Plasmodium infection levels, including parasite/host genetics, immunity, and exposure. Here, we examine the roles of host genetics and exposure in determining parasite density, and test whether effects differ with age. Data for 1,711 residents of an eastern Ugandan community were used in pedigree-based variance component analysis. Heritability of parasite density was 13% (P < 0.001) but was not significant after controlling for shared household. Allowing variance components to vary between children (< 16 years) and adults (≥ 16 years) revealed striking age differences; 26% of variation could be explained by additively acting genes in children (P < 0.001), but there was no genetic involvement in adults. Domestic environment did not explain variation in children and explained 5% in adults (P = 0.09). Genetic effects are an important determinant of parasite density in children in this population, consistent with previous quantitative genetic studies of Plasmodium parasitaemia, although differences in environmental exposure play a lesser role.Many factors influence variation in  Genetic variation among individuals is known to profoundly affect susceptibility to malaria, with a growing number of genes identified as conferring resistance against infection.9In terms of both vaccine and drug development and evolutionary biology, severe clinical malaria has been the phenotype of interest,29Plasmodium parasitaemia in this community. To separate these effects, we incorporate information on all known genetic relationships within and between houses, allowing robust estimation of the heritability of blood-stage infection levels. Bivariate variance-component models are then used to determine whether familial, household, and environmental involvements vary according to the age of the host.We previously showed significant household clustering of malaria parasitaemia among a rural community living in an area of high (stable) transmission in eastern Uganda.A cross-sectional study was conducted between June and December 2008 in four contiguous villages in Mulanda subcounty, Tororo District in eastern Uganda, a region hyperendemic for malaria.Further details of the study area and procedures are presented elsewhere.Plasmodium falciparum and 6.0% were P. malariae; no other species or mixed infections were seen.A standardized questionnaire was administered to all adults and primary caregivers of children to record details of medical history and protective behaviors. A single finger-prick blood sample was obtained from all enrolled individuals for preparation of thick films for quantification of malaria parasite density using light microscopy. Parasite densities were calculated by blinded counting of the number of asexual parasites per 200 leukocytes , assuming a leukocyte count of 8,000/μL by two independent microscopists. Parasite density was reported as the arithmetic mean of the two readings. In addition, a rapid diagnostic test for malaria  was performed on all participants with fever (temperature > 37.2°C) or reported history of fever in the previous 24 hours. Those with a positive test but no evidence of danger signs of severe malaria were diagnosed with uncomplicated malaria and treated with artemether-lumefanthrine  in accordance with national guidelines. Participants found to be suffering from danger signs of severe malaria were referred to the local health facility for case management. Thin films from a subsample of 20% of parasite-positive participants were read for species identification, showing that 94.0% were Pedigrees were constructed by interviewing the primary caregiver or household head from each household to record biological relationships among all household members and to identify other first- or second-degree relatives living in the study villages, thereby identifying genetic links between households. Households within the same family compound shared the same location and peri-domiciliary environment and as such, were treated as single units. Individuals were defined as belonging to the same extended pedigree if they were related to anyone else in the pedigree or were married to anyone in the pedigree. Pedigrees were assembled and indexed using PEDSYS (Dyke) and visualized using Cranefoot .33High-resolution (0.6 m) QuickBird satellite data  were used for geo-referencing roads and potential mosquito-breeding sites. Geographic data were compiled, and maps were created using ArcGIS 9.2 .Plasmodium infection. Parasite densities from all individuals, regardless of clinical malaria status and reported use of medication in the preceding weeks, were included in the analyses. Heritability estimation was undertaken using variance-component analysis to estimate the relative contribution of (1) additive genetic effects, (2) domestic environmental effects, (3) individual- and household-level covariates, and (4) unexplained residual variation to total variation (VT) in density of Plasmodium spp. parasitaemia. In brief, this approach incorporates information on genetic relationships within and between households to partition total phenotypic variation into its genetic, household, and other causes. Incorporation of a relationship matrix into a random-effect model, built from the pedigree described above and containing the expected degree of genetic relationship between all participants in the study, thus allows the covariance between relatives to depend on the degree of relatedness between them, providing an estimate of the total cumulative effect of individual genes (the additive genetic effect) on phenotypic variation. This is essentially a generalized animal model, an established quantitative genetic method that has been used extensively to model biological and disease phenotypes.35The phenotype under study was the density of blood stage P < 0.1) covariates were excluded sequentially to generate a minimal adequate model. Excluded covariates were retested in the minimal model to confirm lack of significance.Models were estimated by means of a maximum likelihood-based variance-decomposition approach implemented in the computer package SOLAR 4.2.0.Plasmodium parasitaemia entirely to a random, individual-specific effect .Subsequently, a series of nested multivariate mixed-effect linear-regression models were investigated. The sporadic model attributes variation in levels of  effect e. The houeffect ec, allowinPlasmodium parasitaemia between children (< 16 years) and adults (≥ 16 years), separate variance components were fit for each age group using the approach of Towne and others and Breitling and others.hetdist option, which creates an extra parameter in the model to describe the distribution of the phenotype, was applied in all analyses. The relative contribution of fixed covariates to total phenotypic variance in the final model was estimated by comparing the trait standard deviation (SD) in models with and without fixed covariates.To determine whether there were differences in heritability of density of P < 0.001). There were, however, no statistical differences in the size or relative socio-economic status of participant and non-participant households.Of the 2,334 individuals for whom family structure was established, 1,711 provided household information and parasitological data. This represents 72.6% of the enumerated population in the four study villages. Comparison with the total enumerated population showed that the final study sample undersampled adult males (Plasmodium infection was 38.5% (geometric mean density = 914 parasites/μL). Parasite density peaked between 3 and 5 years  and declined throughout childhood and adolescence. Total variance (VT) in log-density was 14.17 in children (< 16 years), falling to 5.21 in adults (≥ 16 years). There was no clear sex dependency. Findings from preliminary linear-regression models of logistically transformed density ) reflect the negative binomial regression analysis presented in the accompanying paperN = 1,046; 56.7% of the participant population).Overall, prevalence of www.ajtmh.org). To explore whether this may result from an age–genotype interaction , analysis was repeated after age stratification (< 16 years and ≥ 16 years); data for 5,586 and 214 informative relative pairs were available for children and adults, respectively. Covariates included in the child model were age group, bed-net use, education level of the household head, and residential location ; the adult model was adjusted for age group and residential location (proximity to rice-growing area). In children, the data were best described by