased the threshold levels of parasitemia to be used for the assessment of malaria morbidity, with the lowest thresholds levels during the ACT+LLINs period. Interestingly, although using baseline threshold levels would underestimate the burden of malaria in all age-groups and in all treatment periods, differences between baseline period and period-specific based estimates of malaria morbidity only range between 11.7% and 22.1% at the community level, while the decrease of threshold levels was at least halved between baseline and the last periods. In fact, most malaria attacks in children are associated with peaks of parasite density much higher than the range of threshold levels derived from the models, and only a low proportion of asymptomatic parasitemia were close to this range. In adults, due to strong protective immunity, the duration of the peaks of parasitemia responsible for fever and other symptoms only last a few hours, and patients were seen in the dispensary at various stages of their clinical episode, often when parasitemia was probably yet decreasing Our study shows that malaria control modifies in all age-groups the threshold levels of parasitemia to be used for the assessment of malaria morbidity. Although treating with antimalarials any parasitologically confirmed infection may often be justified in order to prevent any risk related to misdiagnosis and/or to long-lasting parasite carriage in terms of morbidity and transmission, it appears that even under the low levels of malaria endemicity, where most young children are non-immune and acquired immunity in other age groups is declining, the parasite density method must remain in Africa the gold standard for distinguishing malaria from other causes of fever and assessing trends in the burden of malaria.


Malaria has a negative impact on health and social and economic life of residents of endemic countries. The ultimate goals of designing new treatment for malaria are to prevent clinical infection, reduce morbidity, and decrease mortality. There are great advances in the understanding of the parasite-host interaction through studies by various scientists. In some of these studies, attempts were made to evaluate the roles of malaria pigment or toxins in the pathogenesis of malaria. Hemozoin is a key metabolite associated with severe malaria anemia (SMA), immunosuppression, and cytokine dysfunction. Targeting of this pigment may be necessary in the design of new therapeutic products against malaria. In this review, the roles of hemozoin in the morbidity and mortality of malaria are highlighted as an essential target in the quest for effective control of clinical malaria. Plasmodium falciparum is responsible for most cases of malaria.Malaria has plagued humankind since ancient times and is still a significant threat to half of the world's population . Malariain vitro [The parasite's life cycle includes a cycle of asexual division in the human liver, another cycle of pigment-producing asexual division in red blood cells (RBCs), and a sporogenic development in the female anopheles mosquito. During the erythrocytic stage of development, the malaria parasite develops into a trophozoite form in a vacuole formed by the internal membrane of the host red cells. The trophozoite feeds on hemoglobin (Hb) by ingesting small amounts of red cell cytoplasm. The globin component is further digested into amino acids for the parasite's metabolic needs. However, heme is toxic to the parasite and is thus aggregated into the insoluble dark-brown crystal called hemozoin (Hz) which can accumulate in the parasitized red blood cell (pRBC). Both circulating and resident phagocytes acquire Hz through phagocytosis of pRBCs or free Hz crystals released after schizont rupture . The prein vitro . Furtherin vitro –16. The in vitro , immunosin vitro , 16, andin vitro –20. Thesin vitro –25. Thisin vitro , 22.Taken together, these findings suggest that Hz may be involved in both induction of immunity against malaria and the pathogenesis of the disease. In this brief review, we will evaluate reported roles of this pigment in the pathogenesis of malaria and provide the rationale for its targeting in antimalaria therapeutics development.Structural abnormalities and extensive deposition of Hz were observed in the livers and bone marrows of children with SMA –28. The P. falciparum malaria infection is usually responsible for severe morbidity and mortality in children and pregnant women in Sub-Saharan Africa. P. falciparum invades red cells of all ages [P. falciparum showed that the surface antigens could induce isolate-specific immunity [P. vivax isolates, it was observed that the intensity of rosetting was higher among anaemic individuals compared to non-anaemic and decreased with increasing haematocrit and haemoglobin levels [P. falciparum suggest that rosetting and cytoadhesion contribute to anaemia [P. falciparum was shown to be associated with SMA [Anemia from all ages  and digeall ages  into smaall ages . Free toall ages . The preall ages . Recogniimmunity . Parasitimmunity . In anotn levels . Consequ anaemia , 38. In with SMA .2O2, or haematin itself, the study concludes that the destabilising effect of haem products (haematin and beta-haematin) on red cell membrane may not result from oxidative damage of membrane lipids but from direct binding or incorporation to membrane. Furthermore, direct binding or incorporation of haem products to npRBC membrane is expected to initiate immunological responses and phagocytosis of npRBC.Trophozoites in the RBC grow and develop into schizonts which rupture the cell releasing merozoites and free Hz into blood circulation . CirculaAnother mechanism involves 4-hydroxynonenal (4-HNE). Rosetting is a specialized form of cytoadherence of late hemozoin-containing pRBCs to npRBCs . The aldα have been shown to inhibit all stages of erythropoiesis [α in both human and animal malaria infection [Hz has also been associated with direct inhibition of reticulocyte formation , 44. Preopoiesis , 47. Hz nfection –50.α and nitric oxide (see below).In all, Hz directly promotes SMA through enhancing increased hemolysis of RBC and inhibition of erythropoiesis. It also indirectly promotes SMA by triggering production of inflammatory cytokines such as TNF-α, interleukin IL-12, IL-10, macrophage inflammatory protein (MIP)-1α, MIP-1β, nitric oxide (NO), and prostaglandin (PG)-E2 [Previous investigations had shown that ingestion of Hz by monocytes may enhance malarial pathogenesis by causing dysregulation in the production of cytokine, chemokines, and effector molecules, including TNF- (PG)-E2 –20, 33.α [α [α is seen in acute P. falciparum malaria [α was reported in murine malaria [α was also reported in fatal compared to nonfatal cerebral malaria in African children [α was seen in cerebral malaria compared to uncomplicated malaria [α level was associated with abortions [Systemic symptoms of malaria like fever occur after the rupture of malaria schizont , 52 and α . In bothα [α –50, 53 aα [α , 55. Hig malaria  and is b malaria . However malaria , 58. Sim malaria , 60. Higchildren . Similar malaria . In addibortions , 64. Takα increases the expression of nitric oxide synthase 2 (NOS2) gene and generation of nitric oxide (NO). Initial high levels of NO appear to be protective against severe malaria [P. falciparum malaria anemia in children [Hz and pro-inflammatory cytokines including TNF- malaria , 66. Howchildren  by inhibchildren , 68.2 and COX-2 gene expression by PBMC are significantly reduced [2 inhibits TNF-α [2 synthesis such as Hz, acetaminophen, and salicylates are associated with high levels of TNF-α and increased malaria severity and mortality [2/TNF-α is associated with decreased Hb concentration [In children with acute malaria, plasma prostaglandin E reduced . This is reduced . PGE2 ints TNF-α  and appets TNF-α . Inhibitortality –75. In antration . Hz has ntration , 76 and ntration . IL-10 mntration , 78.α, NO and at the same time reducing the level of more beneficial IL-12 and prostaglandin E2. The role of anti-inflammatory cytokine IL-10 in malaria appears to enhance parasitemia since the Th1 immunological responses against the parasite are inhibited and IL-12 secretion is also suppressed by this cytokine. Taken together, Hz plays important role in deregulation of pro- and anti-inflammatory cytokines during malaria resulting in altered immunological responses to the disease, anemia, and host tissue damage.In summary, Hz appears to trigger pathological levels of pro-inflammatory cytokines and chemokines like TNF-Suppression of innate immune response during malaria infection has been reported in previous studies , 79. OneThe suppression of immunity during malaria infection may be responsible for associated clinical problems. For instance, studies have demonstrated increased viral load in HIV patients  as a resOn account of the global inhibition of innate and adaptive immune responses, Hz was described in previous studies as a potent immunosuppressant , 94. HowA number of harmful effects have been documented or associated with Hz. Hz compromises the functions of human monocytes, as previously noted, and this dysfunction has been related to its lipoperoxidation products, namely, 15-hydroxyeicosatetraenoic acid (15-HETE) and 4-HNE . Hz has One of the factors responsible for malaria pathogenesis is the suppression of host immune responses. This suppression enhances parasitemia and diminishes the host immune response to malaria-expressed proteins and other pathogens. Hz plays both direct and indirect roles in orchestrating this immunosuppression which may be important for the survival of the parasite and completion of its life cycle in the human host . BlockinUse of agents that will prevent formation of the pigment will prevent Hz-induced inhibition of erythroid precursors and also reduce the production of other mediators of SMA. Chloroquine, quinine, and artemisinin block the formation of Hz from heme , 22, 95.


