Plasmodium, is a devastating disease with over 200 million new cases reported globally every year. Although immunization is arguably the best strategy to eliminate malaria, despite decades of research in this area we do not have an effective, clinically approved antimalarial vaccine. The current impetus in the field is to develop vaccines directed at the pre-erythrocytic developmental stages of Plasmodium, utilizing novel vaccination platforms. We here review the most promising pre-erythrocytic stage antimalarial vaccine candidates.Malaria, caused by the protozoan  Plasmodium. Plasmodium has a complex life cycle, with distinct, antigenically discrete developmental stages in both vertebrate and invertebrate hosts. According to the World Health Organization (WHO), in 2018 an estimated 228 million new cases of malaria were reported globally, most of which were distributed among just nineteen countries in sub-Saharan Africa and the Indian subcontinent [Plasmodium and are known to develop naturally acquired immunity with age that prevent them from being clinically symptomatic [Plasmodium parasites in the blood facilitating further transmission of the disease [Plasmodium species causing malaria in humans.Malaria is a mosquito-borne infectious disease caused by the eukaryotic pathogen, ptomatic , they ar disease ,5,6. HenPlasmodium sporozoites are delivered into the skin by the female Anopheles mosquitos during a blood meal. Subsequently, some of the motile sporozoites leave the bite site and travel through the blood-stream to find, invade and undergo development in the hepatocytes. The developmental progression of the Plasmodium parasites from the sporozoite stage inoculated in the skin to the completion of its development in the hepatocytes constitutes the asymptomatic, ‘pre-erythrocytic stage’ of malaria in its vertebrate host (Plasmodium development in the hepatocytes (liver-stage) is associated with significant changes in its gene expression and morphology. This process generates tens of thousands of merozoites that are released into the blood from the infected hepatocytes , which infect red blood cells and start the symptomatic and highly pathogenic blood-stage of malaria. Preventing the progression of the malaria parasites from the liver-stage to its blood-stage not only prevents the onset of clinical disease and morbidity but also stems transmission. Hence, the development of vaccines targeting the pre-erythrocytic stages of malaria has been a priority in the field for the past few decades.In humans, ate host . PlasmodPlasmodium parasites in the liver is limited through the coordination of innate and adaptive immune responses [Plasmodium-specific adaptive immune responses that prevent the progression of the infection. The TBVs, however, preclude transmission of malaria by generating neutralizing antibodies against the ookinete antigens in the hosts, which get taken up by the mosquitos along with the blood-meal [Plasmodium to the blood-stage by priming protective adaptive immune responses against the Plasmodium sporozoite- or merozoite-stage antigens [It is known that the replication of esponses ,8. Antimood-meal . PEVs haood-meal . These vantigens ,11. Plasmodium or the intricacies of its infection biology have all been major hurdles to our progress towards an effective vaccine against malaria. An ideal antimalarial vaccine would be safe and offer long-lasting Plasmodium-specific adaptive immune responses that are protective against the different Plasmodium species in humans. Other practical considerations like the potential for mass production, suitability of the administration route, vaccination schedule, dosage requirements, stability, shelf-life, cost-efficiency etc., are also important, given the target population for antimalarial vaccines live in the poorest parts of the world. Even though research over the years has made significant advances in the area of human malaria vaccines, we are yet to develop an antimalarial vaccine that is broadly protective and practical. We here review the most promising vaccination approaches targeting the pre-erythrocytic stage of malaria currently available or under development, along with the key studies that support them. Malaria, like other eukaryotic pathogen infections, presents major challenges when it comes to vaccinations. Our incomplete understanding of the basic immunology of malaria, a relative lack of knowledge of the genetic variability of Antigen subunit vaccines are designed to prime protective immune responses against a limited number of immunodominant epitopes in a pathogen. The following are the key subunit vaccination approaches pertinent to human malaria infection.Plasmodium in the mammalian host. While the sporozoite-specific antibodies generated in the immunized host preclude sporozoite invasion of the hepatocytes [Plasmodium-infected hepatocytes that present these epitopes [Although the underlying mechanisms behind eliciting immune responses to the pre-erythrocytic stages of malaria are not fully understood, it is known that protection from new infections can be induced by vaccines that generate strong humoral and cellular immune responses against the sporozoite stage of atocytes , sufficiepitopes . The Cirepitopes ,14,15. TMosquirix). The 58 kDa CSP protein contains 37–49 repeats of the NANP  amino acids and a smaller number of valine and aspartic acid residues [P. falciparum (NF54 strain) CSP central repeat region with the NANP amino acid repeat sequence (R) with a B-cell receptor epitope and immunodominant CD4 and CD8 T cell epitopes (T) fused to hepatitis B surface antigens . In addition to this, three times more ‘free’ HBsAg antigen (S) is made available in the vaccine formulation to facilitate the self-assembly of the immunogen into virus-like particles [Thus, it is not surprising that one of the most prominent antimalarial subunit vaccines is the CSP-based RTS, S/AS01 recombinant vaccine  as an adjuvant did not induce a robust immune response. None of the six volunteers developed protective immunity with alum alone while two out of eight volunteers were protected with alum-MPL ,25. Subsl trials . It was l trials . Howeverl trials . In phasl trials . Neverthl trials ,34. The l trials . Plasmodium, which typically invades the liver cells in under half an hour of being inoculated into humans [The RTS, S/AS01 vaccine, despite its clinical use, is far from being the ideal malaria vaccine. The protection offered is inadequate and wanes over time . The CSPo humans ,36. The o humans . In addio humans . Besideso humans ,38. The o humans ,40. Wheno humans ,42. The o humans . The advo humans ,45. PfCSP C-terminus bound to HBsAg N-terminus without the three-fold molar excess of HBsAg found in RTS, S/AS01 [Plasmodium sporozoite surface [PfCSP-transgenic P. berghei sporozoite challenge [R21 is considered the next generation antimalarial subunit vaccine, and is an improved version of the RTS, S/AS01 vaccine. The R21 design incorporates a higher proportion of , S/AS01 ,46. In t surface . This en surface . In BALBhallenge . A clinihallenge . R21 is hallenge . Plasmodium pre-erythrocytic antigens would induce cell-mediated immune responses [P. falciparum pre-erythrocytic stage that are predominantly targeted by the CD8 T cells [P. falciparum (T9/96 strain) pre-erythrocytic-stage protein, thrombospondin-related adhesion protein (TRAP) to make ME-TRAP [Plasmodium parasite in the mammalian host [Another strategy used to formulate an antigen-subunit vaccine for malaria is to utilize viral vectors to deliver the antigens. Homologous or heterologous prime-boost vaccinations using viruses encoding the esponses . One of esponses ,51,52 an T cells . ME is f ME-TRAP  that tarian host . Although priming with FP9-ME-TRAP followed by MVA-ME-TRAP booster induced antigen-specific CD4 and CD8 T cell responses, only two out of the five vaccinated subjects were protected . This rePfCSP with a truncated C-terminal lacking the 14 amino acids corresponding to the CSP GPI anchor moiety [PfTRAP with the highly conserved merozoite proteins, liver-stage antigen 1 (LSA1) and the liver-stage-associated protein 2 (LSAP2), was developed. Nevertheless, neither its immunogenicity nor protective efficacy were significantly impacted with the inclusion of these two proteins [Other alternatives to the ME-TRAP antigen have been explored for antimalarial viral-vector vaccines. One of these is CSVAC, which encodes r moiety . ChAd63/r moiety ,58 sinceproteins ,60,61.Plasmodium antigens, as they are identified, into the viral vectors may change this. Additionally, a combination of viral-vectored malaria vaccines with RTS, S/AS01 may also improve the overall vaccine efficacy by the generation of protective CD8 and CD4 T cell responses along with the strong anti-CSP antibodies. The relative success of the viral-vectored malaria vaccines is promising due to their ability to induce high levels of T cell responses. Yet, their efficacy in the malaria-endemic regions have been less than ideal. It is possible that inserting more immunogenic Plasmodium has been considered an attractive target antigen for the development of pre-erythrocytic malaria vaccines. CelTOS is a 25-kDa protein vital for the ookinete traversal in the mosquito midgut, as well as for the sporozoite infection of liver cells in the human host, which also primes a strong immune response [Plasmodium species [PfCelTOS adjuvanted with Montanide ISA 720 resulted in potent humoral and cellular immune responses that induced cross-reactive immunity against P. berghei sporozoite challenge [PfCelTOS when formulated with suitable adjuvants would induce high-affinity antibodies that inhibit P. falciparum infection of Anopheles stephensi mosquitos [PfCelTOS may be an effective vaccine to not only prevent clinical infection in the human host but also transmission of the infection to and from mosquitos. Despite the positive results, the CelTOS vaccine will require more