a polygenic model, with no household clustering of infection (χP < 0.001); variation in density in adults was best described by a household model, with no additive genetic effect (χP = 0.09) .After adjusting for associated covariates when modeling parasite log-density, the effects of household and familial clustering could not be separated for this study population ; the significance of the age-specific genetic effect remained when controlling for either a general or age-specific household component (P = 0.04). In contrast, after controlling for an additive genetic effect  and household-effect components (for adults only) emerged as the most realistic reflection of the underlying structure of the density of Plasmodium infection levels in a rural Ugandan population after controlling for individual characteristics and environmental effects. Initial results suggested that heritability for asymptomatic Plasmodium parasitaemia (log-density) was as low as 5%. More detailed modeling allowing for age-dependent effects, however, revealed striking differences in heritability and other sources of between-individual variation in malaria parasitaemia between children (< 16 years) and adults (≥ 16 years). Results indicate that, in children, density of Plasmodium parasitaemia in this Ugandan community is controlled to some degree by additive genetic factors, which account for approximately one-quarter of the phenotypic variation. This is remarkably consistent with previous quantitative genetic studies conducted in several epidemiological settings.Analyses presented here focus on the influence of familial and household factors on Plasmodium parasite density reported here for children (26%) and previous observations for asymptomatic parasite density and/or parasite density during clinical episodes in population cohorts from Thailand, Sri Lanka, Tanzania, and Senegal.23There is a remarkable similarity between heritability of Plasmodium parasitaemia, although the approach has been used previously to investigate age and sex differences in heritability of human hookworm infection.The genetic effects for malaria parasitaemia observed here seem to fundamentally differ between children and adults (defined as ≥ 16 years), pointing to a declining influence of genetics on the control of parasite density with age in this population. To our knowledge, the bivariate variance-component approach adopted here  represents a new approach for investigating age–genotype interactions in the control of Genetic differences between individuals may play an important biological role during the development of anti-malarial immunity in childhood. For example, genetic contributions to acquired immunity have been previously shown,Plasmodium densities in adults and no effect on densities in children. Substantial household clustering of P. falciparum cases has previously been observed in genetic studies in Sri LankaOne pertinent difference between this and other studies of heritability of malaria is the relative influence of the household. We observed only a marginal effect of house on When interpreting the presented results, it is important to recognize that heritability is a population-specific measure, and our estimates are likely to be conservative. The feasibility of this approach to statistically separate the contributions of different variance components also depends on the sample size, pedigree and household structures, and available data for potentially confounding covariates, although studies do suggest that the impact of pedigree structure on precision and accuracy of heritability estimates may be minimal for purely additive genetic effects.Plasmodium infection in children in this population, suggesting that genetics plays a determinant role in the outcome of an infection before the development of immunity. In contrast, differences in domestic environmental exposure play a lesser role in this area of high (and stable) transmission. Large genome-wide association studies of children with differing parasite densities and different antibody-response profiles should allow identification of the genetic determinants of naturally acquired immunity,In conclusion, these results clearly show that there are major human genetic effects influencing asymptomatic


Burkitt lymphoma, a childhood cancer common in parts of sub-Saharan Africa, has been associated with Epstein Barr Virus (EBV) and malaria, but its association with human immunodeficiency virus (HIV) is not clear.p = 0.03). ORs for Burkitt lymphoma increased with increasing antibody titers against EBV (p = 0.001) and malaria (p = 0.01). Among HIV negative participants, cases were thirteen times more likely than controls to have raised levels of both EBV and malaria antibodies . Reported use of mosquito nets was associated with a lower risk of Burkitt lymphoma .We conducted a case-control study of Burkitt lymphoma among children (aged ≤15 years) admitted to the pediatric oncology unit in Blantyre, Malawi between July 2005 and July 2006. Cases were 148 children diagnosed with Burkitt lymphoma and controls were 104 children admitted with non-malignant conditions or cancers other than hematological malignancies and Kaposi sarcoma. Interviews were conducted and serological samples tested for antibodies against HIV, EBV and malaria. Odds ratios for Burkitt lymphoma were estimated using unconditional logistic regression adjusting for sex, age, and residential district. Cases had a mean age of 7.1 years and 60% were male. Cases were more likely than controls to be HIV positive (Odds ratio (OR))  = 12.4, 95% Confidence Interval (CI) 1.3 to 116.2, Our findings support prior evidence that EBV and malaria act jointly in the pathogenesis of Burkitt lymphoma, suggesting that malaria prevention may decrease the risk of Burkitt lymphoma. HIV may also play a role in the etiology of this childhood tumor. Plasmodium falciparum malaria have been associated with the etiology of Burkitt lymphoma. At least 90% of endemic Burkitt lymphoma cases are thought to be EBV-associated Plasmodium falciparum by the age of 10 months Endemic Burkitt lymphoma is a common childhood cancer in parts of sub-Saharan Africa, including Malawi Epidemiological evidence for an association between HIV and endemic Burkitt lymphoma is more uncertain This case-control study was nested within a larger study of childhood cancer conducted at the main hospital in Blantyre, Malawi, between July 2005 and July 2006. All 305 children aged 15 years or younger with a provisional diagnosis of cancer admitted to the pediatric oncology ward in Blantyre were recruited into the larger study. Preliminary clinical diagnoses of cancer were made by one investigator (EM) and were confirmed by histology, cytology or other laboratory investigations where possible. The study included 148 cases, 109 (75%) of whom were histologically diagnosed with Burkitt lymphoma, and 104 controls, 73 (74%) of whom were histologically diagnosed with other conditions . Just ovFive local nurses were employed and trained to recruit children and their mothers into the study and to administer standardized questionnaires. The parent or guardian of each child was approached and invited to participate in the study and provide written informed consent for their child to be included in the study. All children seen in the pediatric oncology ward with suspected cancer were routinely tested for HIV infection. The mother of each child was also asked to consent to be interviewed and also provided a serologic sample for testing for antibodies against HIV, EBV, malaria and syphilis. Appropriately trained staff provided pre- and post-HIV test counseling. Mothers of 102 (69%) cases and of 80 (77%) controls consented and were interviewed about demographic and socio-economic factors, their child's birth, household characteristics and their own sexual and reproductive histories. Ethical approval for the study was obtained from the Oxford Tropical Research Ethics Committee and the Malawian College of Medicine Research and Ethics Committee.Plasmodium falciparum were measured for 139 (94%) cases and 96 (92%) controls and also for 100 (98%) mothers of cases and 77 (96%) mothers of controls, at the Centre for Clinical Vaccinology and Tropical Medicine in Oxford using an Enzyme-linked ImmunoSorbent Assay (ELISA) Plasmodium falciparum schizont extract (PfSE) as the malaria antigen, which has been used elsewhere HIV serostatus was determined on site for 146 cases (99%) and 93 controls (90%) and also for 97 (95%) mothers of cases and 75 (94%) mothers of