Plasmodium falciparum during a randomised controlled trial.Naturally acquired malaria immunity has many determinants and, in the absence of immunological markers of protection, studies assessing malaria incidence through clinical endpoints remain an approach to defining immunity acquisition. We investigated the role of age in disease incidence and the effects of chemoprophylaxis on clinical immunity development to A total of 415 Tanzanian infants were randomly assigned to receive weekly malaria prophylaxis with Deltaprim (3.125 mg of pyrimethamine plus 25 mg of dapsone) or placebo between the ages of 2 and 12 mo. Children were followed up until 4 y of age. Uncomplicated febrile malaria, severe malaria, and anaemia morbidity were assessed through hospital-based passive surveillance. Compared with the group of control participants, there was a marked reduction in the incidence of clinical malaria, severe malaria, and anaemia in the group of children who had received chemoprophylaxis during the first year of life. After discontinuing the intervention, there was a significant increase in the incidence of clinical malaria for 2 y. The cumulative rates of clinical malaria, by age 4 y, were slightly higher in the group of children who had previously received chemoprophylaxis: 3.22 episodes versus 3.02 episodes in the group of control participants; rate difference 0.20 . By age 4 y, the cumulative rates of severe malaria, however, were slightly lower in chemosuppressed children (0.47 versus 0.59) (rate difference −0.12 [95% CI: −0.27 to 0.03]). The number of episodes of anaemia was also slightly lower in chemosuppressed children by age 4y: 0.93 episodes (95% CI: 0.79 to 0.97) versus 1.12 episodes in the group of control participants (95% CI: 0.97 to 1.28) (rate difference −0.19 [95% CI: −0.40 to 0.01]), respectively.P. falciparum antigens through chemoprophylaxis early in life can delay immunity acquisition. Infants appear to acquire immunity faster than older children, but have a higher risk of developing severe forms of malaria and anaemia. These findings provide insight on the interplay between immunity and exposure-reduction interventions.Reducing exposure to  John Aponte and colleagues report that reducing exposure to parasite antigens early in life through chemoprophylaxis, while reducing the incidence of severe malaria, can delay the development of immunity. Plasmodium falciparum, a parasite that is transmitted from person to person by infected mosquitoes. People living in areas where malaria is common  gradually acquire immunity to this parasite through repeated exposure to it, but the development of this immunity is complex. As with other infectious diseases, the immune system has to learn how to recognize and attack the parasite so that parasitaemia (the number of parasites in the blood) is kept to a minimum. In addition, because several symptoms of clinical malaria  are side effects of the immune system's response to the parasite, it also has to learn not to overreact to this foreign invader. Consequently, in malaria-endemic areas, where individuals first become infected with P. falciparum as infants, many children develop severe malaria and anemia (parasite-induced killing of red blood cells) during their first 5 y of life. Later, as their immunity to P. falciparum develops, they experience less severe disease and reduced parasitaemia.Malaria is a life-threatening disease caused by P. falciparum is acquired or how age affects this process. This study was done to document the long-term effects of malaria prophylaxis given to young Tanzanian infants. More specifically, the researchers examined whether and how prophylaxis affects the rate of acquisition of malaria immunity, and whether a possible delay in immunity would be associated with more severe forms of malaria in children.Little is known about how quickly immunity to Infants in Ifakara, a town in Tanzania, received either antimalarial tablets or placebo (inactive) tablets every week between the ages of 2 and 12 mo. Cases of clinical malaria (parasitaemia and fever), severe malaria , and anemia among the children were recorded until they were 4 y old. During their first year, the children receiving antimalarial drugs had fewer episodes of malaria, severe malaria, and anemia than the children receiving the placebo. After the antimalarial drugs were stopped, cases of clinical malaria, severe malaria, and anemia were more frequent among the treated children than among the control children for the next 2 y. By the time they were 4 y old, the treated children had had slightly more episodes of clinical malaria in total than the control children, but slightly fewer episodes of severe malaria and anemia.P. falciparum in early life with continuous malaria prophylaxis delays the acquisition of immunity to the parasite. They also show that infants acquire this immunity slightly faster than do older children, but that this speedier acquisition of immunity is accompanied by a slightly increased risk of severe malaria and anemia. Because these findings may, in part, reflect a local decrease in malaria transmission that occurred during the study, they need confirming in other settings and with many more children. Nevertheless, they suggest that although age at first exposure to P. falciparum helps to determine both the rate at which immunity is acquired and the severity of disease caused by the parasite, delaying the acquisition of immunity through early prophylaxis is unlikely to have long-term negative health effects. This information will help public-health experts to plan prophylactic interventions designed to control malaria transmission in endemic regions.These findings show that reducing exposure to http://dx.doi.org/10.1371/journal.pmed.0040242.Please access these Web sites via the online version of this summary at malaria and on immune responses to malaria (in English and Spanish)US Centers for Disease Control and Prevention information on MedlinePlus encyclopedia page on malaria (in English and Spanish)malaria Information from the World Health Organization on immunity to malaria and on malaria and the human immune systemShort articles from the Wellcome Trust on  Plasmodium falciparum infection and disease  as well as control participants) at recruitment allowed their identification during all contact with the project personnel. A system of bi-monthly demographic surveillance provided information on vital events not registered at the hospital. Malaria smears were prepared for all inpatients and for out-patients when there was fever, history of fever, or pallor.http://www.hawksley.co.uk/).Thick blood films were stained with Giemsa and read on a light microscope following standard quality-control procedures . The PCVP. falciparum parasitaemia of any density at any contact with the health services. Severe anaemia was defined as a PCV of less than 25% at any contact with the health services. Severe malaria was defined as the presence of parasitaemia together with any of the following risk factors: dehydration, respiratory distress, impaired consciousness, and hypoglycaemia. These factors were selected because they had been previously shown to be independently associated with death for children in the study setting [Clinical malaria was defined as an episode of fever (axillary temperature >37.5 °C) plus The effect of chemoprophylaxis on the risk of clinical malaria and anaemia changes with age, and is different before and after the period of chemoprophylaxis. Thus, in order to produce smooth estimates of the effect of chemoprophylaxis with age, we modelled the incidence of clinical malaria, severe anaemia, and other outcomes using Poisson regression models of small time intervals, and imposing Bayesian autoregressive constraints. This type of model allows the effect of chemoprophylaxis to change with time but, for any given time period, the effect should be similar to the effect in the previous period of time. Details of the models are presented in http://www.stata.com/) software. For the Bayesian models, we present the mean posterior value and the 95% CIs. Bayesian models were fitted using WinBugs 1.4 [In order to compare the occurrence of malaria, anaemia, or other outcomes, we calculated the cumulative rate (CR) as the area under the curve for the estimated monthly incidence in each treatment group. The CR at any given age could be interpreted as the expected number of episodes that a child experiences up to that age. Details of the CR estimation are presented in Bugs 1.4  and the Bugs 1.4 .The trial profile for the intervention and corresponding cohort of control participants is shown in Children in the placebo group had, on average, 3.3 hospital admissions during the first 4 y of life (95% CI: 3.03 to 3.60), compared to 3.1 admissions (95% CI: 2.83 to 3.37) for children who had received chemoprophylaxis during the first year. The admission rate was highest in infants and decreased sharply with age (incidence rate of 1.25 admissions/PYAR).P. falciparum infections at different ages. A major strength of this study was that, although transmission intensity varied over the course of follow-up, both cohorts were similarly exposed to malaria. The incidence of clinical malaria in children receiving placebo fell gradually during the first 4 y of life, reflecting the natural development of immunity to uncomplicated clinical disease. However, the documented rate of immunity acquisition was slower than expected given the moderate-to-high transmission rate that had been estimated in the area. This may be partly explained by the fact that the study population had prompt access to diagnosis and treatment, which may delay the development of immunity [P. falciparum infection [This study investigated the development of clinical immunity against malaria during the first 4 y of life in two contemporaneous cohorts of children experiencing immunity ,19. Nonenfection .Malaria chemoprophylaxis with Deltaprim in children aged between 2 and 12 mo caused a significant decrease in the risk of febrile malaria, anaemia, hospital admission, severe malaria, and all causes of hospital attendance during the first year of life. However, the reduction in these endpoints decreased with increasing age, approaching zero towards the end of the first year of life. The cause of this trend is unknown. Compliance did not decrease, and it is unlikely that drug resistance would develop in such a short timeframe. It is possible that the use of a standard recommended dose during the prophylaxis period, which was unlinked to a dose per weight of the child, resulted in sub-therapeutic drug concentrations in older children. A hypothetical reduction with age in the synergy between declining maternally transferred immunity and a moderately efficacious drug may also contribute to the loss of drug efficacy during the first months of infancy. However, the loss in efficacy was also apparent in the latter months of infancy when transplacentally transferred antibodies are not expected to remain .p = 0.512). There was an increased number of deaths in the chemosuppressed group  in the 2–4 y age group. However, we were unable to obtain information on the causes and circumstances of those deaths. Given that the number of deaths was low, this difference is most likely to be due to chance, although we cannot rule out a potential and transient increased risk in mortality.During the entire follow-up period, the difference in deaths was not statistically significant  . FinallyProtocol S1(85 KB DOC)Click here for additional data file.