refinement before being considered a potential malaria vaccine. Besides the CSP and TRAP proteins, the cell-traversal protein for ookinetes and sporozoites (CelTOS) of response . Additio species ,64. In bhallenge . More reosquitos , suggestPlasmodium parasites. For instance, the RTS, S/AS01 vaccine efficacy is noticeably lower when challenge infections do not match the 3D7 strain-derived CSP isotype. By combining multiple antigens from different stages of Plasmodium development in the mammalian host, targeting highly conserved Plasmodium antigens with fewer polymorphisms or using novel adjuvants that induce stronger innate and adaptive immune response, some of the deficiencies of subunit antimalarial vaccines may be overcome at least partially. A key deficiency of subunit vaccines is their inability to generate long-standing immunity. Novel adjuvants and vaccine delivery platforms may help induce long-lived plasma cells to help improve the longevity of subunit vaccine-induced memory responses. This was demonstrated by the partial success of the preclinical study combining the FP9 and the MVA viral vectors with a CSP-based Hepatitis B virus core particle . AnotherP. falciparum infection initiated by the sporozoites, when arrested in its liver stage of development, provide immunity from P. falciparum challenge in humans [Plasmodium infection can be prevented from causing clinical malaria by using either chemoprophylactic antimalarial drugs that are specific to blood-stage malaria, or by using attenuated Plasmodium  parasites that prevent its progression beyond the liver. While the chemoprophylactic drugs prevent the progression of Plasmodium beyond the first round of blood-stage infection, the attenuated Plasmodium do not complete their liver-stage development and fail to enter the blood-stage altogether. It has been demonstrated that n humans . Plasmod+ CD8 T cell responses [The infection treatment vaccination (ITV) approach in malaria involves infection with wild-type sporozoites (SPZ) under the blood-stage-specific antimalarial drug coverage. Compared to the other whole-sporozoite vaccination approaches, the presence of an abortive blood-stage infection in ITV offers the added advantage of the generation of humoral immune responses against blood-stage malaria antigens. Rodent studies indicated that ITV with chloroquine (CQ) offered protection through the generation of IFN-esponses  directedesponses . P. falciparum, indicating the inadequacy of this approach to protect against the parasite’s genetic diversity [The early human whole-sporozoite vaccination studies began with controlled human malaria infections (CHMI) in conjunction with CQ prophylaxis to prevent blood-stage malaria infection. This immunization method was shown to be protective against homologous strain challenges in 100% of the vaccinated volunteers , with soiversity . New phaiversity . Neverthiversity  and the Plasmodium sporozoites induces DNA damage in the parasites, leading to the early arrest of its development in the liver. The RAS vaccine contains gamma-irradiated SPZ isolated from the salivary glands of infected mosquitos [P. yoelii RAS to confer protection, suggesting that the IV route of administration is the most efficient to generate T cell responses in animal models [P. falciparum RAS was crucial to induce high levels of circulating and liver-resident P. falciparum-specific CD8 T cells in macaques [P. berghei RAS were also protected from both homologous and heterologous (with P. vinckei) [Gamma irradiation of osquitos . Inoculaosquitos ,78. In tosquitos . Notablyl models ,81,82. Amacaques . Mice imvinckei)  species P. falciparum RAS in humans relied on immunization via mosquito bites [P. falciparum RAS showed that it reduced the risk of malaria infection in malaria-endemic regions, with the protective immunity being associated with robust P. falciparum specific CD8 T cell responses [The first clinical trials with to bites ,85. Althto bites . Intraveesponses . Althougesponses . This haPlasmodium parasites. By modifying or deleting key essential genes, Plasmodium parasites were generated that were incapable of transitioning from its liver-stage to the blood-stage of infection, thereby preventing the onset of clinical malaria. This approach to attenuate Plasmodium can be tailored to not affect the viability of Plasmodium in its blood-stage and the mosquito vector, infectivity in the mosquitoes, or the transition to the sporozoite stage, to together facilitate generating the transgenic parasites [Plasmodium also generates a homogenous population of attenuated parasites with a distinct genetic identity. The attenuated status of this unique clonal population also does not rely on external technical variables like the radiation dosage (in RAS) or host drug metabolism (in ITV) [Considering the relative success of the whole-sporozoite based vaccines, novel advances in genetic manipulation were used to develop a targeted approach to attenuate arasites . Targete(in ITV) ,90,91. Plasmodium parasites beyond its liver stage, a differential gene expression study was performed [Plasmodium liver-stage, were identified as possible targets for gene disruption based on this strategy. In mice, P. berghei (Pb) liver-stage development was disrupted in both uis3 (Pb uis3KO) [uis4 (Pb uis4KO) [Pb uis4KO and was thus not a viable vaccine candidate. Immunization of mice with double-knockout of uis3 and uis4 (Pb uis3/uis4dKO) prevented any breakthrough parasitemia, while concurrently generating IFN-γ-producing effector and memory CD8 T cell responses that offered immune protection lasting up to 6 months [In order to identify the target genes, which when ablated would prevent the progression of the erformed ,92 in therformed . The UIS uis3KO)  and uis4 uis4KO)  single-k uis4KO) . Neverth6 months . Plasmodium species [Plasmodium parasite. In mice, although the Pb P36KO infection induced protective immunity, breakthrough parasitemia was observed [Pb B9KO also led to breakthrough infections [P. yoelii (Py) p52/p36dKO-vaccinated BALB/c mice exhibited no breakthrough parasitemia and achieved protective immunity from subsequent P. yoelii sporozoite challenge [Pb p52/p36dKO parasites, suggesting incomplete attenuation of these GAPs [P. yoelii, was ablated to generate Py sap1KO. The Py sap1KO parasites exhibited arrest of development in the liver-stage with no breakthrough parasitemia, conferring long-lasting immune protection against wild-type sporozoite infection [P36, P36p (P52) and B9 were additional candidate genes identified as targets for genetic attenuation, due also to them being highly conserved among the different  species . All throbserved . Similarfections . Howeverhallenge . Breakthese GAPs . Anothernfection . Pb slarpKO showed similar results to Py sap1KO, arresting early in liver-stage development with no breakthrough parasitemia [Py slarp1KO immunization did not confer long-lasting protective immunity [FabB/F gene involved in fatty acid synthesis resulted in P. yoelii parasites that arrested late in the liver stage [Py FabB/FKO elicited a high magnitude of CD8 T cell effector and memory response in both inbred and outbred mice [An ortholog of SAP1 called SLARP was also studied, and asitemia . Howeverimmunity . The deler stage . Immunizred mice . When cored mice . This fired mice .P. falciparum lacking the two genes—p52 and p36. The Pf p52/p36dKO inoculation by mosquito bite was well-tolerated, but one out of the six volunteers develop breakthrough blood-stage malaria infection [Pb p52/p36dKO parasites [PfGAP3KO) was subsequently created, deleting p52, p36, and sap1 to further reduce the chances of breakthrough parasitemia. Administration of PfGAP3KO by mosquito bites in volunteers showed no breakthrough blood-stage P. falciparum infection. Considerable anti-CSP antibody titers were generated in all test subjects with significant IFN-γ, IL-2 and TNF cytokine levels detected in the serum [PfGAP3KO, another GAP vaccine was developed, called the PfSPZ-GA1, lacking B9 and SLARP [PfSPZ-GA1 offered acceptable safety profiles in Phase I/IIa clinical trials, only three out of the 25 vaccinated volunteers showed protective immunity to mosquito-bite challenge [The first clinical trial using GAPs evaluated the safety and immunogenicity of nfection , similararasites . A triplhe serum . Inspirend SLARP . Althoughallenge .Plasmodium beyond its liver-stage of development, they are seen as better pre-erythrocytic malaria vaccines compared to irradiated sporozoites. GAP vaccines are also homogenously attenuated and more broadly immunogenic, making it the safer and better choice for field application [Given that GAP vaccines are, by design, precisely genetically engineered to prevent the progression of lication . By idenlication ,107,108.lication . Transgelication . The logPlasmodium parasite, presence of multiple, antigenically distinct life cycle stages in the mammalian host, the involvement of mosquito vectors and the prevalence of malaria in the poorest, most populous parts of the world are just a few of these. These have also impeded our ability to understand malaria biology and effectively pursue vaccination strategies to combat this disease. Gaining a better mechanistic understanding of the immune responses mounted against Plasmodium infection might help us devise suitable vaccination approaches that effectively prevent the infection. A deeper understanding of Plasmodium development in its pre-erythrocytic stage may help unveil novel antigenic targets, amenable to improved vaccination approaches. Together, these can help develop new immunization strategies for the induction of a more effective and functional protective immunity to malaria. Despite the challenges, a great deal of progress has been made in the field of malaria vaccinology. We have made great strides in identifying and testing novel vaccine candidates and resolving the immunological metrics of protection in human and animal models [Plasmodium infection in the liver to prevent the onset of blood-stage malaria, the possibility of developing a clinically applicable, highly effective, conventional subunit vaccine against malaria appears less likely. Although live-attenuated vaccination approaches hold the most promise in terms of inducing protective immune responses at the moment, we have ways to go before these can be safely deployed in the field. We believe that future studies that systematically dissect the immunobiology of liver-stage malaria will help drive the design, development and optimization of effective immunization strategies that will one day help eradicate malaria.The field of malaria vaccine development has faced many challenges over the years. The genetic and biological complexities of the l models ,110. Bas