controls using Determine HIV  as a screening test and Uni-Gold™ HIV  as a confirmatory test, as used in other studies from Malawi Treponema pallidum hemaglutination assay (TPHA) . Both syphilis tests were conducted according to the manufacturer's instructions. Women were defined as having current or prior syphilis infection if they had positive RPR and TPHA tests.In addition, syphilis tests were conducted in Malawi, for 99 (97%) mothers of cases and for 77 (96%) mothers of controls, using the Rapid Plasma Reagin (RPR) test  and, if positive, confirmed by the p values reported were obtained using two-sided tests of statistical significance.Data were entered into an Access database in Malawi To establish an index of poverty, data on eight proxy markers were combined . Individuals were assigned to one of two groups: those ‘better off’, and those ‘worse off’. The ‘better off’ group were those having either a television, fridge, phone, electricity or piped water, in addition to one or more of the other three markers listed above, while the ‘worse off’ group did not posses any of these five items).Sixty percent of all 148 cases were boys and their ages ranged from 2 years to 15 years (mean age = 7.1 (standard deviation (SD) 2.6 years). Controls were younger (mean age  =  5.1 (SD 3.9 years) and included a slightly smaller percentage of boys (55%) . Almost p = 0.03) (p = 0.02).The percentage of HIV positive children was small for both cases and controls (6% (n = 9) for cases and 2% (n = 2) for controls). However, after adjustment for child's age, sex and residence, cases were 12 times more likely than controls to be HIV positive  . When anptrend<0.001) (p = 0.01) (Sixty percent (n = 77) of HIV negative cases and 21% (n = 19) of HIV negative controls had high EBV antibody levels. ORs for developing Burkitt lymphoma were strongly associated with increasing titers of antibodies against EBV antigens, increasing from 4.1 for those with medium levels, to 14.8 for those with high levels, as compared to those with the lowest levels (d<0.001) . Seventy = 0.01) .p<0.001). Although the data were limited, there was no difference in EBV and malaria antibody levels between HIV negative and positive Burkitt lymphoma cases (data not shown).The joint effects of EBV and malaria antibodies were examined by estimating adjusted ORs for children with raised levels of EBV antibodies only, raised levels of malaria antibodies only, and raised levels of both EBV and malaria antibodies, compared with children with low levels of both . ORs werp = 0.08), while 79% (n = 20) of controls and 57% (n = 17) of cases reported having used them .Questions regarding household mosquito net ownership and use, were introduced eight months after the study began and were, therefore, only available for 30 (20%) of Burkitt lymphoma cases and 25 (24%) of controls . Eighty p = 0.01). Although not statistically significant, 19% (n = 15) of mothers of cases and 7% (n = 4) of mothers of controls reported having children with different biological fathers . The OR was raised for children whose mothers reported more than 1 lifetime sexual partner . Seventy-nine percent (n = 65) of case mothers and 70% (n = 40) of control mothers had high EBV antibody titers . Maternal syphilis status and level of malaria antibodies were not associated with Burkitt lymphoma in the child.Characteristics of 80 HIV negative cases and controls are shown in This case-control study of childhood Burkitt lymphoma in Malawi has focused on the potential role played by three different infectious diseases in children: HIV, EBV and malaria. The positive association between Burkitt lymphoma and HIV found here is similar to that reported from a recent study conducted in Uganda In accordance with results from previous epidemiological studies from sub-Saharan Africa, we have clear evidence to suggest that the risk of Burkitt lymphoma increases with increasing titers of antibodies against EBV in the child In contrast, previous evidence for an association between Burkitt lymphoma and malaria has been largely ecological There is clear evidence from clinical trials that use of bed nets reduces mortality from malaria among children In accordance with the Uganda case-control study That the odds of Burkitt lymphoma increased with the number of children alive reported by mothers may be linked to exposure of the index child to EBV infection and re-infection from other family members It is possible that some case and control children might have been misclassified, 75% of cases and 74% of controls had a histological verification of diagnosis. This is a relatively high rate of verification for an African series In conclusion, this case-control study of Burkitt lymphoma conducted among children in Malawi strengthens the evidence associating the tumor with HIV, EBV and malaria. Improved control of malaria, as well as the future development of EBV vaccines


The decline in malaria coinciding with the introduction of newer, costly anti-malarials has prompted studies into the overtreatment for malaria mostly in East Africa. The study presented here describes prescribing practices for malaria at health facilities in a West African country.Cross-sectional surveys were carried out in two urban Gambian primary health facilities (PHFs) during and outside the malaria transmission season. Facilities were comparable in terms of the staffing compliment and capability to perform slide microscopy. Patients treated for malaria were enrolled after consultations and blood smears collected and read at a reference laboratory. Slide reading results from the PHFs were compared to the reference readings and the proportion of cases treated but with a negative test result at the reference laboratory was determined.Slide requests were made for 33.2% (173) of those enrolled, being more frequent in children (0-15 yrs) than adults during the wet season (p = 0.003). In the same period, requests were commoner in under-fives compared to older children (p = 0.022); however, a positive test result was 4.4 times more likely in the latter group (p = 0.010). Parasitaemia was confirmed for only 4.7% (10/215) and 12.5% (37/297) of patients in the dry and wet seasons, respectively. The negative predictive value of a PHF slide remained above 97% in both seasons.The study provides evidence for considerable overtreatment for malaria in a West African setting comparable to reports from areas with similar low malaria transmission in East Africa. The data suggest that laboratory facilities may be under-used, and that adherence to negative PHF slide results could significantly reduce the degree of overtreatment. The "peak prevalence" in 5-15 year olds may reflect successful implementation of malaria control interventions in under-fives, but point out the need to extend such interventions to older children. In malaria endemic areas, the lack of specific features and adequate laboratory diagnostic facilities often limits the capacity of health workers to establish a definitive diagnosis of malaria. Given the potentially lethal consequences of a missed diagnosis of malaria, case management guidelines had adopted a presumptive approach to treatment for the febrile child in areas considered endemic for disease . Given tPlasmodium infection as assessed by expert slide microscopy [With reports of declining incidence of malaria -10 and ncroscopy . Since tWith declining incidence of malaria, adherence to the reflex to treat any febrile case for malaria is likely to put proportionately more patients at risk of not receiving appropriate treatment. Also, the indiscriminate use of ACT has major cost implications and potentially increases the risk of an emergence of resistance ,23. To aThe bulk of the literature on the subject reports from studies in East Africa in areas with different degrees of malaria transmission. The aim of this study is to provide comparative evidence from a West African country with a distinctly seasonal malaria transmission pattern. The study, therefore, investigated prescription practices immediately following artemether-lumefantrine (AL) introduction as first-line treatment in the Gambia, during and outside of the annual malaria transmission season. The implications of these findings on case management and diagnostic options are discussed.Two cross-sectional surveys were carried out at two primary health facilities (PHFs) serving predominantly urban populations within the Western Division of The Gambia, to coincide with the periods of low transmission (May to July) and peak malaria