Malaria parasites invade human red blood cells, and it had already been recognized in the 1940s that diseases of red blood cells such as thalassemia and sickle-cell anemia, which are the most common group of genetic disorders in humans, are mainly found in populations exposed to malaria and their descendants. It seems that much of the genetic variation that affects the phenotype of red blood cells appears to have evolved due to natural selection by malaria. Susceptibility to malaria is also thought to be determined by genetic variation in the human immune system. We know less about the specific immune system genes involved, but this is an important area of research because researchers hope that understanding the molecular basis of natural immunity will speed up the development of an efficient malaria vaccine.Rather than focusing on the identification of specific genes and gene variants, Margaret J. Mackinnon and colleagues are interested in the relative contributions of host genetics and other factors to the risk of malaria. To estimate the overall contribution of genetic factors to the difference in disease incidence between individuals within a population, one needs three types of data: (1) disease incidence for individuals over a certain period of time , (2) information on genetic relatedness of the individuals in the population, and (3) a setup in which individuals with different levels of relatedness share the same environment and/or where related individuals live in different environments.  Mackinnon and colleagues studied two populations of children from a malaria-endemic area in Kenya for which they could obtain the necessary data. In one case, they determined incidence of mild clinical malaria in 640 children over a period of five years. Genetic relatedness between the children was determined by verbal interviews with their mothers. A typical household  consisted of a group of three to six adjacent houses. Within each household, the children formed several full-sibling, half-sibling, and first-cousin groups. The second study monitored severe malaria that led to hospitalization and nonmalaria hospitalizations in 2,900 children, also over a five-year period. This analysis concentrated on full-siblings.Using a standard statistical genetics method of relating similarity in phenotype to similarity in genotype, they found that host genetic factors accounted for approximately one-quarter to one-third of the total variation in susceptibility in the populations to malaria. Of this percentage, only a small proportion could be attributed to the best known malaria resistance genes. This is consistent with other studies that suggest that malaria susceptibility is under the control of many different genes, with each individual gene having a relatively small epidemiological effect.When assessing the contribution of household factors, the researchers found that for mild clinical malaria, those factors accounted for slightly more than a quarter of the total variation. For hospitalized malaria, they contributed about 15%, and for hospitalizations with fever that turned out not to be malaria, they contributed approximately 35%. Overall, children living in the 10% of households with the highest malaria incidence had approximately twice as many infections per year than those living in the 10% of households with the lowest incidence.The researchers do not question the long-term benefits of understanding the genetic factors but conclude that “identifying and tackling the household effects must be the more efficient route to reducing the burden of disease in malaria-endemic areas.” Factors such as suitable conditions for mosquitoes to breed and survive as well as human behavior are likely to play major roles. “We need to determine what makes the difference between low-risk and high-risk households,” Mackinnon says, “but whatever it is, it seems likely to be an easy target using tools such as education and the low-cost, low-tech devices that we already have at hand such as bed nets, residual indoor spraying, and cleaning up backyards for mosquito breeding sites.”


Presumptive treatment of malaria in febrile children is widely advocated in Africa. This may occur in the absence of diagnostic testing or even when diagnostic testing is performed but fails to detect malaria parasites. Such over-treatment of malaria has been tolerated in the era of inexpensive and safe monotherapy. However, with the introduction of new artemisinin-based combination therapy (ACT), presumptive treatment becomes economically and clinically less acceptable.The risks and benefits of only treating children with microscopy confirmed malaria using a prospective cohort design were investigated. A representative sample of 601 children between one and 10 years of age were recruited from a census population in Kampala, Uganda and were followed for all of their health care needs in a study clinic. Standard microscopy was performed each time a child presented with a new episode of fever and antimalarial therapy given only if the blood smear was positive.Of 5,895 visits for new medical problems 40% were for febrile illnesses. Of the 2,359 episodes of new febrile illnesses, blood smears were initially reported as negative in 1,608 (68%) and no antimalarial therapy was given. Six of these initially negative smears were reported to be positive following quality control reading of all blood smears: four of these patients were subsequently diagnosed with uncomplicated malaria and two cleared their parasites without antimalarial treatment. Of the 1,602 new febrile illnesses in which the final blood smear reading was classified as negative, only 13 episodes (0.8%) were diagnosed with malaria in the subsequent 7 days. All 13 of these episodes of malaria were uncomplicated and were successfully treated.In this urban setting, malaria was responsible for only 32% of febrile episodes. Withholding antimalarial therapy in febrile children with negative blood smears was safe and saved over 1,600 antimalarial treatments in 601 children over an 18-month period. In the era of expensive ACT, directing resources towards improving diagnostic and treatment practices may provide a cost-effective measure for promoting rational use of antimalarial therapy. The practice of presumptive treatment of malaria has been widely advocated in sub-Saharan Africa as a means of increasing antimalarial coverage and reducing the risk of progression to severe disease and death. However, it is well known that such practice frequently results in the unnecessary use of antimalarials, especially in lower transmission settings and older patient populations ,2. Such Microscopy remains the gold standard for laboratory confirmation of malaria and its use could provide an efficient and cost effective means of significantly reducing the number of unnecessary antimalarial treatments . HoweverThis study was conducted in Kampala, the capital of Uganda, with an estimated population of 1.2 million. Malaria is meso-endemic in this area  , occurriParticipants were followed up at a designated study clinic located in the outpatient department of Mulago Hospital, the primary referral hospital in Uganda. Parents/guardians were asked to bring their child to the study clinic for all of their medical care. The study clinic was open daily from 8:00 am to 5:00 pm and after-hours care was available at Mulago Hospital.Children who presented to the study clinic with new medical problems underwent a standardized medical evaluation. Subjects who were febrile (tympanic temperature ≥ 38.0°C) or reported history of fever in the previous 24 hours had blood obtained by fingerprick for a thick blood smear. If the thick blood smear was positive, the patient was diagnosed with malaria regardless of the parasite density. Patients with uncomplicated malaria were given directly observed therapy with one of three combination antimalarial regimens under evaluation. Patients with severe malaria  or dangeStudy participants were encouraged to visit the Mulago Hospital pediatric emergency department when urgent care was needed outside of study clinic hours. Participants were instructed to inform emergency department personnel of their involvement in the study at the time of registration and to visit the study clinic on the following day. Identified Mulago Hospital personnel were educated about the study protocol and a nurse, employed by the project, oversaw adherence to the study protocol.Children were evaluated for routine assessment if approximately 30 days elapsed without having a blood smear obtained. These routine assessments were made to ensure compliance with the study protocol and obtain blood smears for the evaluation of asymptomatic parasitaemia.Thick blood smears were stained with 2% Giemsa for 30 minutes. Parasite density was estimated by counting the number of asexual parasites per 200 white blood cells and calculating parasites per μL, assuming a white blood cell count of 8,000 cells per μL. A smear was judged to be negative if no parasites were seen after review of 100 high powered fields. The diagnosis and management of malaria was based on initial readings of blood smears. Final microscopy results were based on a rigorous quality control system which included a second microscopist re-reading all blood smears and any discrepancies between the first and second readings resolved by a third microscopist.Written informed consent was obtained from the parents/guardians of children for their participation in the study. Ethical approval was obtained from the Uganda National Council of Science and Technology, the Makerere University Research and Ethics Committee, and the University of California, San Francisco Institutional Review Board.Data were double-entered in Access  and statistical analysis was performed using Stata version 8 . Categorical variables were compared using the chi-square test. A p-value of < 0.05 was considered statistically significant.A detailed description of the baseline characteristics of the 601 children enrolled in the cohort have been published . BrieflyA total of 77 children were prematurely excluded from the study for the following reasons; movement out of Kampala for > 60 days (n = 49), inability to locate child for > 60 consecutive days (n = 12), withdrawal of consent (n = 11), and diagnosis of serious chronic disease requiring frequent medical care (n = 5). Follow-up for the remaining 524 patients continued until May-June 2006, at which time ITNs were distributed to the entire cohort. The cumulative follow-up period for the cohort was 740 person years, which constituted 93% of the potential follow-up time.A total of 5,895 visits were made to the study clinic for new medical problems. Among all visits for new medical problems, 2,359 (40%) were for febrile illnesses (tympanic temperature ≥ 38.0°C and/or subjective fever in the previous 24 hours) Figure . A totalOf the 2,359 episodes of new febrile illnesses, 751 (32%) were associated with an initial positive blood smear, and the participants were diagnosed and treated for malaria .