Understanding the relationship between malaria infection risk and disease outcomes represents a fundamental component of morbidity and mortality burden estimations. Contemporary data on severe malaria risks among populations of different parasite exposures are scarce. Using surveillance data, we compared rates of paediatric malaria hospitalisation in areas of varying parasite exposure levels.Surveillance data at five public hospitals; Jinja, Mubende, Kabale, Tororo, and Apac were assembled among admissions aged 1 month to 14 years between 2017 and 2018. The address of each admission was used to define a local catchment population where national census data was used to define person-year-exposure to risk. Within each catchment, historical infection prevalence was assembled from previously published data and current infection prevalence defined using 33 population-based school surveys among 3400 children. Poisson regression was used to compute the overall and site-specific incidences with 95% confidence intervals.Plasmodium falciparum prevalence varied across the five sites. Current prevalence ranged from < 1% in Kabale to 54% in Apac. Overall, the malaria admission incidence rate (IR) was 7.3 per 1000 person years among children aged 1 month to 14 years of age . The lowest rate was described at Kabale  and highest at Apac . There was a correlation between IR across the five sites and the current parasite prevalence in school children, though findings were not statistically significant. Across all sites, except Kabale, malaria admissions were concentrated among young children, 74% were under 5 years. The median age of malaria admissions at Kabale hospital was 40 months , and at Apac hospital was 36 months . Overall, severe anaemia (7.6%) was the most common presentation and unconsciousness (1.8%) the least common.Both current and historical Malaria hospitalisation rates remain high in Uganda particularly among young children. The incidence of hospitalized malaria in different locations in Uganda appears to be influenced by past parasite exposure, immune acquisition, and current risks of infection. Interruption of transmission through vector control could influence age-specific severe malaria risk. Despite reductions in the risk of malaria infection, morbidity and mortality across sub-Saharan Africa (SSA) over the last two decades, gains have not been uniform in the region , 2. Six During the 1990s and early 2000s the relationship between the frequency of malaria parasite exposure and severe disease incidence was the subject of intense investigation across different transmission settings in African –12. ThesIn Uganda, despite a reduction in national under-five malaria prevalence from 30.4% in 2016  to 16.9%In 2010, the Uganda Malaria Surveillance Project (UMSP), in collaboration with the National Malaria Control Programme (NMCP), established an inpatient malaria surveillance program in the children’s wards at six public hospitals –27. ThesIn 2016, the inpatient malaria surveillance program was expanded to provide a platform for investigation of aetiologies of Acute Febrile Illnesses (AFI) . ImproveThe present study focused on a retrospective analysis of admissions to five hospitals from 2017 to 2018 among children aged 1 month to 14 years from communities located close to five hospitals shown in Fig. Patient diagnoses were made at admission and at discharge. A check list of most common diagnoses was incorporated in the MRF. Upon evaluation of patients, based on their judgment informed by history, examination findings and available test results, clinicians checked one or more diagnosis. It was not unusual for children to have more than one diagnosis; occasionally complications of illness were listed as diagnoses. A free text field was included for recording diagnosis not included in the list of available diagnosis. Patients who had any record under the possible diagnoses, or notes, of AIDS, TB, Sickle Cell Disease, epilepsy, congenital malformations, poisoning, burns, trauma, snake or animal bites, elective surgery or measles were immediately excluded from the data series, irrespective of whether they had a diagnosis of malaria. Here we presumed the underlying conditions to be the primary cause for admission and malaria a coincidental diagnosis. Patients who had any record of malaria were then identified and checked against malaria test (microscopy or mRDT) results, those who had a negative malaria test results were reclassified as unknown or replaced by other diagnoses if reported.Malaria admissions were further classified according to the criteria of severe malaria approximating to those defined by the WHO  includinA variety of information on each patient’s residential address was available on the MRF. This information was used to locate residential parishes (third level census administration areas). Lists of village names per parish, Google Earth and other digital place name gazetteers  were useThe selected parishes were then used to extract total population counts from the 2014 national census , projectTo understand the role of parasite exposure on the epidemiology of severe malaria risks both historical and current infection prevalence were defined. It was not possible to identify specific survey data on community-based malaria prevalence for each of the catchment areas selected for the present study. However, district-wide survey data undertaken between 2010 and 2016 among children aged less than 15 years, where at least 15 children had been examined with microscopy were identified from previous datasets  updated To represent contemporary infection prevalence, school-based surveys within the catchment parishes selected for the 2017–2018 surveillance period were undertaken at the end of the hospital recruitment period in 2019. School children provide a simple, reliable source of community-level malaria prevalence , 43. CatAll clinical data were stored on the DHIS-2 platform and school data were double entered using EpiData (v3.1). Data analysis was performed in STATA  and R version 3.6.1 (R Core Team (2019), Vienna, Austria). Patient’s demographics were summarised as proportions and median ages with interquartile range (IQR). Kruskal Wallis was used to test for differences in median age. The incidence rate (IR) of hospitalised malaria was defined as the number of cases with a primary diagnosis of malaria (confirmed by microscopy or mRDT) divided by person-years of observation expressed per 1000 people. Since re-admissions were not documented all malaria admissions were included in the IR calculation, and therefore strictly best referred to as period prevalence. The prevalence of each severe malaria phenotype was defined as the number of hospitalised children with a specified severe malaria phenotype divided by the number of all hospitalised children without missing information required to classify by that phenotype. The age specific, site specific, and syndrome specific IR with 95% confidence intervals were computed using the exact Poisson distribution. Poisson regression was used to compute the incidence rate ratios (IRR) for the age groups < 1 year, 1–4 years, 5–9 years and 10–14 years, adjusted for site. The association between parasite prevalence and IR of malaria hospitalisation was determined using a Spearman rank correlation coefficient (rho) and confidence intervals constructed using Fisher’s z transformation.The five rural, catchment parishes used to define hospital admission rates are shown in Table The five selected hospital sites Fig.  and the Plasmodium falciparum slide positivity in Kabale to 54% in Apac  across the combined sites was 7.3  per 1000 children 1 month to 14 years per annum. The annualized rates of malaria hospitalisation varied significantly between hospital catchments, with the lowest rates observed at the very low transmission site at Kabale  and the highest at Apac  (Table p < 0.001) and among those aged 10–14 years  as compared to children aged 1–4 years after adjusting for site , 1257 (73.6%) of all admissions were aged less than 5 years. Children presenting to Kabale hospital had the highest median age , followed by Apac  and the remaining sites the median age of the malaria admissions was between 27 and 30 months (Table p = 0.19). The association remained unchanged even when we restricted the rates of admission to children aged 1–23 months of age , a period most likely representative of current transmission intensity  Fig. , althougp < 0.001)  was the least common severe disease phenotype among all admissions. However, unconsciousness was present in 1/6 of the admissions at Kabale and was more common in Mubende  compared to other sites . Consistent with earlier observations in high transmission settings in Africa during the 1990s-early 2000s –12, ApacSince 2014, the traditionally high transmission  of age group adjusted for site obtained from a Poisson regression model.Additional file 2: Supplement S2. Malaria admission rates for children aged 1 month-23 months per 1000 person-years of observation versus school-based malaria parasite prevalence at the end of the surveillance period.