Dengue and malaria are two major arthropod-borne infections in tropical areas, but dual infections were only described for the first time in 2005. Reports of these concomitant infections are scarce and there is no evidence of more severe clinical and biological pictures than single infections.To compare co-infections to dengue alone and malaria alone, a retrospective matched-pair study was conducted between 2004 and 2010 among patients admitted in the emergency department of Cayenne hospital, French Guiana.9/L, and low haematocrit <36% and independent factors significantly associated with co-infections versus malaria were red cells transfusion, low haematocrit < 36%, thrombocytopaenia < 50 109/L and low Plasmodium parasitic load < 0.001%.104 dengue and malaria co-infection cases were identified during the study period and 208 individuals were matched in two comparison groups: dengue alone and malaria alone. In bivariate analysis, co-infection clinical picture was more severe than separated infections, in particular using the severe malaria WHO criteria. In multivariate analysis, independent factors associated with co-infection versus dengue were: masculine gender, CRP level > 50 mg/L, thrombocytopaenia < 50 10In the present study, dengue and malaria co-infection clinical picture seems to be more severe than single infections in French Guiana, with a greater risk of deep thrombocytopaenia and anaemia. Flaviridae, genus Flavivirus) and Plasmodium parasites are widespread in American and Asian tropical regions and their endemic areas overlap extensively. Nevertheless, reports of malaria and dengue dual infection are scarce. Since the first case reported in 2005 [Plasmodium falciparum and/or Plasmodium vivax in India and Pakistan [Dengue fever and malaria are the most common arthropod-borne diseases in humans and represent major public health problems. Dengue virus . The screening sensitivity was ≈ 6 plasmodia/μL . The asexual parasite load (PL) was classified in five classes: class 5: >1.25%; class 4: 0.125 to 1.25%; class 3 : 0.0125% to 0.125%; class 2: 0.00125 to 0.0125%; and class 1: ≤0.00125. Malaria rapid diagnosis tests were not systematically performed on the study period. Due to the evolution of the techniques between 2004 and 2010, the laboratory diagnosis of dengue relied on different methods. Direct diagnosis was based on virus isolation, genome detection by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) or NS1 antigen detection introduced in 2006 in French Guiana. Indirect diagnosis was based on detection of specific anti-dengue IgM and/or IgA antibodies in patients’ sera . When NSrd and 5th day of fever but can persist for over three months and IgA appear concomitantly with IgM but does not persist longer than five to six weeks [Concerning dengue definition (groups MD and D), cases were separated in two groups: “confirmed acute dengue cases” (CADC) were defined by direct biological diagnosis (NS1 antigen and/or RT-PCR and/or virus isolation), IgM seroconversion  or IgA antibodies detection. “Likely dengue cases” (LDC) were defined by IgM antibodies detection. Indeed, IgM appear between the 3ix weeks ,19. TherPatients’ data, including socio-epidemiologic data, previous medical history, clinical symptoms, and biological results, were obtained from the computerized medical charts. Data were analysed using R version 2.10.0® and the Epicalc® package.The continuous variables of interest were categorized following the laboratory cut-off values, or published values. They generally were dichotomized because of the small sample size.odds ratio (OR) and the confidence intervals linked to co-infections.Two analyses were performed comparing separately MD to D and MD to M. For categorical variables, a matched bivariate analysis using the Wald test was performed to identify factors associated with co-infections. Statistical significance was set at p <0.05. Variables with a p-value < 0.2 in bivariate analyses were entered into multivariate model to identify the factors independently associated with dengue-malaria co-infections. As bivariate analysis were made in an exploratory way and used as a selection criterion for inclusion in the final multivariate model (p < 0.20), we did not judge as a necessity to adjust bivariate p-values for multiple comparisons. Thus, bivariate p-values near to 0.05 must be relativized. To obtain more powerful models, and because of the missing data inherent to retrospective studies, variables obtained from anamnesis and clinical examination and variables with more than 5% of missing data were excluded from the model. Thus, conditional multivariate backward stepwise logistic regression estimated the adjusted The retrospective use of anonymous patient files on the site of patient care is authorized by the French National Commission on Informatics and Liberties. All the data collected retrospectively were anonymized in a standardized case report form and in the database.p <0.001) in the group D, respectively (Table P. vivax between the MD group and M group: P. vivax (76.7% vs. 68.1% respectively), P. falciparum (20.4% vs. 28%) and association of P. vivax and P. falciparum (2.9% vs. 3.9%). Species identification was not possible in two patients because they had received anti-malarial treatment after positive rapid diagnostic testing in a health centre. A low PL (class 1 and 2) tended to be more frequent in the MD group than M group (p 0.08)  relative to dengue alone. Retro-orbital pain, skin rash and ENT symptoms were significantly associated with D. Anaemia (p 0.02), severe thrombocytopaenia (p <0.001), and elevated bilirubin (p <0.001) were more frequent in MD patients. CADC diagnoses were significantly more frequent in the D group than in the MD group. Anaemia, severe thrombocytopaenia, male gender, high CRP level and LDC diagnosis were significantly associated with co-infection in multivariate analysis ; RT-PCR: Reverse transcriptase-polymerase chain reaction (RT-PCR); SGOT: Serum glutamooxaloacetate transférase; SGPT: Serum glutamopyruvate transferase; WHO: World health organization.The authors declare no competing interests.LE participated in the design of the study, performed the statistical analysis, contributed to the analysis and interpretation of data and drafted the manuscript. MH performed the statistical analysis and contributed to the analysis and interpretation of data. PD carried out the the immunoassays and the RT-PCR, contributed to the analysis and interpretation of data and helped to draft the manuscript SOE contributed to conception of the study and the acquisition of data. FD conceived of the study and contributed to the analysis and interpretation of data and helped to draft the manuscript. MN conceived of the study and contributed to the analysis and interpretation of data and helped to draft the manuscript. BC conceived the study and contributed to the analysis and interpretation of data and helped to draft the manuscript. All authors read and approved the final manuscript.