Anaemia is a major cause of morbidity and mortality for children in Africa. The plasma protein haptoglobin (Hp) binds avidly to free haemoglobin released following malaria-induced haemolysis. Haptoglobin polymorphisms result in proteins with altered haemoglobin-binding capacity and different antioxidant, iron-recycling, and immune functions. Previous studies examined the importance of haptoglobin polymorphism in malaria and iron homeostasis, but it is unknown whether haptoglobin genotype might be a risk factor for anaemia in children in a malaria-endemic area.p = 0.0009, coefficient = −4.2). Iron status was not influenced by haptoglobin genotype.A cohort of 780 rural Gambian children aged 2–6 y was surveyed at the start and end of the malaria season. Samples were taken to assess haemoglobin (Hb) concentration, iron status , haptoglobin concentration, α-1-antichymotrypsin (a measure of inflammation), and malaria parasites on blood film. We extracted DNA and genotyped for haptoglobin, sickle cell, and glucose-6-phosphate (G6PD) deficiency. Mean Hb levels fell over the malaria season. Children with the haptoglobin 2-2 genotype (17%) had a greater mean drop in Hb level over the malaria season  compared to other children . In multivariate regression analysis, controlling for baseline Hb level, age group, village, malaria parasites on blood film, iron status, haptoglobin concentration, and G6PD deficiency, haptoglobin genotype predicted Hb level at the end of the malaria season (p = 0.0009) was comparable to that of G6PD deficiency or HbAS .The finding that haptoglobin 2-2 genotype is a risk factor for anaemia in children in a malaria-endemic area may reflect the reduced ability of the Hp2-2 polymer to scavenge free haemoglobin-iron following malaria-induced haemolysis. The magnitude of the effect of haptoglobin genotype (4 g/l Hb difference, Haptoglobin 2-2 genotype seems to be a risk factor for anaemia in children in a malaria-endemic area, possibly reflecting the reduced ability of the Hp2-2 polymer to scavenge free haemoglobin-iron following malaria-induced haemolysis. The1Hp and2Hp alleles are encoded by a single gene on Chromosome 16; the2Hp allele was formed from an intragenic duplication originating from a nonhomologous crossing-over of two1Hp alleles [Anaemia (haemoglobin [Hb] < 110 g/l) is a serious public health problem affecting more than half of children less than 5 y of age in malaria-endemic countries of Africa; in a survey in The Gambia 76% of children were anaemic . In sub-alleles . HaptoglThe Hp2-2 polymer has very different biochemical and biophysical properties compared to Hp1-1 and Hp1-2 . The Hp2The pathogenesis of malarial anaemia is complex and includes haemolysis, accelerated erythrophagocytosis, and cytokine-induced dyserythropoiesis ,12; red2Hp allele would have a lower haemoglobin level after the malaria season. To control for the multifactorial aetiology of anaemia we measured baseline haemoglobin levels in the same children prior to the malaria season, and other factors that might influence haemoglobin level. We explored the interaction with plasma iron markers and compared the impact of haptoglobin with other genetic polymorphisms that might influence haemoglobin levels over the malaria season; namely, HbS and the G6PD A and A− variants common to sub-Saharan Africa  × 100). We also measured αGenotyping (as opposed to the commonly used electrophoretic phenotyping) allowed haptoglobin typing of patients regardless of possible hypohaptoglobinaemia secondary to subclinical malaria. DNA was extracted from peripheral blood leucocytes according to standard methods  and quanAnalyses were conducted using STATA version 8.0 . Pearson's Chi-square test assessed associations between haptoglobin genotype and other genetic polymorphisms, and binomial regression was used to test for differences in allele frequency between villages. Normality diagnostics were performed and continuous variables that were not normally distributed were log-transformed. Weight for height Z-scores were calculated using Epi Info 2000 software. Prior functional data suggested the Hp2-2 phenotype had unique properties compared to the Hp1-2 or Hp1-1 phenotypes ,10. Thi1-antichymotrypsin, haptoglobin concentration, G6PD deficiency, and HbS) and retained ifp < 0.1. Haptoglobin genotype was added last. The validity of the assumptions of normality and constant variance were confirmed with residual plots.The effect of haptoglobin and other genotypes on the drop in haemoglobin was first assessed by Student's t-test. Further analysis, using stepwise multivariate linear regression, controlled for other variables likely to influence haemoglobin level at the end of the malaria season. Here, rather than normalising haemoglobin values by calculating the drop during the malaria season, baseline haemoglobin value was used as an explanatory variable in the model. Age group, malaria parasites (on blood film), village, and baseline haemoglobin level were first included in the model. Other variables were added manually  to 101.2 g/l  by the end of the malaria season; a mean drop of 5.8 g/l  (p = 0.0001). In primary analysis, children carrying the2/2Hp genotype had a mean drop in haemoglobin of 8.9 g/l  compared with 5.1 g/l  for the other genotypes (p = 0.02 by Student's t-test). The drop in haemoglobin was similar for the1/1Hp and1/2Hp genotypes (5.9 g/l and 4.6 g/l respectively). In secondary analysis an ANOVA for the three genotypes also indicated a greater drop in mean haemoglobin level in children with the2/2Hp genotype (p = 0.045). By comparison, sickle genotype and G6PD deficiency did not significantly influence drop in haemoglobin level over the malaria season. Drop in haemoglobin level over the malaria season for haptoglobin, HbAS, and G6PD A type deficiency is shown in2/2Hp genotype . As found previously [2/2Hp genotype had lower mean haptoglobin concentrations. We also found an increased number of asymptomatic children with malaria parasitaemia in the2/2Hp group at the end of the malaria season .Overall, mean haemoglobin levels fell across the malaria season; from 106.9 g/l  emerged as significant predictors of haemoglobin level at the end of the malaria season . A further multivariate analysis with change in Hb as the dependent variable found a similar effect for haptoglobin genotype . Iron status  strongly influenced haemoglobin level, but was not significantly altered by haptoglobin genotype.Multiple factors influenced haemoglobin level. A multivariate regression analysis was performed with haemoglobin level at the end of the malaria season as dependent variable. In this model, baseline haemoglobin level, village, age group, malaria parasites on blood film, iron status, haptoglobin concentration (a measure of haemolysis in the last 10 d), G6PD A type deficiency, and haptoglobin genotype . Baseline haemoglobin levels were similar by Hp genotype, but by the end of the malaria season differed significantly in the2/2Hp genotype (17% of children) compared to the1/1Hp and1/2Hp genotypes . The effect of2/2Hp was greater than that of previously described genetic variants such as G6PD A type deficiency  and HbAS . The difference by haptoglobin genotype was robust to adjustments for other factors influencing haemoglobin level and is also supported by our retrospective analysis of a cross-sectional study of haptoglobin phenotypes conducted in this population in the 1970s [p = 0.028,n = 825). A study from Melanesia has also reported similar differences in the 0- to 4-y age group in a malaria-endemic area  [Multiple factors contributed to the complex aetiology of anaemia in young rural Gambian children; both iron status and malaria infection emerged as strong predictors of haemoglobin level. We speculated that haptoglobin, encoded by a gene that regulates haemoglobin-iron metabolism after haemolysis, might critically influence haemoglobin levels in an environment of malaria-induced haemolytic stress and iron deficiency. Haemoglobin levels fell generally over the malaria season, but this effect was concentrated in children carrying thee 1970s . This fon = 41) .2/2Hp genotype result in anaemia under conditions of malaria-induced haemolysis and iron deficiency? We propose three possible explanations for impaired haematological recovery from malaria infection in the2/2Hp genotype. These mechanisms need not be mutually exclusive.So how might the2/2Hp genotype due to delocalisation of iron into poorly exchangeable macrophage storage compartments may result in iron-deficient erythropoiesis. The haemoglobin-scavenging macrophage receptor CD163 has greater functional affinity for the Hp2-2-haemoglobin complex compared to the Hp1-1-Hb complex [2/2Hp genotype is associated with iron loading [Firstly, impaired iron recycling in thecomplex  resultincomplex . We therloading ,32, andloading –35. Fur2/2Hp genotype may influence haematological status by failing to quench haemoglobin-iron-mediated oxidant stress. In vitro work found that the Hp 2-2 protein was associated with reduced inhibition of oxidation of low-density lipoprotein (LDL), increased redox active iron and increased oxidant stress levels compared to the Hp1-1 protein [Secondly, theprotein ,37. Theprotein ,38, redprotein , and sigprotein . Malariaprotein  and incrprotein . Moreoveprotein ,43.2/2Hp genotype, is also associated with a reduced respiratory burst and decreased nitric oxide, IFNγ, and TNF production [A third possibility is modulation of inflammatory cytokine balance. Haptoglobin promotes Th1 over Th2 activation in mice experiments  and suppduction . The sig2Hp allele is thought to have spread under strong genetic pressure, and haptoglobin disease associations are reviewed in Langlois and Delanghe (1996) [2/2Hp genotype, present in 17% of children in our study, is also common. Whether there is an association between haptoglobin polymorphisms and susceptibility to malaria infection remains controversial; studies indicate either a protective or neutral effect of2/2Hp genotype [2/2Hp genotype at the end of the malaria season (p = 0.02 for2/2Hp versus1/2Hp and1/1Hp combined). A further possibility is that the2/2Hp genotype might be associated with asymptomatic, chronic parasitaemia that contributes to anaemia, but may also provide protection against severe malaria.The (1996) . The str (1996) . Furtherenotype . We foun2/2Hp genotype is a risk factor for childhood anaemia in malaria-endemic countries. The high prevalence of a potentially detrimental allele might be explained by balancing selection pressures. An intriguing possibility is that the2/2Hp genotype may protect against life-threatening malaria [In summary, our results suggest that themalaria ,19 at tTable S1(23 KB DOC)Click here for additional data file.Table S2(38 KB DOC)Click here for additional data file.Table S3(33 KB DOC)Click here for additional data file.http://vega.sanger.ac.uk/index.html) gene identification numbers are OTTHUMG00000073117 for HP and OTTHUMG00000024237 for G6PD. The dbSNP (build 125) reference number for the polymorphism for sickle-cell anaemia (HbS) is rs334.The Vega Nucleotide Sequence Database (Anaemia is very common in African children. There are many different causes of the anaemia, including infections with malaria, worms, and other parasites. Anaemia is particularly important in children, as it can affect how well they participate at school, as well as how they recover from other illnesses.There is a protein called haptoglobin whose job it is to pick up and help remove from the body the haemoglobin that is released from red cells when they die, either naturally or after infections such as malaria. This protein exists in two forms, 1 or 2; the possible combinations of the protein are 1–1, 1–2, or 2–2. 