Intermittent preventive treatment of malaria during pregnancy (IPTp) with dihydroartemisinin-piperaquine (DP) significantly reduces the burden of malaria during pregnancy compared to sulfadoxine-pyrimethamine (SP), the current standard of care, but its impact on the incidence of malaria during infancy is unknown.We conducted a double-blind randomized trial to compare the incidence of malaria during infancy among infants born to HIV-uninfected pregnant women who were randomized to monthly IPTp with either DP or SP. Infants were followed for all their medical care in a dedicated study clinic, and routine assessments were conducted every 4 weeks. At all visits, infants with fever and a positive thick blood smear were diagnosed and treated for malaria. The primary outcome was malaria incidence during the first 12 months of life. All analyses were done by modified intention to treat.p = 0.11). Stratifying by infant sex, IPTp with DP was associated with a lower incidence of malaria among male infants  but not female infants .Of the 782 women enrolled, 687 were followed through delivery from December 9, 2016, to December 5, 2017, resulting in 678 live births: 339 born to mothers randomized to SP and 339 born to those randomized to DP. Of these, 581 infants (85.7%) were followed up to 12 months of age. Overall, the incidence of malaria was lower among infants born to mothers randomized to DP compared to SP, but the difference was not statistically significant  0.87, 95% confidence interval (CI) 0.73–1.03, Despite the superiority of DP for IPTp, there was no evidence of a difference in malaria incidence during infancy in infants born to mothers who received DP compared to those born to mothers who received SP. Only male infants appeared to benefit from IPTp-DP suggesting that IPTp-DP may provide additional benefits beyond birth. Further research is needed to further explore the benefits of DP versus SP for IPTp on the health outcomes of infants.NCT02793622. Registered on June 8, 2016.ClinicalTrials.gov,  Plasmodium falciparum the predominant species. In 2018, there were an estimated 39 million pregnancies in sub-Saharan Africa, of which over 11 million (29%) were exposed to P. falciparum [P. falciparum during pregnancy. However, even in the absence of symptomatic disease, malaria in pregnancy is associated with maternal anemia and adverse birth outcomes such as low birth weight, preterm delivery, and stillbirth [Infection with malaria parasites during pregnancy remains a major public health problem, especially in sub-Saharan Africa where transmission intensity is highest and illbirth .To prevent malaria in pregnancy and improve birth outcomes, the World Health Organization (WHO) recommends intermittent preventive treatment (IPTp) with sulfadoxine-pyrimethamine (SP) in pregnant women residing in areas of moderate to high malaria transmission intensity . HoweverP. falciparum may negatively affect the development of antimalarial immunity in the infant [Prevention of malaria during pregnancy may have additional benefits to the infant beyond the neonatal period. Studies have shown that intrauterine exposure to e infant , 11. Inde infant –14. Howee infant , 16 or te infant .To address this gap in evidence, we compared the incidence of malaria during the first year of life among infants born to HIV-uninfected pregnant women who took part in a double-blind randomized controlled trial of monthly IPTp with DP (a highly effective regimen) versus SP (a less effective regimen). During pregnancy, IPTp-DP was superior to IPTp-SP at reducing the incidence of clinical malaria and prevalence of asymptomatic parasitemia during pregnancy, and the prevalence of placental malaria at delivery . ChildreThis study was conducted from September 6, 2016, to December 4, 2018, in Busia district, south-eastern Uganda, an area of high malaria transmission intensity. The study was conducted in two phases: the pregnancy phase, which involved enrollment and follow-up of pregnant women through delivery, and the infancy phase, which involved follow-up of infants through 12 months of age. Details of the pregnancy phase of the study have been published elsewhere . In brieThis was a double-blind randomized controlled trial designed to assess the impact of monthly IPTp with DP versus SP in HIV-uninfected pregnant women, on the incidence of malaria during infancy . At enrollment, pregnant women were randomly assigned in a 1:1 ratio to receive IPTp-DP or IPTp-SP. A randomization list was computer generated using permuted blocks of 4 or 8 by a staff member not directly involved in patient care. To achieve allocation concealment, sealed envelopes, each containing a treatment allocation number and treatment group assignment, were prepared following the sequence of the randomization list, prior to enrollment. Treatment allocation was done by a study pharmacist not involved in daily patient care by picking the next available sealed envelope, recording the participant’s identification number on the envelope, and opening it to reveal the assigned treatment. The treatment allocation number, the participant’s identification number, and the assigned treatment were then recorded on a treatment allocation log which was kept in a safe lockable place only accessible by the study pharmacist. Study drugs for each enrolled participant were pre-packaged by the study pharmacist and labeled with the participant’s identification number. Study drugs were administered every 4 weeks starting at 16 or 20 weeks of gestation. Each dose of DP  consisted of 3 tablets given once a day for 3 consecutive days. Each dose of SP  consisted of 3 tablets given as a single dose. To achieve blinding, participants randomized to DP also received SP placebos, and participants randomized to SP received DP placebos every 4 weeks. The administration of all 1st daily doses of study drugs was directly observed in the study clinic. The 2nd and 3rd daily doses were dispensed to the mother for self-administration at home. Adherence to the 2nd and 3rd daily doses was assessed by self-reporting during the visits following routine visits.Study procedures for pregnant women have been previously described in detail . Briefly> 38.0 °C had blood collected for a thick blood smear. If the thick blood smear was positive, infants were treated for malaria according to the Uganda Ministry of Health guidelines which consisted of artemether-lumefantrine for uncomplicated malaria and intravenous artesunate for complicated malaria. Non-malarial illnesses were treated according to the integrated management of childhood illnesses guidelines. At 12, 28, and 52 weeks of age, blood was collected for hemoglobin measurement.Following delivery, all live births were followed up to 12 months of age. Mothers were encouraged to bring their infants to a dedicated study clinic open every day for all their medical care and were provided a transport refund. Routine assessments were conducted every 4 weeks including the collection of blood for the detection of parasites by microscopy. Infants who presented with a history of fever in the past 24 h or with a documented tympanic temperature The presence of malaria parasites in dried placental blood spots was detected by loop-mediated isothermal amplification as previously described . PlacentThe primary outcome was the incidence of malaria from birth to 12 months of age. An incident episode of malaria was defined as the presence of fever (history of fever in the past 24 h or a tympanic temperature ≥ 38.0 °C) with a positive thick blood smear not preceded by another malaria episode in the last 14 days. Secondary outcomes included time to the first episode of malaria, incidence of complicated malaria defined as an episode of malaria with danger signs  or the meeting standardized criteria for severe malaria, incidence of all-cause hospitalizations, infant mortality, incidence of non-malarial febrile illnesses, prevalence of malaria parasitemia during routine visits, and prevalence of anemia (hemoglobin < 10 g/dL) at 12, 28, and 52 weeks of age.To test the hypothesis that infants born to mothers randomized to IPTp-DP would have a lower incidence of malaria during the first 12 months of life compared to infants born to mothers randomized to IPTp-SP, it was estimated that the incidence of malaria in infants born to mothers randomized to IPTp-SP would be 3–5 episodes per person-year  were defined as the incidence in the IPTp-DP arm divided by the incidence in the IPTp-SP arm. Prevalence ratios were defined as the prevalence in the IPTp-DP arm divided by the prevalence in the IPTp-SP arm. Stratified analyses of our primary outcome according to infant sex and age, and maternal gravidity were planned a priori in the statistical analysis plan. The cumulative risk of the first episode of malaria was compared using a Cox proportional hazards model with the association expressed as the hazard ratio (HR). In all analyses, two-sided p values of < 0.05 were considered statistically significant.Data were double entered and verified in Microsoft Access by two independent data entrants. Using Stata, version 14.2, statistical analyses were done in the modified intention-to-treat population, which included all live births followed until they reached 12 months of age or premature study withdrawal. Comparisons of simple proportions were made using the chi-square test or Fisher’s exact test. Comparisons of continuous variables were made using the N = 391) or SP (N = 391) . Similarly, the incidence of malaria during pregnancy was significantly lower in mothers who received IPTp-DP compared to mothers who received IPTp-SP . At delivery, compared to mothers who received IPTp-SP, mothers who received IPTp-DP had a significantly lower prevalence of placental parasitemia detected by histology . There was no difference in the incidence of malaria between female infants born to mothers who received IPTp-DP versus IPTp-SP  but not between 0 and 3 months of age . There were no differences between the IPTp regimens among female infants stratified by age (Table p = 0.30). When stratified by infant sex, male infants born to mothers who received IPTp-DP had a lower rate of the first episode of malaria compared to male infants born to mothers who received IPTp-SP, but this did not reach statistical significance  and there was no difference among female infants  compared to infants born to mothers who received IPTp-SP (1.98 episodes per person-year), but the difference was not statistically significant (incidence rate ratio (IRR) 0.87, 95% confidence interval (CI) 0.73–1.03, p = 0.02; Table p = 0.01). There was no significant difference in the incidence of complicated malaria between female infants born to mothers who received IPTp-DP or IPTp-SP .Overall, there were 68 episodes of complicated malaria among 59 different infants. For 60 episodes of complicated malaria, only danger signs were present while 8 episodes met the criteria for severe malaria (7 episodes of respiratory distress and 1 episode of severe anemia). The incidence of complicated malaria was lower among infants born to mothers who received IPTp-DP compared to those born to mothers who received IPTp-SP . When stratified by sex, male infants born to mothers who received IPTp-DP had a statistically significantly lower incidence of all-cause hospitalizations