transmission (August - October) respectively. The study was carried out in 2008 shortly after the introduction of AL into the health system as the first-line treatment for uncomplicated malaria. Both PHFs have laboratory facilities for blood slide microscopy and the outpatient clinics are run by state enrolled nurses trained in the use of the national malaria treatment guideline. The guideline reflects the WHO guideline in identifying symptoms which could indicate malaria and encourages the use of microscopy for diagnosis where available but permits presumptive treatment on the basis of clinical suspicion without a confirmatory test since not all health facilities in the country have supporting laboratories . EligibiP. falciparum was seen on examining 100 high-power fields.Written informed consent was obtained after consultation, and information on presenting complaints, duration of illness, diagnosis made and treatment given were collected onto case report forms. In addition, a finger prick blood sample was collected from each participant for a blood slide and this was read at the Medical Research Council's haematology (reference) laboratory at Fajara. A film was declared negative if no asexual form of The outpatient register used to record attendance and treatments was reviewed to document the total number of people seen and treated for malaria at the PHFs throughout the study period since study recruitment was restricted to working hours on week days only.Studies elsewhere evaluating the proportion of slide negative cases who received anti-malarial treatment have reported values between 62%  in areasMicrosoft Access 2003  was used for double entry, validation and verification of the data. The analysis was carried out using STATA, version 10 . The outcome for the study was the proportion of cases that received anti-malarial treatment, but had a negative blood slide result from the reference laboratory reading. Logistic regression models including age groups , season and interaction terms for age groups and season were performed. Subgroup analysis was carried out for children (<5 and 5-15 years). Sensitivity and specificity of the health centre slide readings compared to the MRC readings was evaluated in the subgroup of patients who had a request for microscopy made at the health facility.The study was approved by the Gambian Government/MRC Joint Ethics Committee.About 8,410 patients were recorded as being treated for malaria at both facilities during the study period; 1,502 in the dry and 6,908 in the wet seasons respectively. A total of 521 patients treated for malaria were enrolled, but analysis was carried out using data for 513 patients; 215 and 298 during the dry and wet seasons respectively (eight entries were excluded due to incomplete data) of those enrolled  season, the highest proportion of positive cases were reported in the age group 5-15 years, with children in that age category being 4.4 times more likely to have a positive result compared to those <5 years old. Also, children within the 5-15 years age group had significantly more positive cases in the wet season compared to the dry season (p = 0.03).The reference slide readings suggest considerably lower parasite prevalence amongst those treated for malaria. Only 9.2% of the 512 patients enrolled and treated for malaria had parasitaemia at the time of diagnosis; 4.7% (10/215) in the dry season and 12.5% (37/297) in the wet season , specificity was significantly higher during the dry season , the increased use of parasitological diagnostics in this age group (for which the IMCI guideline advocated presumptive treatment), may be influenced by more recent local guidelines that promote the use of diagnostics where available. It is conceivable that the recommendation to perform parasitological diagnostics is perceived primarily as an additional layer of measures aimed to improve care in those already identified as risk groups.However, microscopic diagnosis of blood slides from all participants at the reference laboratory show that, among those for whom a slide reading was requested, the highest prevalence of malaria parasites was in 5-15 year old children; these being 3.5 and 13.1 fold more likely to have parasitaemia in the wet and dry seasons respectively than children under the age of five years. To some extent this may be confounded by the fact that care-givers are more likely to bring younger children to the PHF when they are febrile, and that febrile disease due to a variety of causes other than malaria may simply be more prevalent in younger compared to older children. However, a cross sectional survey carried out recently in healthy Gambians similarly identified the peak parasite prevalence occurring in 10-15 year olds . It woulThe most remarkable observation, however, is that in the wet season, 87.5% had no detectable parasitaemia on the reference slide. During the dry season 4.6 times less patients received malaria treatment, but among those, the proportion of unnecessarily administered anti-malarials was even higher, being 95.3%. Several reports from East Africa have recently documented malaria overdiagnosis, and - although only few studies simultaneously measured transmission by means of entomological inoculation rates (EIR) - it appears that overdiagnosis seems to increase as transmission declines. In areas of perennial  and modeIn order to treat patients appropriately and to ensure the sustainability of ACT and to protect the "useful lifespan" of such drug combinations, the new guidelines from WHO recommend that a laboratory test should be performed before treating . TherefoAttempts to step up the capacity of slide reading are likely to be of limited success, as microscopy depends on reliable electricity supply and requires considerable skill and expertise. RDTs in a dipstick format appear to be an attractive alternative for parasitological diagnosis. RDTs do not require particular skills or electricity and can be performed at the point of care by the PHF worker. However, procurement of RDTs is probably only a modest proportion of the cost of integrating RDTs into a health system. The challenges of forecasting RDT needs, managing procurement and distribution through the supply-chain should not be underestimated.Discussions about the best way forward have stimulated a vibrant debate with strong advocacy in favour  and agaiIt is important to note that revised WHO guidelines are not explicit whether or not to withhold anti-malarials from patients where there is a clinical suspicion of malaria but a negative test result. Here, the health care worker's decision depends on his/her trust into the quality of the test and his/her fear of the implications of a missed diagnosis. These situations often result in the half-hearted prescription of an anti-malarial other than the first-line drug .Thus, whether RDTs have the potential to become a cost-effective means to improve the management of febrile cases will depend on successful strategies to promote adherence to the result, and has to overcome the labelling and treatment of all febrile illnesses as "malaria". PHF workers need to be toned to make efforts to consider other, often more difficult to establish, diagnoses and to convince caregivers where a fever has no serious cause.Despite their availability, a consistent pattern of underuse of diagnostic facilities was seen. The proportion of patients likely to receive an anti-malarial for a slide negative result was very high in both seasons. In the context of other published reports this suggests the tendency to overprescribe has increased with recent declines in transmission. While RDT based diagnostic approaches have the potential to be cost-effective, adherence to test results remains its major determinant. Behaviour-change communication campaigns will be needed to encourage withholding of malaria treatment from patients with a negative diagnostic test, thus saving costs without increasing the risk of missing out on the true malaria cases.The authors declare that they have no competing interests.JUO conceived and designed the project, lead the field work, analysed the data and drafted the manuscript; KB and SD helped with the field work and were involved in the review of the manuscript; BW helped with the statistical analysis of the data; DS and DJC provided input into the study design and drafting of the manuscript; MW conceived and designed the project together with JUO, helped with the analysis and drafted the manuscript. All authors read and approved the final manuscript.