2–2 is the least efficient at binding to the free haemoglobin. Previous work has suggested that the haptoglobin type people carry may affect how they respond to malaria, and whether they become iron deficient. However, it is not known whether the haptoglobin type of children will affect their risk of being anaemic in areas where malaria is very common.A total of 780 rural Gambian children between 2 and 6 years of age were examined at the start and end of the malaria season. The authors found that average haemoglobin levels fell over the malaria season, and children who had the haptoglobin 2–2 type had the greatest drop compared to other children. When the authors looked at a number of other factors, including the children's age, haemoglobin at the start of the season, and which village they were from, the haptoglobin type still predicted whether haemoglobin levels would fall at the end of the malaria season.These findings suggest that the haptoglobin type a child has may have be an important influence on whether that child gets anaemia in areas where malaria is very common. It is not clear why this haptoglobin type is frequent in this population if it has an adverse effect on haemoglobin levels; one possibility is that the 2–2 type may protect against life-threatening malaria. Further research needs to be done to check this finding and to investigate exactly the potential mechanisms of anaemia.The World Health Organization has a page of information on anaemia:http://www.who.int/topics/anaemia/enMedline Plus has a page of links to malaria:http://www.nlm.nih.gov/medlineplus/malaria.htmland an explanation of what haptoglobin is:http://www.nlm.nih.gov/medlineplus/ency/article/003634.htm


Novel antimalarial drug targets are urgently needed to reduce global morbidity and mortality. Our prior results suggested that inhibiting erythrocyte Gs as a novel antimalarial target. Erythrocyte “ghosts” loaded with a Gs peptide designed to block Gs interaction with its receptors, were blocked in β-adrenergic agonist-induced signaling. This finding directly demonstrates that erythrocyte Gs is functional and that propranolol, an antagonist of G protein–coupled β-adrenergic receptors, dampens Gs activity in erythrocytes. We subsequently used the ghost system to directly link inhibition of host Gs to parasite entry. In addition, we discovered that ghosts loaded with the peptide were inhibited in intracellular parasite maturation. Propranolol also inhibited blood-stage parasite growth, as did other β2-antagonists. β-blocker growth inhibition appeared to be due to delay in the terminal schizont stage. When used in combination with existing antimalarials in cell culture, propranolol reduced the 50% and 90% inhibitory concentrations for existing drugs against P. falciparum by 5- to 10-fold and was also effective in reducing drug dose in animal models of infection.We investigated the erythrocyte guanine nucleotide regulatory protein Gs antagonism offers a novel strategy to fight infection and that it has potential to be used to develop combination therapies with existing antimalarials.Together these data establish that, in addition to invasion, erythrocyte G protein signaling is needed for intracellular parasite proliferation and thus may present a novel antimalarial target. The results provide proof of the concept that erythrocyte G Erythrocyte G protein signaling is needed for intracellular malarial parasite proliferation and thus may present a novel antimalarial target. New drugs for treatment of malaria are urgently needed, because the malaria parasite has evolved resistance against virtually all types of commonly used drugs. When a person is bitten by a malaria-infected mosquito, the parasite first infects the person's liver cells before going on to infect red blood cells, where the parasites multiply and develop into a parasite stage called a schizont. The red blood cells then burst and release more schizonts into the bloodstream; it is this “blood stage” of infection in humans that causes the symptoms of disease. Therefore efforts to develop new drugs against malaria often focus on this “blood stage” of infection. One strategy for developing new drugs is termed the “host-targeted” approach. This means that rather than trying to block processes occurring within the parasite itself, a drug can be developed which blocks processes within the person's red blood cells, and which would otherwise be needed for the parasite to complete its life cycle. It will be difficult for malaria parasites to evolve resistance to such a drug, because changes in a person's red blood cells occur much more slowly than in the parasites themselves.2-adrenergic receptor (β2-AR) and heterotrimeric G protein (Gs). These two proteins act together to pass messages across the surface of the membrane to inside the cell. Small molecules could be used to block signaling through β2-AR and Gs, and therefore potentially to provide a new way of preventing malaria parasites from entering red blood cells and multiplying within them.This research group has been studying a set of molecular processes within human red blood cells which seemed to be required for entry of malaria parasites into the cells. They wanted to get a better understanding of those processes and, specifically, to find out whether it would be possible to use particular molecules to block those processes, and by doing so to prevent malaria parasites from entering and multiplying within red blood cells. In particular, when the malaria parasites invade the red blood cell, they form membranes around the red blood cell, containing lipids and proteins “hijacked” from the red blood cell membrane. These researchers already knew that two particular proteins were hijacked in this way; the βs signaling within the ghosts. This peptide also prevented malaria parasites from developing inside the ghosts. Therefore, they concluded that Gs signaling inside the red blood cell was important for the parasite life cycle. The researchers then examined a drug called propranolol which is already known to act on Gs signaling and which is commonly prescribed for high blood pressure. This drug also blocked development of malaria parasites inside the ghosts when used at a particular concentration. Finally, the researchers studied the effect of giving propranolol, along with other antimalarial drugs, to human malaria parasites in a culture dish and to mice injected with a malaria parasite that infects rodents. In these experiments, adding propranolol reduced the amount of other “parasite-targeted” drugs that were needed to effectively treat malarial infection in tissue culture and in mice.Firstly, the researchers made red blood cell “ghosts” in which to study these molecular processes. This meant that they took fresh red blood cells from healthy human volunteers, burst them to remove half the contents and loaded them with markers and other cargoes before resealing the membranes of the cell. These resealed markers and cargoes allowed them to see what was happening inside the cells. Malaria parasites were able to invade these ghosts normally and multiply within them. When the researchers introduced a specific peptide (a molecule consisting of a short series of amino acids), they found that it blocked Gs signaling pathway is important for the malaria parasite's life cycle opens up new possibilities for drug development. Specifically, propranolol  might itself provide a new candidate therapy, either alone or in combination with existing drugs. These combinations would first, however, need to be tested in human clinical trials, perhaps by seeing whether they have antimalarial activity in people who have not responded to existing antimalarial drugs. Since it acts to lower blood pressure, which can already be low in some people with malaria, there are some concerns that propranolol might not be a suitable drug candidate for use, especially with existing antimalarial drugs that also reduce blood pressure. However, other molecules which block Gs signaling could be tested for activity against malaria should propranolol prove not to be an ideal drug candidate.Showing that the Ghttp://dx.doi.org/10.1371/journal.pmed.0030528.Please access these Web sites via the online version of this summary at minisite containing links to information about all aspects of malaria worldwide, including treatment, prevention, and current programs for malaria controlThe World Health Organization publishes a Medicines for Malaria Venture is a collaboration between public and private organizations  that aims to fund and manage the development of new drugs for treatment and prevention of malariadrug discovery and drug development (Wikipedia is an internet encyclopedia that anyone can edit)Wikipedia entries for  Plasmodium falciparum is a protozoan parasite that causes the most lethal form of malaria, a major human disease urgently in need of new targets for future antimalarial drugs. Targeting the blood stages of infection is particularly important since these stages are responsible for all of the symptoms and pathologies associated with the disease. Increased resistance to antimalarial drugs is inevitably linked to mutation of parasite targets and reflects the general problem of continual emergence of resistance to drugs developed against microbial targets. Indeed, the discovery of drugs and targets that minimize the likelihood of drug-resistant microorganisms was recognized as a Grand Challenge in Global Health -hypoxanthine  was added to each well, and samples were re-incubated for 18 h. Plates were harvested onto filters, dried, and assayed for [3H]-hypoxanthine. Individual 50% inhibitory concentration (IC50) values were determined for each drug singly, and those values were used to establish drug ratios used in combination studies. Combined IC50 values were determined for each drug in combination at 1:0, 3:1, 1:1, 1:3, and 0:1 ratios. A fractional IC50 value  was calculated for each drug-combination ratio and used to plot isobolograms -hypoxanthine incorporation Click here for additional data file.Figure S3P. berghei ANKA mouse model of malarial infection (D).Isobolograms see  are pres(184 KB PPT)Click here for additional data file.Table S1(20 KB XLS)Click here for additional data file.http://www.ebi.ac.uk/swissprot) accession numbers for the proteins discussed in this paper are human β2-AR (P07550); human heterotrimeric Gi (P63096); human heterotrimeric Gq (P29992); human heterotrimeric Gs (P63092); and PfHRPII (P90582).The Swiss-Prot (