compared to male infants born to mothers who received IPTp-SP , but there was no difference among female infants . A total of 16 infants died, including 9 in the neonatal period. One infant born to a mother who received IPTp-DP died of malaria at 11 months of age. There was no significant difference in the mortality rate between infants born to mothers who received IPTp-DP or IPTp-SP . The incidence of non-malarial febrile illnesses was similar among infants born to mothers who received IPTp-DP or IPTp-SP. The prevalence of parasitemia during routine visits and prevalence of anemia (hemoglobin< 10 g/dL) measured at 12, 28, and 52 weeks of age were similar among infants born to mothers who received IPTp-DP or IPTp-SP. Considering the time to the first parasitemia, there was no significant difference between infants born to mothers who received IPTp-DP and those born to mothers who received IPTp-SP . When stratified by infant sex, male infants born to mothers who received IPTp-DP had a slightly lower rate of first parasitemia compared to male infants born to mothers who received IPTp-SP, but this did not reach statistical significance  and there was no difference among female infants .The incidence of all-cause hospitalizations was lower among infants born to mothers who received IPTp-DP compared to infants born to mothers who received IPTp- SP, but this did not reach statistical significance  was lower than the assumed incidence of 3–5 episodes per person per year which was used for sample size estimation. This limited the power of the study to detect a significant difference between the two IPTp arms if such a difference truly existed. Also, our study was not powered to conduct stratified analyses by infant sex and age, or to test for associations between IPTp-DP and secondary outcomes such as complicated malaria and all-cause hospitalizations, which were relatively uncommon in our study. Therefore, statistically significant associations observed in stratified analyses and between IPTp-DP and secondary outcomes should be interpreted with caution. This study was conducted in an area with very high malaria transmission intensity, as at enrollment over 80% of mothers had malaria parasitemia detected by microscopy or quantitative PCR [In summary, our study findings show that in addition to reducing the burden of malaria during pregnancy and placental malaria at delivery compared to monthly IPTp-SP , monthly


Malaria is commonly associated with alteration in haematologic cells of infected individuals in both the acute uncomplicated and severe phases. Whether this alteration occurs in the asymptomatic phase of the disease is still being investigated.To examine the haematocrit, thrombocytes, and monocytes levels of children with asymptomatic malaria compared with age/sex-matched controls who are malaria parasite negative and living in a stable malaria endemic region. It also set out to identify spleen rate of the children and to compare it with that observed in malaria negative controls.One hundred well-nourished children 2–9 years old with asymptomatic malaria parasitaemia and 100 age- and sex-matched malaria negative controls were recruited by multi-stage sampling from schools in a malaria endemic region of Nigeria. Malaria diagnosis was by microscopy, and each haematologic parameter was analysed following standard protocols.9 cells/L observed in asymptomatic malaria children was significantly higher than 1.34 ± 0.5 × 109 cells/L observed in those with no malaria (p = 0.00). Mean (±) thrombocyte count was significantly lower  (p = 0.00). Spleen rate in the children was 15.5%. Presence of splenomegaly was not statistically significantly fewer in children with asymptomatic malaria parasitaemia (ASMP) (14/31) when compared to those who were malaria parasite negative (17/31) . Similarly, there was no significant difference in the mean [±] spleen length of children with ASMP  and those who were malaria negative  .Mean (±) monocyte count of 2.25 ± 0.9 × 10Thrombocytopaenia and monocytosis could be pointers to malaria parasitaemia in asymptomatic phase in a stable malaria region. Malaria is a blood vector-borne disease with high morbidity and mortality in children in sub-Saharan Africa . The 2011Malaria disease is commonly associated with alterations in haematologic cells of the peripheral blood of infected individuals in both the acute uncomplicated and severe phases 4. The ha436Anaemia is a complication contributing significantly to mortality from malaria disease 45678. Th45674445488911In most stable malaria endemic (high transmission) regions, the disease is largely asymptomatic 1314. It 1314Although some studies had reported haematologic parameters of children with asymptomatic malaria, their findings were inconsistent. Most of these reports did not consider factors such as age/sex-match healthy population, nutritional status, and spleen rate of the study population.This present study, therefore, reported haematologic parameters  of well-nourished school children  with ASMP and malaria parasite negative age- and sex-matched controls. The study also reported spleen rate in well-nourished school children, as well as comparing the spleen rate between children with ASMP and malaria negative age- and sex-matched controls.Are there differences in the levels of haematocrit, thrombocytes, and monocytes of well-nourished healthy children (2–9 years) with asymptomatic malaria and age/sex matched control with negative parasitaemia?What is the relationship (if any) between these haematologic parameters and spleen rate in the study population?Is there a correlation between the levels of these haematologic parameters and spleen length (size) in the study population?There is no statistically significant difference in the levels of the haematologic parameters  of well-nourished children with asymptomatic malaria parasitaemia and age/sex-matched healthy controls with negative parasitaemia. There is also no statistically significant correlation between in the level of these haematologic parameters and spleen size (length in cm) in the study population.There is a statistically significant difference in the haematologic  levels of well-nourished children with asymptomatic malaria parasitaemia and age/sex-matched healthy controls with negative parasitaemia. There is also a statistically significant correlation (either negative or positive) between the levels of these haematologic parameters and spleen size (length in cm) in the study population.This was an observational analytic study carried out in school children aged 2–9 years recruited by multi-stage sampling in nursery and primary schools from 3 political wards in a local government located in Edo State Nigeria. The study location lies within the rain forest geographic region of Nigeria with an average annual temperature range of 27°C to 36°C, an annual rainfall of 3,500mm, and relative humidity of over 80.0% . ParticiEthical clearance for the study was obtained from the Research and Ethics Committee of the University of Benin Teaching Hospital, Benin, while written permissions to access the schools were obtained from the Edo State Ministry of Education and the heads of the selected schools. Also, written informed consents were obtained from parents/guardians/caregivers of all selected participants.Two hundred apparently healthy nursery and primary school pupils aged 2–9 years in Egor Edo South District Nigeria that satisfied the inclusion criteria for the study were recruited from the selected public and private schools. Inclusion criteria included (a) well-nourished children by the z-score for weight for age being within the 2-standard deviation for age/sex WHO growth chart, (b) the children would not have had treatment for malaria in the two weeks preceding the study, and (c) there is no history of fever at the time of recruitment. Excluded from the study were (a) children who were on antimalarial chemoprophylaxis during period of recruitment, as these could interfere with malaria parasites density; (b) children who had been diagnosed or had clinical features suggestive of sickle cell anaemia (SCA), SCA is a known cause of splenomegaly; (c) children who had received blood transfusion in the preceding three months. This is because the life span of red blood cells is three months to ensure that the assessed haematologic parameters were those of the index study participants.Sample size calculation of 200 children based on effect size as outlined by Statistics Solutions at α = 0.05, β = 0.2 and a power of 0.80 . These 2There were 10 political wards in the selected local government area, namely Edaiken, Egor, Evbareke, Evhuotubu, Okhoro, Oliha, Ugbowo, Useh/Ogida, Uwelu, and Uselu. Three of the 10 wards were selected by simple random method using balloting technique. The three selected wards were Edaiken, Uwelu, and Ugbowo.There were 20 registered public and 10 registered private primary schools with nursery units in the three selected wards. Using the method proposed by Henderson et al.,  one thirFor the public schools, the sampling interval was calculated by dividing the total number of public primary schools in the 3 selected wards, which was 20, by the selected number of public primary schools, which was 6; equal to 3. The same was applicable with the private schools, where the sampling interval was calculated by dividing the total number of private primary schools in the 3 selected wards, which was 10, by the selected number of private primary schools, which was 3; giving 3.3, which was approximated to 3.Therefore, from the 20 public schools in the 3 selected wards arranged in alphabetical order, the first school was selected by random technique, and thereafter, every other third school on the list was selected, and a total of 6 public schools were selected for the study. Similarly, 3 private schools were selected from the 10 registered private schools.The selected public schools were labeled A, B, C, D, E, and F, and the selected private schools were labeled A1, B1, and C1.The total sample size of 200 was distributed proportionately among the selected public and private schools by the process shown below:1 = Sample size for each selected schoolwhere: na = Population of pupils in index schoolb = Total population of pupils in all selected schoolsc = Calculated study sample sizeThe pupils were then selected from each school using the above formula until the entire sample size was reached.The selected children in each school were stratified into age groups pre-school (2 to < 5 years) and school age (5–9 years). The specific age strata sample size was calculated for each school using the formula:2 = Age bracket sample size for each selected schoolwhere: na = Population of pupils of index age bracket in index schoolb = Total population of pupils in the index schoolsc = Calculated sample size for index schoolThe class in each school from which the children were selected was determined by simple random sampling technique. The class register served as sampling frame from which each pupil was selected. Each selected pupil was given an informed consent form to be completed by their parents or caregiver. All selected pupils whose parents signed the informed consent were recruited into the study. In cases where a parent/guardian declined consent, the next child on