Plasmodium vivax is responsible for a significant portion of malaria cases worldwide, especially in Asia and Latin America, where geo-helminthiasis have a high prevalence. Impact of the interaction between vivax malaria and intestinal helminthes has been poorly explored. The objective of this study was to evaluate the influence of intestinal helminthiasis on the concentration of hemoglobin in children with Plasmodium vivax malaria in rural areas in the municipality of Careiro, in the Western Brazilian Amazon.P. vivax malaria. For 54 schoolchildren with a single infection by P. vivax, hemoglobin during the malaria episode was similar to the baseline hemoglobin for children co-infected with Ascaris lumbricoides (n = 18), hookworm (n = 11) and Trichuris trichiura (n = 9). In children without intestinal helminthes, a significant decrease in the hemoglobin during the malarial attack was seen as compared to the baseline concentration. In the survival analysis, no difference was seen in the time (in days) from the baseline cross-sectional to the first malarial infection, between parasitized and non-parasitized children.A cohort study was conducted from April to November 2008, enrolling children from 5 to 14 years old in two rural areas endemic for malaria. A cross-sectional evaluation was performed in April to actively detect cases of malaria and document baseline hemoglobin and nutritional status. Children were followed-up for six months through passive case detection of malaria based on light microscopy. Throughout the follow-up interval, hemoglobin value and stool examination  were performed on children who developed P. vivax.For the first time, a cohort study showed that intestinal helminthes protect against hemoglobin decrease during an acute malarial attack by  Plasmodium vivax. In this same period, 3,833,477 cases were reported in Brazil, mainly in the Amazon Region, with the same predominance of P. vivax (76.7%) Malaria is one of the most important public health problems in the world, with 3.3 billion people at risk of contracting the disease and almost one million deaths annually, mainly in children under five years Malaria contributes to hemoglobin concentration decrease through a number of mechanisms, primarily through destruction and removal of parasitized erythrocytes, and a decrease in the average life span and rate of production of red blood cells Ascaris lumbricoides, hookworm and Trichuris trichiura. These are widely distributed in tropical countries, infecting 1.3, 1.4 and 1 billion people, respectively Trichuris trichiuraAscaris lumbricoides influences the nutritional status In Brazil, especially in the Amazon region, geo-helminthiasis have a high prevalence P. falciparum among those co-infected with intestinal helminthes In the Amazon region, as in many other parts of the world, endemic areas for malaria coincide with locations of high prevalence of intestinal helminthiasis P. falciparumP. vivax is responsible for a significant portion of malaria cases worldwide, especially in Asia and Latin America Research on the interaction between these parasites is predominantly focused on P. vivax malaria in rural areas highly endemic for malaria, in the Western Brazilian Amazon.The objective of this study was to evaluate the influence of intestinal helminthiasis on the hemoglobin concentration in children with The study was approved by the Ethical Review Board of the Tropical Medicine Foundation of Amazonas . Parents' participants were instructed about the objectives of the study and signed an informed consent. Patients diagnosed with intestinal parasites and malaria were treated according to the guidelines of this institution.2 and 31,063 inhabitants. The climate is tropical and humid, with rainfall ranging from 2,100 to 2,400mm per annum. The municipality is connected with the capital of the state, Manaus, through a federal road (112 km of distance).A cohort study was carried out in two schools located in two recently colonized areas devoted to agriculture (Panelão and Céu Azul Communities), from April to November 2008. These settlements are located in the Municipality of Careiro, Amazonas State. The municipality has an area of 6,124.30 kmThe total population of both communities is 790 persons, according to the census performed before the beginning of the study. The major economical activities are family farming, hunting and fishing. Water for drinking comes from rain water reservoirs or creeks. Garbage collection and sanitation are absent. Two health agents in each community are responsible for health care.The studied population was composed of 236 schoolchildren 5 to 14 years old.P. vivax infection had a stool examination and hemoglobin concentration performed on the day of the diagnosis. After the first malarial episode, the child was not subsequently followed. Children diagnosed with P. falciparum or mixed infection , or those who had received anti-helminthic drugs during the study interval, those who could not collect three samples of feces on alternate days, or those who declined to participate in the study were excluded from the analysis. To eliminate potential confounding factors, patients with known hemoglobinopathies, glucose 6-phosphate dehydrogenase deficiency, and/or other chronic diseases were excluded.In April 2008, a cross-sectional study was conducted to actively detect malaria cases or asymptomatic Plasmodium carriers, establish baseline hemoglobin, assess nutritional status. Children who had a positive thick blood smear were treated according to the Brazilian Anti-Malarial Treatment Guidelines and not included in the analysis afterwards. Children were followed from April to November 2008, and when presented with measured or reported history of fever, a thick blood smear was performed (passive case detection). In this period, children who developed the first episode of 3 for each child. Parasitemia was quantified as asexual parasites/mm3.Thick blood smear was prepared as recommended by the Walker technique Weight and height were obtained by internationally recommended methods, as follows. Weight was measured by use of a digital scale and height was assessed with the help of a tape. Body Mass Index (BMI) was calculated using the program EPI-INFO 3.4.3. BMI Z-score <−2 was defined as malnutrition, scores between −2 and Z<−1 as the risk zone; Z score between −1 and 2 normal weight and Z score >2 as obesity Ascaris lumbricoides and Trichuris trichiura was performed by examination of three samples of stool from each child, collected on alternate days. A single researcher performed all the exams, in order to avoid examiner's bias. The stool samples were stored in flasks containing 10% formalin as preservative. Flasks were labeled with the patient's name, date of collection and kept at room temperature until the end of the month, when all the stool samples were examined. Spontaneous sedimentation The search for hookworm, Hemoglobin concentration was measured in venous blood obtained from digital puncture, using a portable HemoCue® photometer .Data were analyzed using SPSS® version 16.0 for Windows . Normal distribution of data was evaluated with the Kolmogorov-Smirnov test. Chi-square or Fisher's test was used to test differences in proportions, and Student t test was used to test differences in means. Non-parametric Spearman's test was used for the correlation analyses. A Kaplan-Meier survival analysis was performed in order to detect differences in the time elapsed from the baseline cross-sectional to the first malarial episode between children with and without intestinal helminthes. Log-rank test was used to test differences. Statistical significance was considered if p<0.05.During the six-month follow-up interval, from 236 eligible children, 216 were enrolled in the cohort, as seen in the algorithm in Trichuris trichiura had mothers with a significantly higher level of education as compared to the non-parasitized.In P. vivax attack in children co-infected with Ascaris lumbricoides (p = 0.221), hookworm (p = 0.353) and Trichuris trichiura (p = 0.976). For schoolchildren with P. vivax infection without these helminthes at stool examination, the mean of hemoglobin during the acute malarial attack was significantly lower than the mean of the baseline hemoglobin for all the helminths (p<0.005).No child required hospitalization in the local hospital or died during the course of the study, and no iron supplementation was prescribed.Anemia is widely distributed and often found in developing countries P. vivax predominates and malnutrition is not as frequent and severe as on the African Continent.Although the etiology of anemia is complex and multifactorial, parasitic diseases, including malaria and intestinal parasites are recognized as the major cause of anemia in endemic countries P. vivax malaria. Previous studies have shown that helminth infections provide protection against infection by P. falciparumA. lumbricoides was associated with biological suppression of malaria A. lumbricoides promotes a protective effect against cerebral malaria P. falciparum malaria had lower mean of admission temperatures than patients without hookworm P. vivax infection would not be appropriate in our field study, in an unstable transmission area, where no child needed hospitalization or died during the course of the study. Further studies are needed focusing in patients from tertiary care centers, where clinical severity is more common This study demonstrated that intestinal helminthiasis is associated with protection against a decline in hemoglobin concentration during episodes of A. lumbricoides is associated with lower parasitemia in P. falciparum malaria S. mansoniA. lumbricoides infection and severe malaria was found elsewhere, despite of the loose definition of severity in this particular case P. falciparumP. vivax was not different between children with and without helminthiasis. This is probably because they were diagnosed very early (diagnostic tests are available for everyone at no cost in the community) and also because P. vivax lacks the development of high parasitemia due to its selective reticulocyte invasion. In children with severe falciparum malaria, co-infection with helminthes leaded to the decrease in circulating reticulocyte counts P. vivax-triggered anemia through the reduction of reticulocytes, although this issue was not addressed in our study. The presence of helminthes contributed to a lack of association between parasitemia and hemoglobin in this group, suggesting that helminthes may modulate the impact of parasitemia upon anemia. Recently, it was shown that the frequency of CD4+CD25+FoxP3+ regulatory T cells correlates with P. vivax parasitemia in vitro for P. falciparumP. falciparum infection or mixed infection  were not analyzed as a comparator group due to the small number of cases. An active case detection design  could additionally identify if intestinal helminths are able to confer protection against the clinical manifestations of the disease and/or the state of asymptomatic carrier of the parasite.The influence of helminthic infections on malaria is not entirely straightforward. In Madagascar, it was observed that infection by P. vivax infection is mostly seen in children under 5 years of age Despite evidence that malaria/intestinal helminthiasis co-infection increases the risk of anemia, little is known about the impact of co-infection on anemia amongst different age groups per se, we expected that in this group anemia would be more severe. However, it is important to note that in all the groups children sometimes had more than one helminth at stool examination, precluding an isolated analysis. Due to the lack of a professional who could perform the Kato-Katz technique in the field to quantify the intestinal helminth load in fresh stool, we could not evaluate for the potential effects of intensity of helminth infection. Further studies should explore this aspect.Surprisingly, not even hookworm infection was associated with a decrease in the hemoglobin concentration in children with malaria. Due to the anemic effect of this helminth P. vivax clinical protection.A clear bias of this study could have been the longer time elapsed from the baseline cross-sectional until the first malarial episode in children without intestinal helminthes, subjected therefore to other determinants of anemia. However, for every studied helminth, this time was very similar, what additionally suggests that intestinal helminthes do not contribute to P. vivax. To our knowledge, this is the first report to demonstrate the impact of helminthic co-infection on a complication triggered by P. vivax, based on a cohort study. The mechanism by which helminthes apparently protect against a decrease in hemoglobin in vivax malaria is unknown. One speculates that high levels of the Th2 cytokines (IL-10) during helminth infection counteract the Th1 cytokines (TNF) induced by malaria to prevent the development of severe anemia P. vivax infection.It was noted that helminthes protect against the reduction of hemoglobin during acute malarial attacks by


Effective and timely case management remains one of the fundamental pillars for control of malaria. Tanzania introduced artemisinin-combination therapy [ACT] for uncomplicated malaria; however, the policy change is challenged by limited availability of ACTs due to high cost. This study aimed to determine factors influencing prompt access to ACTs among febrile children in rural Kilosa, Tanzania.In a community-based study, 1,235 randomly selected children under five were followed up weekly for six months, in 2008. Using a structured questionnaire, children's caretakers were asked about the child's febrile history in the last seven days, and treatment actions including timing, medicines used and source of care. Caretakers' knowledge about malaria and socioeconomic and demographic data were also obtained. About half of followed-up children had at least one episode of fever. Less than half (44.8%) of febrile children were taken to government facilities. Almost one-third  of febrile children had prompt access to ACT. Care-seeking from a government facility was the overriding factor, increasing the likelihood of prompt access to an ACT 18 times . Caretakers from the better-off household (3rd–5th quintiles) were more likely to seek care from government facilities . The majority of antimalarials accessed by the poor were ineffective , however, they paid more for them (median Tsh 500) compared to the better-offs (median Tsh 0).Prompt access to ACT among febrile children was unacceptably low, due mainly to limited availability of subsidised ACT at the location where most caretakers sought care. There is urgent need to accelerate implementation of strategies that will ensure availability of ACT at an affordable price in remote rural areas, where the burden of malaria is highest. Effective malaria case management, that is, early diagnosis and prompt treatment of malaria patients, remain to be one of the fundamental pillars of malaria control measures. The current advocated global targets include achievement, by 2010, of universal coverage of all malaria patients diagnosed and treated with effective antimalarial medicines within one day of the onset of illness In Tanzania, malaria which is the leading cause of morbidity and mortality accounts for over 40% of out-patient attendances and 36% of all death in under fives . Tanzania accommodated the malaria treatment policy change for uncomplicated malaria from sulphadoxine-pyrimethamine (SP) to ACT in October 2006 . However, procurement of ACT is mainly through the support of funding from the Global Fund to Fight AIDS, Tuberculosis and Malaria and caters for ACT provision by government and not-for-profit private health facilities, which include Faith Based Organisation [FBO] facilities. In the former, free services are provided to under-fives, whereas in the latter, a considerable fee is charged, even if the ACT is free. Furthermore, most treatment for malaria