Clinical trials of interventions designed to prevent severe falciparum malaria in children require a clear endpoint. The internationally accepted definition of severe malaria is sensitive, and appropriate for clinical purposes. However, this definition includes individuals with severe nonmalarial disease and coincident parasitaemia, so may lack specificity in vaccine trials. Although there is no “gold standard” individual test for severe malaria, malaria-attributable fractions (MAFs) can be estimated among groups of children using a logistic model, which we use to test the suitability of various case definitions as trial endpoints.A total of 4,583 blood samples were taken from well children in cross-sectional surveys and from 1,361 children admitted to a Kenyan District hospital with severe disease. Among children under 2 y old with severe disease and over 2,500 parasites per microliter of blood, the MAFs were above 85% in moderate- and low-transmission areas, but only 61% in a high-transmission area. HIV and malnutrition were not associated with reduced MAFs, but gastroenteritis with severe dehydration (defined by reduced skin turgor), lower respiratory tract infection , meningitis , and bacteraemia were associated with reduced MAFs. The overall MAF was 85%  without excluding these conditions, 89% (95% CI 88.4%–90.2%) after exclusions, and 95% (95% CI 94.0%–95.5%) when a threshold of 2,500 parasites/μl was also applied. Applying a threshold and exclusion criteria reduced sensitivity to 80% (95% CI 77%–83%).The specificity of a case definition for severe malaria is improved by applying a parasite density threshold and by excluding children with meningitis, lower respiratory tract infection (clinician's diagnosis), bacteraemia, and gastroenteritis with severe dehydration, but not by excluding children with HIV or malnutrition. The accepted definition of severe malaria is appropriate for clinical purposes, but Philip Bejon and colleagues show its specificity in clinical trials may be improved by a parasite density threshold and by excluding children with certain conditions. Malaria is responsible for over a million deaths every year, and most of those who die are children in Africa. Until a few years ago, not enough research was being done on malaria, but now many researchers are active in this field. Doctors describe some cases of malaria as being “severe.” Severe malaria in children is very hard to diagnose precisely. Current protocols for diagnosing severe malaria are very sensitive: that is, virtually all children who do have severe malaria will be correctly diagnosed as such. However, the protocols are not very specific: many children who do not have severe malaria, but whose symptoms are instead caused by other diseases, will be defined as suffering from severe malaria. This definition is acceptable for the clinical care of sick children, because it ensures that antimalarial drugs are given to all who might benefit from them, plus some additional children for whom those drugs are not required. However, this definition is not particularly useful for research purposes. When conducting a clinical trial aimed at preventing cases of malaria, it is important to evaluate whether the intervention being tested actually works. Therefore, a more specific method of calculating the number of malaria cases within a population is needed for this type of research.The current definition for diagnosing severe malaria includes a set of signs and symptoms that may be observed at the bedside or as a result of laboratory investigation, along with the detection of malaria parasites in the patient's blood. However, in many malarious areas, a large proportion of the population carries malaria parasites without signs of disease; at the same time, the signs and symptoms of malaria are shared with other diseases. The investigators here wanted to find out whether they could develop an accurate “case definition” of severe malaria that can be used in research.In this study, two groups of children were studied: first, 1,422 children admitted to the children's wards of the Kilifi District Hospital in Kenya, and second, 4,583 children from the surrounding community. Blood samples were taken in order to find out how common malaria parasites were in the children's blood, and standard clinical and laboratory data were also collected from the children admitted to the hospital. The researchers then compared these data using a computer and tried to find out whether, by excluding certain children who had particular signs, symptoms, or observations, from the diagnosis of severe malaria, they were able to improve the accuracy of their definition. Essentially, for each patient group, the authors calculated “malaria-attributable fractions,” i.e., the proportion of individuals studied whose disease was likely caused by malaria.The researchers found that in areas with low and moderate transmission of malaria, the proportion of individuals whose disease could be attributed to malaria was high—nearly 85%. In areas with a high transmission rate of malaria, this fraction was much lower, but could be improved by including only children with a high proportion of parasites in their blood. Importantly, the researchers were also able to increase the recognition of children with disease likely caused by malaria by excluding individuals who had also been diagnosed with gastroenteritis, lower respiratory tract infections, meningitis, and bacterial infection in the blood. If all of these individuals were excluded—so only individuals with more than 2,500 parasites per microliter in their blood were regarded as having severe malaria—the “malaria-attributable fraction” rose to 95%.These findings should not be directly used to change the clinical care of children with the signs and symptoms of severe malaria, but rather can be used within a clinical trial to create a “case definition” of malaria particular to that trial. This ability will help researchers more accurately find out whether the intervention being tested in their trial really does help to prevent cases of malaria or not.http://dx.doi.org/10.1371/journal.pmed.0040251.Please access these Web sites via the online version of this summary at Global Malaria Programme details the organization's activities in fighting malaria, and provides a number of helpful resources; a factsheet on children and malaria is also availableThe World Health Organization malaria resourcesThe US Centers for Disease Control and Prevention provides many “Medline Plus” encyclopediaGeneral information about malaria, including illustrations, is available from the Plasmodium falciparum [Severe falciparum malaria is an important end point for preventative intervention trials in its own right, and as a proxy for malaria-associated deaths. The current internationally accepted definition of severe malaria in children is based mainly on the presence of a limited set of bedside or laboratory observations in the presence of parasitaemia with asexual-stage lciparum . This delciparum . It is bThere is no “gold standard” methodology with which to identify individuals with “true” severe malaria rather than severe disease with incidental parasitaemia, so malaria-attributable fractions (MAFs) cannot be calculated by a simple numerator and denominator approach. Instead, we have fitted the risk of severe disease to parasite density as a logistic model, which allows MAFs to be estimated within populations . We haveThe case definition that we develop is not intended to limit treatment options for severe malaria, since the balance of risk and benefit will always favour the use of antimalarial drugs and other supportive clinical treatment in a sick child, even when there is a low probability of severe malaria. Rather, it is intended to maximize the discriminatory power of trials conducted to evaluate interventions to prevent malaria. It will also allow more accurate measurement of the disease burden in epidemiological studies.Plasmodium falciparum each year [The KEMRI Centre for Geographic Medicine Research (Coast) is located at Kilifi District Hospital, Kenya. Government-employed clinical officers admit children from the hospital outpatient department to the paediatric ward where research was conducted. The hospital serves ∼240,000 people, who belong mainly to the Mijikenda group and are rural farmers. Children in the surrounding area receive up to 120 mosquito bites infective for ach year . Approvaz scores were calculated using reference data from the American National Centre for Health Statistics (NCHS) using Epi Info 6.04b . Severe malnutrition was defined as a weight for age z score below −3 or bipedal oedema and characteristic skin and hair changes. Lower respiratory tract infection (LRTI) was defined by the clinician's diagnosis on discharge, using a chest X-ray where possible, although WHO integrated management of childhood illness (IMCI) definitions for mild and severe LRTI were also considered [From 01 August 1998 to 30 July 2002 we prospectively collected standardised clinical, anthropometric, and laboratory data on all children admitted to the paediatric wards (described in detail elsewhere ). Subgrohttp://www.beckmancoulter.com/). Thick and thin blood smear was stained with 10% Giemsa and examined at 1,000× magnification for asexual forms of P. falciparum and results expressed per microliter using the automated red and white cell indices.Complete blood counts were performed using an automated counter  as previously described [Blood was aerobically cultured for pathogenic bacteria  were chosen to represent relatively low-, moderate-, and high-transmission intensities respectively. Entomological inoculation rates were 10, 22–53, and 42 infective bites/person/year, respectively . The numThe initial study was limited to children from three specified locations according to the availability of community cross-sectional surveys. These children were admitted or had blood samples taken in the community between 01 August 1998 and 01 August 2005. 