the register was selected until the desired number was obtained. After obtaining a positive malaria positive result, the paired age group and sex matched negative in the same class was selected as control until the selected sample from that school was completed. This process was carried out in all the selected schools until the 100 children on both arms  were selected.At recruitment, a questionnaire developed by the authors, which was pre-tested on 20 pupils/parents from one of the schools that was not selected for the study, was administered to the parent/guardian of each child who fulfilled the selection criteria. Information on the questionnaire included data on socio-demographics, long-lasting insecticidal nets (LLIN) ownership and usage. A physical examination, including a general examination, measurement of temperature, anthropometry (weight and height), and abdominal examination were conducted and recorded in the study pro forma. The temperature of each pupil was measured using a clinical mercury-in-glass thermometer and the axillary temperature recorded in degrees Celsius after leaving the thermometer for a period of two minutes.The anthropometric indices measured in the children was weight and height. Weight of the children was obtained as follows:The participants were weighed using a Seca® Scale  with a precision to the nearest 0.1 kg. Each participant was weighed as follows:Shoes and outer clothing were removed.The scale was turned on by covering the solar panel for a second. When the number 0.0 appeared, the scale was ready.The child was asked to stand in the middle of the scale, feet slightly apart , and to remain still until the weight appeared on the display.The child’s weight was recorded to the nearest 0.1 kg.The height of each child was taken using a standiometer with a precision to the nearest 0.1 cm. The height of each subject was measured as follows: each child was positioned erect, barefeet, with legs together, shoulders, buttocks, and heels touching the upright backboard and the child instructed to look straight ahead. The movable headpiece was brought onto the vertex of the head with sufficient pressure to compress the hair and the height was recorded to the nearest 0.1 cm.The presence of splenic enlargement and the spleen length of all the children were assessed by bimanual palpation  by one oBlood samples were collected into containers with ethylene diamine tetra acetate (EDTA) anticoagulant using strict aseptic procedure. Each specimen bottle was labelled with each participant’s identification number as recorded on the questionnaire administered at recruitment. The venepuncture site was swabbed twice with methylated spirit and venous access gained with a 21G sterile hypodermic needle. One milliliter (1ml) of blood was withdrawn from each participant and transferred into the EDTA bottle to prevent clotting. Haemostasis was secured after the procedure by applying pressure to the venepuncture site with a clean dry swab. All samples for the day were transported to the Department of Child Health, UBTH Research Laboratory in an ice-packed polythene container with cork-screwed lid. The samples were used for preparation of the thick and thin smears for malaria parasite determination by the methods prescribed by Cheesbrough . All filHaematologic parameters  analyses were performed following standard protocols.9/L), and monocytosis (monocyte count more than 1.0 × 109/L). Comparison of mean of quantitative variables, such as age and spleen length of the children and malaria parasite count, was done using independent t-test. Chi-square was used to test association between non-parametric variables, such as sex, family social class, household size, use of long-lasting insecticidal nets, and presence of malaria parasite and splenomegaly, respectively. Pearson’s correlation was used to identify the relationship between malaria parasitaemia count and spleen length. The level of significance for each variable was set at p < 0.05 and confidence level at 95%.Data were generated from information  obtained from each study participant. These were coded and analysed using the Statistical Package for Social Sciences (SPSS) version 21.0. . There were two arms of the study participants, namely those with ASMP and those that were malaria parasite negative. These two groups were sex and age group matched. Households with more than five individuals were regarded as large households, while those with less than five individuals were regarded as small households . The famPlasmodium falciparum was the only malaria parasite specie observed in the children.Of the 200 children , mean (±) age was 6.6 ± 2.0 years. There were 59 (59.0%) males and 41 (41.0%) females in each arm of the study. Table 9 cells/L, and the mean (±) monocyte count was 1.80 ± 0.9 × 109 cells/L.Total mean (±) haematocrit of the study population was 34.3 ± 2.2% (range 21–40%), mean (±) platelet count was 217.3 ± 53.6 × 10Figures 2 = 0.34, p = 0.57). Similarly, there was no significant difference in the mean [±] spleen length of children with ASMP  and those with negative malaria parasite  . There was a positive correlation between MP count and spleen length; however, this positive correlation was not statistically significant .Spleen rate observed in the children was 31/200 (15.5%). Mean spleen length of the study population was 2.7 ± 0.7 (2–5) cm. Presence of splenomegaly was not statistically significant in children with ASMP (14/31) when compared to those with malaria parasite negative (17/31) . The mean (±) monocyte count was significantly higher (2.25 ± 0.95 × 109cells/L in children with ASMP) than 1.34 ± 0.5 × 109 cells/L observed in those with negative malaria parasite (p = 0.00). There was no significant difference in haematocrit levels between the two groups . There was also no significant difference in the mean haematologic parameters in children with splenomegaly and those with no splenomegaly.Table p = 0.003). The children with ASMP were 6.8 times likely to have thrombocytopaenia than the control group. Similarly, the proportion of children with ASMP who had monocytosis (77.0%) was significantly higher than the 33.0% observed in the control group, and those were nearly 7 times more likely to have monocytosis than the control group . Although there was no significant difference in the haematocrit levels between the two groups, the children with ASMP were two times more likely to develop anaemia than the control group .Table Table 2 = 7.60, p = 0.01).In the study population, 110 (55.0%) had one or more LLIN in their households and 73 used the LLIN as a means of malaria prevention, giving an LLIN usage rate of 66.4%, while 37 (33.6%) did not use LLIN. The proportion of the children who did not use LLIN  significantly had ASMP as against the proportion of children who used LLIN   . Althoug3he cells 26. MonocThe children could have been screened for helminthes, which is a known cause of monocytosis. ASMP children were treated using the recommended ACT; however, there is need to re-assess the haematologic parameters of these children after the treatment.This study has shown that there are alterations in haematocrit, platelet, and monocyte counts in ASMP. Using spleen rate, it could be concluded that malaria transmission in this study location is currently mesoendemic rather than holoendemic as had been documented in previous studies. Thrombocytopaenia and spleen rate could be included as malariometric indices in classifying malaria endemicity. Thrombocytopaenia and monocytosis could be useful parameters for identification of asymptomatic malaria parasitaemia in children.The datasets used and analysed during the current study are available from the corresponding author on reasonable request.


Plasmodium falciparum and its relation to nutritional status and haematological indices among schoolchildren in Bajil district of Hodeidah governorate, west of Yemen.Malaria, malnutrition and anaemia are major public health problems in Yemen, with Hodeidah being the most malaria-afflicted governorate. To address the lack of relevant studies, this study was conducted to determine the prevalence of P. falciparum asexual stages was estimated on thick films. EDTA-blood samples were examined for the haematological indices of haemoglobin (Hb) and blood cell counts.A cross-sectional study was conducted among 400 schoolchildren selected randomly from four schools in Bajil district. Data about demographic characteristics, risk factors and anthropometric measurements of age, height and weight were collected. Duplicate thick and thin blood films were prepared, stained with Giemsa and examined microscopically for malaria parasites. The density of Plasmodium falciparum was prevalent among 8.0% (32/400) of schoolchildren with a mean parasite density of 244.3 ± 299.3/µL of blood and most infections showing low-level parasitaemia, whereas Plasmodium vivax was detected in one child (0.25%). Residing near water collections was a significant independent predictor of falciparum malaria  in schoolchildren. Mild anaemia was prevalent among more than half of P. falciparum-infected schoolchildren and significantly associated with falciparum malaria , with a mean Hb concentration of 10.7 ± 1.0 g/dL. Although the mean values of the total white blood cells, monocytes and platelets were significantly lower in infected than non-infected schoolchildren, they were within normal ranges. More than half of the children were malnourished, with stunting (39.3%) and underweight (36.0%) being the most prevalent forms of malnutrition; 6.3% of children were wasted. Underweight  but not stunting or wasting, was a significant predictor of falciparum malaria among schoolchildren.Asymptomatic falciparum malaria is prevalent among schoolchildren in Bajil district of Hodeidah Governorate, with predominance of low parasitaemic infections and significant association with mild anaemia and underweight. Residence near water collection is a significant predictor of infection with falciparum malaria among schoolchildren. Further studies among children with severe malaria and those with high parasite densities are recommended. Plasmodium falciparum [Malaria represents a major health challenge in tropical and sub-tropical countries, including Yemen. In 2018, 228 million malaria cases and 405,000 malaria-related deaths have been estimated worldwide [lciparum . AlthougChild malnutrition is high in developing countries, particularly among rural residents . In YemeNutritional status could be a critical modulator of malaria morbidity and mortality . A recenFalciparum malaria can lead to changes in the haematological indices of infected individuals, including those related to the major cell lines of red blood cells (RBCs), white blood cells (WBCs) and platelets –21. ThesA school-based, cross-sectional study was conducted in Bajil district of Hodeidah during the malaria transmission season (November 2017 to January 2018). Malaria Unit of the NMCP in the district is one of the sentinel sites for monitoring of anti-malarial drug efficacy and resistance. Bajil district is located at the geographic coordinates of 15° 06′ N and 43° 28′ E  and at a confidence level of 95.0% and an accepted marginal error of 5.0%. However, 400 schoolchildren were included in this study. The sampling strategy adopted a