is provided outside the formal healthcare sector, usually by shopkeepers where treatment is often inappropriate A recent Malaria Indicator Surveys (MIS) conducted in Tanzania revealed that only 13% of the febrile children had prompt access to the ACT . Studies conducted prior to ACT era indicated availability of medicines, source of care, perceptions about causes and the severity of illness, the efficacy of treatment, the ability to pay, and the distance to the health facility as factors influencing timely access to malaria treatment Kilosa district is situated about 300 kilometres west of Dar es Salaam, the largest business city in Tanzania. The district has about 488,000 people, of which 79,000 are under five years . Administratively, the district has seven divisions with 161 registered villages and is divided into four geographic-climatic areas: wet-highland, dry-highland, wet-lowland and dry-lowland . The district has an under-five mortality of 166 per 1,000, and about 32% of the people live below the poverty line . The main sources of income are farming and livestock keeping. Food crops produced at subsistence level are maize (staple food), cassava, rice and sorghum. In 2007, malaria accounted for more than half [55.5%] of the total outpatient attendance, and 60% of the total deaths among under-fives admitted to the hospitals . Malaria transmission in the wet-lowland area occurs throughout the year, with the highest incidence during and soon after the rain season, March to June.Kilosa has 71 health facilities, comprised of 3 hospitals, 7 health centres and 61 dispensaries . Of these, two hospitals, one health centre and nine dispensaries belong to FBOs, and charge a fee for consultation, drugs and laboratory tests. In the public facilities, services for under-fives are offered free of charge. There were 152 drug shops in the district, most of them found in urban and semi-urban areas. At the time of the study, about 92 drug shops met the minimum criteria set by the Tanzania Food and Drug Agency (TFDA) and were upgraded to the status of ADDO, which allowed them to sell artemether-lumefantrine (ALu). ADDOs are able to purchase ALu at a subsidised price and charge a flat rate of US $0.50 for one paediatric treatment course .This is a prospective study design, in which 1,200 randomly selected children aged 3–59 months were followed up at their homes weekly for six months, in 2008. Weekly follow ups were chosen so as to maximize recall of events. The outcome measure was prompt access to ACT among children who had fever episode as reported by the caretaker. Fever was used as a proxy for malaria given the absence in rural areas of laboratory facilities for diagnosing malaria and the national treatment guidelines that advised treating childhood fevers suspected to be malaria with the recommended first-line treatment. This proved for us to be of practical use as reported by other researchers Stratified random sampling was performed by dividing rural villages into the four geographic-climatic areas, wet-highland, dry-highland, wet-lowland and dry-lowland, using a list of villages from the national census. In each area, one village was randomly selected from among villages with health facilities, and two from those without, making a total of 12 villages. Under-five children were randomly selected from village registers. Village registers are kept by the Village Executive Officer in all villages within the country. However, in many villages these registers were not up-to-date. Therefore, village registers had to be updated by the researchers with the assistance from the village health workers (VHWs) via house-to-house visits. A sample size of 1,200 was thereby apportioned to the 12 villages, according to village population size and random selection was performed using EPI-INFO, software (version 6). The sample size was derived by requiring a maximum length of 95% confidence interval +/−5% units, and assumed a proportion of 50%. Adding 10% for possible loss to follow-up, and 38% correction factor for clustering effect on village level [ICC = 0.01], the total sample size came to 583 (approximated to 600). Available data reported by patients/caretakers indicated that the 2-week period incidence of fever suspected to be due to malaria in Tanzania was 6% Two to four VHWs were recruited in each village, depending on the village size. These were centrally trained for six days on the purpose of the study, data collection procedures and ethical issues. Three research assistants dawa mseto) were obtained from caretaker's report. Children, who had not recovered at the time of the interview, completed their information on what happened after the previous encounter during the next round. Children found to have severe symptoms on the day of interview were advised to be taken immediately to the health facility.Baseline and follow-up questionnaires were developed based on previous literature In government health facilities, medical notes are written in notebooks and are kept by caretakers. These, as well as drug containers, were examined to verify the type of drug provided. Where such evidence was not available, verification was performed by displaying samples of locally available brands Data were double entered into EpiData 3.0  and analysed using STATA version 10.1 . The outcome measure was ‘prompt access to ACT’ which was defined as treatment with any type of ACT on the same or the next day of fever onset malaria ya kawaida) and knowledge about the causes of convulsion to children. The total number of people in the household and all individual symptoms except cough were found not statistically significant. The rest of the variables were introduced in a stepwise analysis multiple regression model where only the source of care and knowledge on the recommended drug for the treatment of uncomplicated malaria were retained in the final model. In determining factors influencing care-seeking from government health facilities the same variables used in the previous model were analysed. Failure to feed, cough, SES and knowledge of treatment for uncomplicated malaria and knowledge about the cause of convulsions were found to be statistically significant. These were introduced in a stepwise regression model and all variables except cough and knowledge on cause of convulsion were retained in the final model.Bivariate analysis was performed on variables likely to influence the prompt access to the ACT as well as the source of care. All variables that were found to have a statistically significant association were introduced into the multiple regression models using stepwise analysis, with a cut-off point of 0.10. All regression analysis were weighted. Post-stratification weighting was done at the strata level  after observing that the sampling proportion did not perfectly match the true distribution of the population. Odds ratios [OR] with 95% confidence intervals [CI] were used to measure association. Significance was tested at the 5% level. Variables introduced in the multiple regression model to determine an association of prompt access to the ACT were the total number of people in the household, number of under fives, the source of care, severe symptoms , separate individual symptoms, SES, knowledge on the recommended drug for the treatment of uncomplicated malaria , Tanzania. Permission to conduct the study was also obtained from the regional and district authorities. A written informed consent was obtained from each adult caretaker of the child during baseline data collection.During the six-month collection period, 35 children were added to the enrolment after children, who had either attained the age of 60 months or who were reported to have migrated during the study period, were replaced by random selection. In all, 1,235 children aged 3–59 months were enrolled. There was no difference between febrile and non-febrile children in relation to the socio-demographic characteristics of the children and their caretakers . The medOut of the 607 