1,422 children were admitted to Kilifi District Hospital with signs of severe disease during this period, and 4,853 samples were taken in the community. The distribution by age and location of these children is given in To study comorbidities and clinical presentations, a more restricted subset of these children was used, for whom detailed clinical information was available. These children were admitted between 01 August 1998 and 30 July 2002. 1,361 children had signs suggestive of severe disease.p/1 − p)= a + τbx, where p is the probability of severe disease , x is the density of parasitaemia, and τ is the power function, which improves the numerical stability of the maximum likelihood estimation. The coefficient b in the logistic model can then be used to calculate the risk of malaria for each individual. The risks of a group of individuals can be summed to estimate the proportion of the group having “true” severe malaria rather than another cause of severe disease with coincident parasitaemia. This gives the positive predictive value, or MAF, for the group analysed. Sensitivity and specificity can then be calculated from the MAFs.Parasite densities from the children with signs of severe disease (considered “cases”) and from children in cross-sectional surveys (considered “controls”) were used to model the relationship between parasite density and severe disease. The method has been described previously . BrieflyThe model was repeated in different age groups, locations, and for different comorbidity patterns. Confidence intervals (CIs) were estimated by bootstrapping, using 5,000 iterations. The impact of age and location was modelled on a data set covering 1997–2004, restricted to cases of severe disease presenting from the three geographical locations used to establish the cross-sectional datasets. The impact of various comorbidities was studied on all admissions between 1998 and 2002, when systematically collected information on other clinical features was available to define comorbidity. The dataset was not large enough to allow models for comorbidity to be corrected by age, location, and season.MAFs and sensitivities are shown in The MAFs (with CIs) for children with different clinical features and comorbidities are shown in When months associated with greater malaria transmission (“rainy season”) and months associated with lower malaria transmission (“dry season”) were analysed separately, the MAFs for all parasitaemic children were higher during the rainy season, but at a threshold of 2,500 parasites/μl, the MAFs during the rainy and dry seasons were similar.HIV and malnutrition were associated with only slight reductions in MAFs. The lowest MAFs were seen among children with meningitis, and children with bacteraemia had moderate reductions in MAFs. Gram-negative and gram-positive bacteraemia were associated with markedly different MAFs . HoweverChildren for whom a final diagnosis of LRTI was made by a clinician had a low MAF. However, low MAFs were not seen among children who met WHO IMCI criteria for LRTI of any severity. Although a lower MAF was seen among children in whom crepitations were heard on chest auscultation, the MAF among children with a clinician's diagnosis of LRTI was lower still.The overall MAF rose from 85% (95% CI 83.8%–86.1%) to 89% (95% CI 88.4%–90.2%) after excluding gastroenteritis with severe dehydration, LRTI, meningitis, and bacteraemia, and then to 95% (95% CI 94%–95.5%) when a threshold of 2,500 parasites/μl was used. The sensitivity fell to 80% (95% CI 77%–83%) overall.Children with falciparum parasitaemia in association with clinical signs of severe malaria had an MAF of 85%, which rose to 95% when a threshold of 2,500 parasites/μl was applied and children with meningitis, lower respiratory tract infection (clinician's diagnosis), bacteraemia, and gastroenteritis with severe dehydration were excluded. Excluding children with HIV or malnutrition did not improve the case definition.We have previously described severe falciparum malaria in children admitted to hospital by identifying the children at greatest risk of death . Howevern = 5,500 for 90% power. After applying exclusion criteria and the threshold of 2,500 parasites/μl, the apparent efficacy would be 48% . Although the apparent efficacy estimate is more accurate , the sample size has increased slightly because of reduced sensitivity. Were the threshold parasitaemia applied without exclusion criteria, the apparent efficacy would be 46% . However, the effect will depend critically on transmission intensity and the incidence of severe nonmalarial disease , so these calculations should be considered illustrative rather than definitive.It is impractical to define a threshold parasitaemia for every age group, village, and season, so any threshold used in a trial or epidemiological study must inevitably be a compromise. Higher thresholds were required in older age groups, and at higher transmission intensities. Data from the high-transmission area support a high threshold , but this would be associated with a large reduction in sensitivity if applied to the low- and moderate-transmission areas, and transmission may vary considerably even in a restricted area . Based oSevere malaria comprises three distinct, though often overlapping, clinical syndromes: impaired consciousness, respiratory distress, and severe anaemia . MAFs weChildren with coexistent HIV or malnutrition should not be excluded from a case definition of severe malaria, as the high MAFs indicate that malaria is often the immediate proximate cause of the life-threatening illness. A history of diarrhoea was associated with reduced MAFs, but this effect was found mainly among children with reduced skin turgor (a sign of intracellular dehydration). Children with diarrhoea but normal skin turgor had a high MAF. Thus, skin turgor appears to distinguish severe dehydration with extravascular fluid depletion in gastroenteritis from intravascular fluid depletion without signs of marked tissue dehydration in malaria .A clinical syndrome of LRTI at admission (according to WHO IMCI guidelines) was not associated with reduced MAFs. However, when clinicians made a final diagnosis of LRTI, they successfully identified a group of children with low MAFs. This is surprising, since the deep breathing produced by malaria-related acidosis is easily confused with respiratory disease . Of the Proven bacterial meningitis should exclude a case from consideration as severe malaria. Among children with bacteraemia the MAFs were reduced, but not by as much as those for meningitis or LRTI. It may be that bacteraemia is the primary cause of severe disease in some children but a consequence of severe malaria in other children. When enteric gram-negative organisms and gram-positive organisms were examined separately, the reduction in MAF was confined to gram-positive organisms. Bacteraemia with enteric organisms may often be a consequence of malaria infection in this group of children, whereas gram-positive bacteraemia may be unrelated.What are the limitations of this study? Data from all admissions with severe disease during the study period were used to examine the impact of comorbidity, but data used to establish patterns of asymptomatic parasitaemia in the community were necessarily from a subsample, limited geographically and temporally. It is possible that the true distribution of asymptomatic parasitaemia in the whole of Kilifi district might be different from that used in this analysis. Although this might bias the calculated MAFs, this consideration applies equally to each subgroup for which MAFs were estimated. Conclusions based on comparisons between comorbidities and all cases are therefore still justified.Hospital inpatient studies on the correlation between diseases are vulnerable to Berkson's bias . If, forData on funduscopy was not available in this study. Retinal changes specific to cerebral malaria are well described , but reqThe protocol for HIV testing changed during the study, but the MAF among HIV-positive children was calculated from the group admitted after October 1999. HIV data were available on 92% of these children, and so significant bias seems unlikely.In an single district in Kenya, with transmission ranging from less than one up to 120 infective bites per year, typical of the majority of transmission setting in sub-Saharan Africa ,18, a th