two-stage sampling approach. In the first stage, cluster sampling was used, where 110 schools in Bajil were considered as the clusters of the study. These schools were listed and categorized as rural and urban, and then four schools were randomly selected. In the second stage, simple random sampling was adopted to select schoolchildren from the records of each school, with replacement of each ineligible or absent or unwilling to participate with the next one in the school record.Data about demographic characteristics  and risk factors possibly associated with malaria among schoolchildren were collected using a structured questionnaire. In addition, the axillary temperature was measured using a thermometer, and children were considered febrile if having an axillary temperature of ≥ 37.5 °C.To assess the anthropometric measurements of schoolchildren, height was measured to the nearest 0.1 cm using a height-measuring tape and weight was measured to the nearest 0.1 kg using Omron HN286 Digital Personal Scale . Age was retrieved from birth certificates or school records. Scores of height, weight and age were then recorded in the specified fields of the questionnaire.Capillary blood was collected onto clean glass slides by finger-prick to make duplicate thick and thin blood films. About 3 mL of venous blood were also collected into pre-labelled EDTA blood collection tubes  under aseptic conditions for haematological investigations.Thick and thin blood films prepared from capillary blood samples were stained with Giemsa and examined for malaria parasites using light microscopy according to standard guidelines , 24 at t9/L [Venous blood samples were examined for complete blood counts using Sysmex XP-300™ Automated Haematology Analyser  at the Haematology Laboratory of the Military Hospital at Hodeidah city. Patterns of Hb concentration (g/dL), RBC count, total and differential WBC counts and platelet count were determined. Anaemia in children was defined as Hb < 11.5 g/dL , while t9/L .t-test or Mann–Whitney U test for normally and non-normally distributed data, respectively. A binary logistic regression model was developed to identify the risk factors or predictors of falciparum malaria among schoolchildren, where odds ratios (ORs) and their corresponding 95.0% confidence intervals (CIs) were reported. This was followed by multivariable logistic regression of variables to identify the independent predictors of falciparum malaria among schoolchildren, reporting the adjusted ORs (AORs) and their corresponding 95.0% CI. Differences and associations were considered statistically significant at a p-value of < 0.05. In the present study, fever and thrombocytopaenia were excluded from the statistical analysis of association with falciparum malaria because only two out of five febrile children were infected and only one child was thrombocytopaenic (platelet count = 95 × 109/L) to avoid bias introduced by the low statistical power.Data were analysed using IBM SPSS Statistics, version 21.0 . Frequencies and proportions were used to express categorical variables and their associations or differences were tested using Pearson’s Chi-square or Fisher’s exact tests, whichever suitable. Mean ± SD and median ± interquartile range (IQR) were used to express the continuous variables with normally and non-normally distributed data, respectively. Differences between continuous variables were tested using independent Student’s Anthropometric indices derived from height, weight and age measurements were calculated and analysed using EPINUT . These were expressed as SD units or Z-scores, which were then interpreted and compared according to the growth reference curves of the National Center for Health Statistics/Centers for Disease . ChildreTable P. falciparum and Plasmodium vivax, respectively. The mean density of P. falciparum was 244.3 ± 299.3 parasites/µL of blood, where most infections (96.9%) showed low-level parasitaemia with absence of high-level parasitaemia. Gametocytes were detected in 12 cases (37.5%)  and one child (0.25%) were positive for Residence in proximity to water collections was the only factor significantly associated with increased risk of falciparum malaria among schoolchildren in bivariate analysis , which was also identified it as an independent predictor of malaria  using multivariable logistic regression Table .Table 3SP. falciparum-infected than malaria-negative schoolchildren. In contrast, no statistically significant difference was found between the two groups regarding the mean percentages of neutrophils, lymphocytes and eosinophils  was the haematological abnormality significantly associated with falciparum malaria among schoolchildren, where it was prevalent among 20.8% (83/400) of schoolchildren and 53.1% (17/32) of P. falciparum-infected ones. On the other hand, underweight , but neither stunting nor wasting, was significantly associated with falciparum malaria among the schoolchildren. Anaemia  and underweight  were also identified as independent predictors of falciparum malaria using multivariable logistic regression analysis  in 2003 [P. falciparum. However, it is substantially lower than those reported for schoolchildren from several African countries, including Malawi (60.0%), Kenya (42.0%), Uganda (27.6%), Cameroon (22.8–33.8%) and Tanzania  [P. vivax (0.25%) among schoolchildren in the present study is in line with the low proportion of vivax malaria in Yemen [No published studies have been encountered on falciparum malaria among schoolchildren from Hodeidah governorate in relation to haematological and nutritional indices. This study revealed that 8.0% of almost asymptomatic schoolchildren in Bajil district were infected with  in 2003  and amon in 2003 . It is l in 2003 , 31. It  in 2003 , where ooon 22.8–.8% and T 93/244) . In cont 93/244) , 41. Thein Yemen .P. falciparum can impair the cognitive function of Yemeni children [In Yemen, the prevalence of falciparum malaria has been reduced following the escalated control interventions of the NMCP since its launch in 2000; however, its burden among asymptomatic schoolchildren is high and can pose a threat to malaria control efforts. The asymptomatic nature of most infections in the present study could be attributed to the low-to-moderate parasitaemia levels and the absence of high-level parasitaemia. Asymptomatic cases usually go undiagnosed and untreated, potentially contributing to parasite transmission and the emergence and spread of drug resistance . Gametocchildren . The finchildren , 47, andchildren , 49.The gender, age and residence of schoolchildren were not significant predictors of falciparum malaria in the present study. The lack of significant association between age and malaria is consistent with that found among Tanzanian schoolchildren in a nationwide survey . In contIndependent of other factors, residence near water collections was significantly associated with a 2.6-fold higher risk of falciparum malaria among schoolchildren in Bajil. Similarly, people living near water collections in Hadhramout were at significantly higher risk of malaria . In the Malnutrition represents a major public health problem in countries endemic for malaria. In Yemen, the ongoing complex emergency and humanitarian crisis besides the absence of school feeding programmes aggravate this problem among schoolchildren. The present study revealed malnutrition in more than half of schoolchildren, with stunting and wasting being the most and least prevalent forms of malnutrition, respectively. This shows that chronic malnutrition is more prevalent than acute malnutrition among schoolchildren in the study area. Such predominance of stunting is consistent with those reported from Malawi, Laos and Cameroon , 37, 53 P. falciparum-infected schoolchildren in the present study. It was an independent predictor of falciparum malaria, where anaemic schoolchildren were at approximately six times more likely to have malaria compared to non-anaemic ones. Such a significant association agrees with that among children from Kenya, Malawi and Laos [Regarding the haematological indices and according to WHO’s criteria for the classification of malaria , mild anand Laos , 36, 53,and Laos . Howeverand Laos –59.The mean values of total WBCs and monocytes were significantly lower in infected than non-infected schoolchildren, but within the normal range for both groups. Consequently, it is difficult to establish any clinical implication from such differences in schoolchildren with uncomplicated malaria. Nonetheless, haematological changes are usually common in complicated or severe malaria. Low-to-normal WBC counts are usually observed in malaria patients, mainly due to their localization outside the peripheral circulation rather than actual depletion . In contP. falciparum-infected patients regardless of the exposure frequency or severity of the disease [Thrombocytopaenia can occur in  disease , which c disease . A signi disease , 63.Overall, haematological indices are difficult to use in the prediction of malaria in the study district, even with significant differences between infected and non-infected schoolchildren. In this respect, mild anaemia was the only haematological abnormality observed. This could be partially attributed to the low transmission intensity in the study district compared to the studies in African countries. The impact of transmission intensity on the differences in haematological indices could not be ruled out . The utiThe present study is limited by its cross-sectional design that could not establish a causal relationship between malaria and haematological or nutritional abnormalities. Besides, its findings may not be generalizable to school-age children not enrolled in schools, who may represent a large proportion because of the ongoing complex emergency and humanitarian crisis. Nevertheless, this is the first study to provide essential information about falciparum malaria among schoolchildren in relation to haematological and nutritional indices in one of the largest districts of the most malaria-afflicted governorates in the country. Another limitation is the use of light microscopy for diagnosing malaria among schoolchildren, which overlooks sub-microscopic infections and may underestimate malaria burden in the study setting. Therefore, there is a need for the molecular-based assessment of sub-microscopic reservoir of falciparum malaria, preferably through school-based surveys, in pursuit of the efforts towards malaria elimination. Because the association between severe malaria and haematological and nutritional abnormalities could not be assessed in this school-based study, hospital-based studies are rather needed for this purpose. Longitudinal studies on the development of clinical malaria among schoolchildren with haematological and nutritional abnormalities compared to their normal counterparts are recommended.P. falciparum-infected schoolchildren and is an independent predictor significantly associated with falciparum malaria. Other haematological indices were within the normal range in infected and non-infected schoolchildren and could not be used to predict falciparum malaria. On the other hand, more than half of schoolchildren are malnourished, predominantly being stunted and underweight. However, only underweight is a significant predictor of falciparum malaria. Further studies among children with severe malaria and high parasite densities are recommended.Uncomplicated falciparum malaria is prevalent among 8.0% of schoolchildren in Bajil district of Hodeidah with most infections showing parasite densities lower than 1000 parasites/µL of blood. Residence in proximity to water collections is the only risk factor significantly associated with infection, whereas demographic factors and non-use of vector control tools are not significant predictors of infection among schoolchildren. Mild anaemia is prevalent among half of


Malaria in the United States is rare and most commonly presents among returning travelers from endemic areas. Diagnosis is classically dependent on a positive blood smear or polymerase chain reaction (PCR) test. The objective of this case report is to highlight a case of suspected malaria in a high-risk individual with negative diagnostic testing where a trial of empiric treatment was initiated based on clinical presentation after a thorough discussion of risks and benefits. However, empiric treatment based on a single case is limiting. We present a case of a 56-year-old man with extensive travel history throughout Asia, who presented after multiple episodes of unprovoked 24-hour fevers over the past seven years. A thorough rheumatologic and infectious inpatient workup was negative and oncology was consulted with low suspicion for malignancy. However, based on clinical presentation and history, malaria remained highly suspected and an empiric trial of anti-malarial treatment was initiated. One year after receiving treatment, the patient has not experienced any further febrile episodes. The efficacy of blood smears and PCR may be influenced by the malarial strain, as some species have low circulating biomass. Therefore, blood smears and PCR testing may not always be diagnostic. Clinical signs supportive of a malarial infection include fever, rigors, chills, hepato/splenomegaly, hyperbilirubinemia, and thrombocytopenia. Malaria is endemic to many regions outside of Africa, including Asia, and should be considered in any returning traveler with recurrent fevers. Globally, malaria is a common cause of recurring fevers and is recognized to have high endemicity in sub-Saharan Africa and parts of Asia. However, malaria is also common outside of Africa and presents similarly but has distinct clinical differences. Blood smears with Giemsa stain are the gold standard for diagnosis . HoweverA 56-year-old man presented to the emergency department (ED) after experiencing a fever to 101°F (38.3°C) at home. His past medical history included intermittent febrile episodes over the past seven years and hypertension. His only medication was hydrochlorothiazide.He experienced recurrent unprovoked febrile episodes (occurring every two to three months) for the past seven years. These episodes were acute in onset, without preference for day or night, and followed a stereotypic pattern. They began with chills/rigors followed by high-grade fever, severe day/nighttime diaphoresis, nausea, and sometimes palpitations. Spontaneous resolution typically occurred within 24-48 hours and left him feeling severely fatigued the following day. The highest fever he recorded during an episode was 104.1°F (40.1°C). He denied vomiting, diarrhea, abdominal pain, dysuria, arthralgias, myalgias, or unexpected weight loss in association with these episodes. Between episodes, he felt completely asymptomatic.Five years prior to presentation, the patient resided in China for seven years. He also endorsed travel history to Taiwan, Malaysia, Thailand, Philippines, Korea, Japan, Costa Rica, and the Dominican Republic. He reports taking appropriate preventive measures against mosquitoes such as barriers and chemical prophylaxis while traveling. His first febrile episode occurred in Taiwan within the seven-year period when he was residing in China. Initially, after returning from China, he experienced dyspnea and chest pain with a negative cardiac and pulmonary workup.He did not endorse any illicit drug use, tobacco use, and seldomly consumed alcohol. He was up to date with his preventive health screening exams. Family history was significant for rheumatoid arthritis in his sister. There was no other history of autoimmune disease or familial fever syndromes in his family.Plasmodium vivax (P. vivax) and Plasmodium ovale ) and brucellosis due to his travel history, although there lacked typical periodicity. They noted that splenomegaly, anemia, thrombocytopenia, and mild transaminitis seemed consistent with malaria. A malaria expert was consulted at the Centers for Disease Control and recommended empiric treatment for malaria based on the patient’s history and clinical findings. Following a negative glucose-6-phosphate dehydrogenase (G6PD) deficiency screen, the patient was started on empiric treatment with oral atovaquone/proguanil 1000/400 mg for three days and primaquine 30 mg daily for 14 days.The patient was admitted for systemic inflammatory response syndrome (SIRS) and for a diagnostic assessment for fever of unknown origin. Diagnostic labs and imaging are summarized in Table Three weeks following discharge, the patient was seen for outpatient follow-up. The anemia was resolving with a hemoglobin of 13.3 g/dL; thrombocytopenia fully resolved with a platelet count of 169 B/L. Mild transaminitis persisted (aspartate aminotransferase (AST) 42 IU/L, alanine aminotransferase (ALT) 64 IU/L), total bilirubin had returned to normal (0.7 mg/dL), and alkaline phosphatase(ALP) remained normal at 58 IU/L. Though the improvement in labs may have simply reflected the resolution of SIRS, the patient reported no additional fevers during a telehealth follow-up one year later.The most common causes of recurrent febrile episodes include infectious, rheumatologic, and oncologic etiologies. Oncology did not suspect malignancy as the febrile episodes were too far inconsistent, complete blood cell count (CBC) and smear were normal, and the patient was up to date on cancer screening without a high-risk family history. Rheumatology had low suspicion for an autoinflammatory disorder as the patient had a lack of arthralgias and rash, was completely asymptomatic between episodes, and workup for common autoimmune disorders were negative. Finally, workup for common infectious etiologies including viral, bacterial, and parasitic were negative. Despite this, based on the patient's travel history and clinical presentation, malaria was still highly suspected .Plasmodium falciparum  is the most common, accounting for 99% of known malaria cases, and generally is geographically-limited to sub-Saharan Africa [P. vivax is the most common species outside of Africa and accounts for 50% of non-African cases in the Americas, Eastern Mediterranean region, and Asia [P. vivax has been reported to be as high as 80% of the total global burden [Plasmodium knowlesi,P. ovale, and Plasmodium malariae [There are five Plasmodium species known to infect humans: falciparum, malariae, ovale, vivax, and knowlesi . Plasmodn Africa ,5. P. viand Asia ,5. In Asl burden . Other smalariae ,6.P. vivax is confirmed to have a latent state in the liver (hypnozoites) with the ability to remain dormant for up to two years after primary infection [P. ovale is suspected to have a hypnozoite stage as well, however, the evidence for this is limited and controversial [P. vivax and P. ovale have reported relapse periods consistent with our patient’s presentation, however, P. ovale less commonly produces clinical malaria and is more common in Africa than Asia [P. vivax is not commonly seen in Africa due to the lack of the Duffy antigen on erythrocytes in the region [Due to the infrequency of febrile episodes in this case, a Plasmodium species capable of producing hypnozoites seems most likely. Only nfection . P. ovaloversial . Both P.han Asia ,7. P. vie region .P. vivax infection begins with a prodrome of headache, anorexia, malaise, myalgias, and gastrointestinal symptoms for one or more days followed by a remitting fever [P. falciparum, P. vivax induces an inflammatory response at a significantly lower parasite load [P. vivax has a predilection for reticulocytes, ultimately infecting < 2% of circulating erythrocytes while maintaining a greater capacity of causing severe anemia than P. falciparum [P. vivax [The classic episode of ng fever . Subsequng fever . These eng fever . In compite load . AdditioClinical signs and abnormalitiesP. falciparum is well known to cause adherence of infected RBCs to the endothelium, causing damage and activation, and subsequently elevating D-dimer levels [P. vivax is reported to have the same effect albeit with a 10-fold lower capacity. D-dimer levels in-turn reflect these pathophysiological differences [D-dimer is often elevated during malarial infections . P. falcr levels . P. vivaferences .P. falciparum than P. vivax infections, suggesting that the etiology is more likely related to falciparum-specific etiologies (e.g. increased RBC cytoadherence) and not the presence of hepatic hypnozoites in P. vivax [In our case, our patient had a mild transaminitis and mild hyperbilirubinemia. Severe malarial infections can cause “malarial hepatopathy” which are defined by severe elevations of liver function tests . These sP. vivax ,10. Our P. vivax .On CT, our patient was found to have mild pulmonary edema and free peritoneal fluid. These findings are rarely reported in non-severe malarial infections and consistent with the effects that malaria exerts on endothelium and microvascular function ,12.Thrombocytopenia commonly occurs in malaria as well. The exact mechanism is not completely understood but centers around immunologic mechanisms damaging thrombocytes and causing excess platelet removal . ThromboDiagnostic studiesP. falciparum than P. vivax due to P. vivax having a preference for infecting pre-circulating reticulocytes [Analysis of thick smear blood samples under light microscopy has greater sensitivity for diagnosing ulocytes ,15. Seroulocytes . Antigenulocytes . Overallulocytes . We idenulocytes . In settulocytes ,20. Negaulocytes ,20. A prulocytes . From thP. falciparum. This means that artemisinin-based combination therapies should be primarily utilized, mainly for its ability to overcomes chloroquine-resistance. If the patient has G6PD, treatment should be centered around primaquine. Additional treatment with primaquine for 14 days in all transmission settings should be performed to prevent relapse [When the malaria species is unknown, the World Health Organization recommends treatment under the assumed diagnosis of uncomplicated malaria by P. vivax as the predominating, causative species. PCR is the best test when suspicious for P. vivax, however, it is not always diagnostic. Recurrence of febrile episodes maybe months to years apart. Clinical signs supportive of a malarial infection are fever, rigors, chills, hepato/splenomegaly, hyperbilirubinemia, and thrombocytopenia. Severe manifestations of malaria are life-threatening. G6PD should be tested for prior to empiric treatment. When the malarial organism is unknown, treatment is approached as if the patient has an uncomplicated P. falciparum infection.Malaria is common and endemic to many countries outside of Africa (e.g. Asia), with