Malaria, both with or without convulsions, is a serious hardship for people living in endemic areas, especially in sub-Saharan Africa. Community references to malaria, however, may encompass other conditions, which was collectively designated malaria-related illness (MRI). Inasmuch as the presence or absence of convulsions reportedly affects timely help-seeking for malaria, a local comparison of these conditions is needed to inform malaria control.Vignette-based EMIC interviews (insider-perspective interviews) for MRI with convulsions  and without convulsions  were developed to study relevant features of MRI-related experience, meaning and behaviour in two rural communities in Ghana. These semi-structured interviews elicited both qualitative narrative and categorical codes for quantitative analysis. Interviews with 201 respondents were conducted.The conditions depicted in the vignettes were well recognized by respondents and named with various local terms. Both presentations were considered serious, but MRI-CP was more frequently regarded potentially fatal than MRI-CN. More than 90.0% of respondents in both groups acknowledged the need to seek outside help. However, significantly more respondents advised appropriate help-seeking within 24 (p = 0.01) and 48 (p = 0.01) hours for MRI-CP. Over 50.0% of respondents responding to questions about MRI-CP identified MRI-CN as a cause of convulsions.Local comparison of MRI-CP and MRI-CN based on vignettes found a similar profile of reported categories of perceived causes, patterns of distress, help-seeking and preventive measures for both presentations. This differs from previous findings in sub-Saharan Africa, which assert communities regard the two conditions to be unrelated. The perceived relationships should be acknowledged in formulating strategies to control malaria through timely help-seeking and treatment to reduce childhood mortality. According to the WHO about 1.3 million people died of malaria in 2003, and about 90% of these deaths occurred in sub-Saharan Africa ,5. Many et al. [Practical questions remain about how this cultural epidemiology of MRI-CP relates to timely, appropriate health-seeking by caretakers. Many studies have reported that MRI-CN is generally treated first at home – either with modern pharmaceuticals , or herbal medications, or both – and caretakers seek outside help only when the illness persists or when they observe a high fever ,10,13-16et al. , on the To explain locally perceived relationships between MRI-CP and MRI-CN, and to consider their practical implications for local management and timely, appropriate help-seeking, this study compares local illness experiences, meaning and behaviour associated with the two conditions. It aims to clarify their common and distinctive feature, and to consider implications for local management and timely, appropriate help-seeking. Based on the framework for local classification, the study examines the assertion that they are locally perceived to be two distinct conditions, as reported in the literature -9.This study was conducted from October, 2002 to April, 2004 in two malaria-endemic villages, Galo-Sota in the Keta District and Obosomase in the Akuapim North District of Ghana. Keta District is located in the coastal savannah vegetation zone of the Volta region, where about a third of the total surface area is covered with lakes and ponds. The district has a population of 137,751 , consisting mainly of the Anlo patrilineal descent group (98.8%). The Anlo language is one of the closely related dialects spoken among the Ewe-speaking people of Ghana . The Anlo people are predominantly subsistence food-crop farmers, but they also cultivate shallot . Some are fishermen and petty traders. Galo-Sota is a rural village with a population of about 6,000 to 7,000. A health post is situated at the centre of the village, staffed by a nurse/midwife, two community nurses and two auxiliary workers. Malaria was the most common health problem treated at the community health post in 2002. A tributary of the Volta River passes through the village, demarcating a boundary between Galo and Sota, which together constitute Galo-Sota.The Akuapim North District in the eastern region of Ghana is situated in the forest zone. The district population is 113,915, according to the last census . The Akuapim-Twi-speaking people, members of the Akan matrilineal descent group, predominate in the district. These Akuapim people are also mainly food-crop farmers and petty traders. Oil palm, a cash crop, is cultivated on a limited scale. The district is currently being prepared as a designated site for a malaria vaccine trial. Among health science activities in the area is a Centre for Scientific Research into Plant Medicine . Obosomase  is the rural study village in the Akuapim North District. It has a community clinic staffed by a nurse/midwife, a community health nurse and one auxiliary staff. As in Galo-Sota, malaria was the most common health problem treated at the community clinic in 2002.Two EMIC interview tools were developed locally to study the relationship between sociocultural factors and appropriate treatment-seeking for children up to five years of age. EMIC interviews are locally adapted instruments for assessing representations of illness or specified health problems from the perspective of affected persons, their family or community members. They elaborate the distribution of local insiders' illness-related experience, meaning and behaviour integrating qualitative and quantitative approaches ,18. The Respondents aged 20 years or more were selected randomly from community registers to participate in the interviews. However, younger respondents between the ages of 20 and 25 years of age were unwilling to participate in the interview using the vignette depicting MRI with convulsion, which introduced some age difference between the two groups of respondents. The reason for refusal was, they claimed, that they did not have any experience to talk about. Informal discussions, however, revealed that some people believed that if they talked about convulsions, this might bring that condition to their children. This attitude was observed in both communities. One hundred interviews were conducted using vignettes depicting MRI-CN and 101 using vignettes depicting MRI-CP. Respondents were evenly distributed by sex and community. Few of those originally selected eventually refused to participate in either of the interviews – two men and one woman at Obosomase and three men at Galo-Sota. The dissenting individuals were replaced from the registers.Interviews were conducted by the first author in the local languages, and data were recorded by a research assistant with a degree in sociology, who was trained to record both qualitative and quantitative interview data. The EMIC instrument was pre-tested to refine it and gain experience. The pretesting showed it was unnecessary to tape record the interviews, inasmuch as the data were recorded very well by the research assistant.Data from the two communities were pooled for this analysis. Item-specific qualitative narrative data were entered into a word processor (Microsoft Word) and imported in a structured format for automatic coding, referencing text segments of EMIC interview items in MAXqda, a programme for textual analysis . These dQuantitative data were double entered in DOS EpiInfo version 6.04 and subsequently analysed with the EpiInfo Windows version 3.3 . The freReported duration from illness onset to observe, wait or treat at home before seeking-help from outside the home for the children presented in the two vignettes was analysed to compute anticipated timely, appropriate help-seeking for MRI-CP and MRI-CN within 24 and 48 hours. The reported timeliness was then compared for the two vignette groups.The socio-demographic characteristics of respondents are presented in Table The children presented in the two vignettes were the focus of interview questions. Local names or terms used to describe their illnesses and their approximate English translations or meanings are presented in Table This kind of illness kills children easily, especially if parents do not respond quickly to treating the child."Respondents in the MRI-CP group appeared somewhat more likely than MRI-CN respondents to consider the condition "usually fatal" (39.6% against 27.0%). Narrative elaborated concerns about mortality: ""As for this problem, it is a very serious one. If it does not kill the child then it could destroy the child's ability to reason properly.""This is a very serious problem; so long as the child is still very small she may die if not treated properly and early."For MRI-CN children, mortality was likely to be associated with some vulnerability or neglected treatment: Fever can kill children because people do not consider the disease serious when it is starting, so before they realize it, it has already become worse for the child. What I mean is that it is not a condition that should usually kill, but if it is not seen and treated early, it does kill.""In both situations, a majority of respondents (98.0% for MRI-CP and 96.0% for MRI-CN), said it was necessary that someone stays at home to care for the sick child. The mother of the child was the obvious choice for 97.0% of MRI-CP and for 95.0% of the respondents for vignette depicting MRI-CN.onvulsion-related symptoms were more prominent in the MRI-CP group, and more frequently reported as most troubling. On the other hand, MRI-CN respondents reported significantly more fever-related symptom and identified them more frequently as most troubling. Non specific symptoms, except for breathlessness, were also most prominent in responses of the MRI-CN group.Reported symptoms of both conditions are presented in Table In most cases, the child's jaws are locked, and the child becomes very stiff. Also, foaming fluid comes from the mouth. In some cases the child becomes unconscious."The following narratives indicate how people explain the symptoms presented in the vignettes. A woman speaking about convulsive illness characterized typical features: "Among most typical symptoms, the child begins to shiver and all of a sudden becomes very stiff and hot, and rolls the eye balls."Another respondent explained, "The first sign is that the child feels very cold and then at certain times feels hot. It is also possible that the child loses weight and sweats so much. The child's eyes also turn yellow because of the fever. The colour of his urine will look yellowish, and he may become very weak."A man explained typical symptoms for MRI-CN: "The child's body becomes hot and this makes her cry a lot. She may complain of headache, and feels cold and shivers. She may also find it difficult to eat; her eyes become yellow, and she looks pale and weak."A woman explained, "unconsciousness and stiffness. For MRI-CN respondents, most troubling symptoms more frequently reported were yellowish eyes, refusal of food, and weight loss. Weakness was identified by some respondents in both groups as most troubling.Most troubling symptoms reported more frequently by MRI-CP respondents included concern about the course of illness  and sadness, anxiety or worry . However, financial concerns (unavailability of funds for treatment and inability to work for money), which leads to anxiety, were frequently reported as the most troubling categories of distress for the family, . Concern about the course of illness was also considered one of the most troubling categories of distress for the family . These were common features of both groups without statistically significant difference between them.Among features of distress, apart from somatic symptoms of malaria, a number of problems were reported to affect the families of the children in the vignettes with and without convulsions (as specified by percent reported/ fraction spontaneous). Nearly all respondents reported loss of income for families of the affected children , Generally, if a child becomes ill, the parents are worried because they do not know what could happen to their child, and in addition to that, it could lead to financial problems for the family." Another respondent lamented: "The child's condition can adversely affect her in the future, so the parents would become so bothered and worried about the child, especially if they do not have money. The child could become deaf and mute or have a mental problem. I have seen one like that before."The following representative narratives explain the importance of income loss to the family of a child with MRI. An MRI-CP respondent elaborated: "Fever kills so the family would be worried. Also money issues could be a problem for them."Referring to MRI-CN, a man said: "It is very normal that when your child is sick, you become worried, especially if you do not have money."Another respondent explained: "spirits, phlegm, worm infections and atridii/asra/malaria; this last category refers to local terms for MRI as a cause of convulsions. Most frequently reported perceived causes of MRI by MRI-CN respondents were mosquito bites, eating too much fatty or oily food and heat from the sun.The prominence of many perceived causes differed for the two groups Table . The mosSome people claim that if children play on refuse dumps they easily get convulsion, but I also think that a child can get it through mosquito bites, because these give fever, which can lead to this condition. Worms can also cause a child to get this condition, because worms release some substances into the child's stomach, which in turn gives the child phlegm. And this can cause a convulsion. Evil spirits can also cause children to have this illness."Overlapping meanings were also reported in respondents' accounts of perceived causes. For example, a woman in the MRI-CP group explained: "Malaria is the major cause, but in some cases, spiritual forces can also cause a convulsion. It also depends on the kinds of food that children take, like unbalanced diet."A man said: "This condition could have been caused by worm infestations or houseflies that perch on food and contaminate it before it is eaten. Sometimes too mosquito bites can cause it."Explaining MRI-CN, a woman commented: "Maybe she wasn't eating good food. Bad food like fatty/oily foods can lead to this problem. I know that mosquito bites or living in a dirty environment could also cause it. And exposure to the heat from the sun can also cause it."Another said: "Respondents reported various self-help options for both conditions. The most prominent among reported sources of self-help for MRI of both types was herbal-based remedies for drinking Table . Among pIn some cases they say that water kept in a 'banku pot'  overnight, mixed with urine, can be used to bathe the child for relief. Herbal preparations can also be used to bathe the child. Some people prefer to prepare some herbs for the child to drink. Some also give honey, while some people may buy drugs from the chemical sellers."A woman emphasized the value of various traditional remedies for MRI-CP: "Some of the possible actions may be to buy drugs from a chemical seller for the child to drink or prepare herbs for drinking or enema."Commenting on MRI-CP vignette, a man indicated how various interventions might all be appropriate: "Some medicine could be given at home as a measure to reduce the severity of the illness. The medicine could be bought from the drug stores if there are no leftovers. Some herbal medications can also be given to the child."A respondent in the MRI-CN vignette group indicated the value of diverse treatment for that condition as well: "The family may decide to buy drugs for the child; they could also decide to prepare herbs for the child to drink."Another said: "The need to seek help outside the home was reported by nearly everyone for both conditions Table . More MRSimilar outside sources of help were identified by respondents in both groups Table . AlthougIf the herbs used at home do not work other people who know more herbs, like traditional healers, could be consulted. The child could also be taken to the clinic or hospital, but this costs money."Commenting on outside help-seeking for MRI-CP, a woman explained that home remedies at some point were not enough: "As soon as it is clear that what is done at home does not work, the child would have to be sent to a clinic or hospital. The hospital or clinic is the best place, and the family must go, but they can also see a traditional healer for treatment."Another observed: "A clinic or a hospital should be the best places to go but some traditional healers also know about herbs that work."Some MRI-CN respondents like this woman, compared modern and traditional health care providers favourably: "As soon as the child's condition does not get better after the home treatment, the family should consult a doctor."A man emphasized the importance of not waiting too long before getting help from a doctor: "preventing mosquito bites, staying less in the sun, maintaining personal hygiene, environmental cleanliness, drinking clean water, avoiding fatty or oily foods, and reducing strenuous or hard work/play. These were reported more frequently by respondents in MRI-CN group. Preventive measures based on magico-religious ideas were mentioned more frequently in the MRI-CP group. Measures frequently reported by similar percentages in both groups included taking medications regularly  and deworming children regularly.Most respondents in both groups (74.3% MRI-CP and 84.0% MRI-CN) said the conditions in the vignettes could have been prevented, there was, however, a borderline significant difference (p = 0.06). Categories of preventive measures suggested for both presentations were similar , but the rates for both are relatively low, and far below the designated Abuja target. The percentages were higher for 48 hours , but still lower than the 60.0% specified in the Abuja target for 24 hours (15). This could mean that the message of the priority of timely treatment has either not yet reached these communities or it is not compelling enough to motivate action and hence needs reinforcement.It is notable that despite the distinctiveness in many studies of MRI-CP and MRI-CN illnesses, 57.4% of respondents in the MRI-CP group have reported that malaria is a cause of convulsions, and 13.9% said malaria is the most important cause of convulsions. The emerging local awareness of the link between mosquitoes, malaria and convulsions should be strengthened to reinforce the priority of timely, appropriate treatment for febrile malaria without convulsions. Information, education and communication (IEC) have important roles to play in that regard. More people acknowledge the value of home-based treatment for MRI-CN, consistent with a policy to promote that option for uncomplicated malaria. Reliance on traditional healers, especially for MRI-CP, however, remains a problem, inasmuch as this results in many children not receiving timely antimalarial treatment. The use of a mix of traditional remedies  and biomedical treatments are consistent with the literature -12,22.For both conditions, findings also suggest approaches to prevention that are related to local perceived causes, mostly involving avoidance of identified causes. Most people, similar in both groups, recommended regular medications as a preventive measure, indicating favourable prospects for implementing intermittent preventive treatment (IPT) for pregnant women. The finding suggests it may be feasible to introduce intermittent preventive treatment for children under five years of age to reduce morbidity and mortality in this vulnerable age group. When evaluating such policy options, the risk of drugs being used inappropriately should be weighed against prospects for reducing mortality.Widespread recommendations to avoid mosquito bites to prevent both conditions indicate good prospects in these communities and others like them for acceptance of insecticide-treated bednets. The idea that uncomplicated malaria may progress to convulsions may further reinforce such an approach to prevention. These issues would need emphasis when developing IEC as an intervention to reduce MRI-related morbidity and mortality in the study communities.The study shows that despite the complexity of local experience, meaning and behaviour with respect to malaria-related illnesses, it is possible to identify the distribution of categories and explain local illness behaviours, their sociocultural determinants, and practical implications in endemic local rural communities. Relating results to timely help-seeking and malaria prevention suggests ways of incorporating local relevance ideas into the design and implementation of local programme strategies, especially IEC, an indication of how cultural epidemiology may inform malaria control activities to make them sustainable to reduce MRI-related morbidity and mortality.Though, this study was carried out in two rural communities in southern Ghana findings may be generally applicable in most part of Ghana, especially the southern half of the country. However, local variations must be considered when interpreting findings for areas outside the study localities.The author(s) declare that they have no competing interests.CK Ahorlu was involved in the conception and design of the study, fieldwork, data management, analysis, interpretation and writing of this paper.KA Koram was involved in the conception and design of the study, and data management.C Ahorlu was involved in the conception of the study, fieldwork, and data management.D de Savigny was involved in analysis and interpretation of data, and writing of this paper.MG Weiss was involved in the conception and design of the study, data analysis, interpretation and writing of this paper.The study was approved by the institutional review boards of Noguchi Memorial Institute for Medical Research and the Swiss Tropical Institute. It was also reviewed by the WHO/TDR Ethical Review Committee.