children with fever, 264  were taken to government health facilities for care in the course of their illness . No carerd–5th quintiles) were more likely to receive ALu  compared to the poor , .Of the 607 children, 374  received antimalarials, of which, 268  were ACT, and all were ALu. The majority of those who were taken to government health facilities were treated with ALu , while only 14.0% (48/343) of those who were taken to the other facilities received ALu. Children from the better-off household (3The average expenditure on drugs reported by caretakers was Tanzanian shillings (Tsh) 767 , and the median was Tsh 200 . The median expenditure on drugs at government health facilities was zero. Within the private sector, the median expenditure on drugs was highest among FBO facilities  followed by ADDO  and drug shops (Tsh 900). Median expenditure was least at ordinary shops (Tsh 500). Caretakers from the poor households paid more compared to the better-offs, median expenditure Tsh 500 and zero, respectively.Overall, 223 of 607  of the children who had fever received ALu promptly. Prompt access to the ACT was higher  among children taken to the government health facilities compared to those taken elsewhere , see awa mseto (Coartem®) is the recommended drug for the treatment of malaria ya kawaida [uncomplicated malaria] influenced prompt access to ACT. Together, the two factors explained for 30% of the variability. Seeking care from a government health facility and knowledge that dmalaria ya kawaida) were 8-times more likely to access the ACT promptly  compared to those who did not have the knowledge, see Further analysis by geographic-climatic strata showed a similar pattern with regard to the source of care, except in the wet-highland stratum where the association was less remarkable  . In the Dawa mseto) is the recommended drug for the treatment of uncomplicated malaria , were more likely to take their children to a government health facility compared to those who did not know . Knowledge about mosquitoes, and that high fever causes convulsion in children, increased the likelihood of taking a child to a government health facility in dry-highland areas; however, the difference was not significant .Since seeking care from a government health facility was the main factor associated with prompt access to the ACT, further analyses was done to determine factors that influence seeking care from these facilities. Children from the better-off households were twice more likely to be taken to a government health facility compared to those from poor households . Moreover, the better-offs were found to live closer to government health facilities  compared to the poor . Further analysis showed that the better-offs were 4-times more likely to have knowledge on the recommended drug for treatment of uncomplicated malaria , and that they were more likely (2.5-times) to own radios compared to the poor .This study shows that nearly two-third of the children with fever received antimalarials on the same or next day of the onset of fever, of which less than half were ALu. Furthermore, only one-third of the children had prompt access to the ACT, and that seeking care from government health facilities was the major determining factor. The study has also shown that, despite subsidy on ACT, the poor were paying more, as compared to the better-offs, for the ineffective drugs they got from non-government facilities simply because they had less access to government health facilities. Previous studies have also reported source of care as one of several factors influencing access to antimalarials Encouragingly, prompt access to the ACT was very high among children taken to government health facilities, in this study. However, the fact that less than half of these children were taken there, raises some pertinent questions as to why most caretakers did not seek care from government health facilities where the ACT was provided free of charge. This can be explained by the findings from previous studies that reported caretakers residing closer to a government health facility were more likely to seek care from these facilities The majority of caretakers who did not seek care from government health facilities were from the poor households, this confirms the ‘inverse care law’ stating that “the availability of good medical care tends to vary inversely with the need for the population served” Subsidy has made ALu quite cheaper thus affordable to many people. But despite the subsidy, prompt access to the drug was very low among children taken to FBO facilities and ADDOs. Most of the FBO facilities are situated in rural remote areas and serve poor communities. Unfortunately, they charge a considerable fee to cover operating costs Knowledge that ALu is the recommended drug for the treatment of uncomplicated malaria was associated with increased prompt access to the ACT in the wet-lowland areas, where malaria transmission is high and occurs throughout the year. This might be an indication of the successful advocacy campaign by the National Malaria Control Programme. Radio and television adverts and programmes featuring ALu as the recommended first-line drug have been aired since the inception of the new drug policy. Such messages might have been taken more seriously in areas where malaria transmission is intense. The lack of association between SES and prompt access to the ACT found in this study might be due to the overwhelming influence of the source of care which might have concealed the influence of poverty on prompt access.Diagnosis of malaria relied on caretaker's report of fever. This might result in underestimation of prompt access to the ACT since not all fevers are due to malaria. However, the fact that Kilosa is hyperendemic area increases the likelihood of most fevers to be due malaria. Underestimation of prompt access might also have resulted from including children who were suspected to have severe malaria and were correctly treated with the second line antimalarials, or from children who were found to have a negative blood slide for malaria parasites and were treated with other drugs Ascertainment of the drug given to a child can be difficult, especially if the caretaker does not know how to read and write. Therefore samples of the drug packets and records from the clinician or drug shop were used to verify the type of drug given The use of village health workers with low level of basic education might have undermined data quality. However, given the one-week training prior to data collection, the day-to-day close supervision by RAs and the weekly meetings, the problem of data quality might have been minimized. Further, the presence of village health workers might have caused a ‘Hawthorn effect’ likely to overstate the level of prompt access to the ACT.Findings from strata analysis should be interpreted with caution because the sample size for this study was calculated to power the overall analysis and not the strata specific analysis.The major drawback to promptly accessing ACTs found in this study was the limited availability of subsidized ACT in places where most caretakers took their children for care. And despite subsidy on the ACT, a majority of caretakers, especially from the poor households, continue to pay more for ineffective drugs in non-government facilities.Government health facilities proved to be the best source for accessing prompt treatment, as judged by the highest rate of prompt access to ACTs. Therefore, greater part of the global effort on malaria should focus on strengthening the public sector. However, government health facilities were accessed mostly by the relatively wealthy. Therefore, access to government health facilities need to be improved by optimizing the location of health facilities - nearer the malaria hotspots. In the non-government sector, merely subsidizing the price of ACT is insufficient. In addition to the subsidy, the quality of services must be regulated to provide the recommended treatment. Furthermore, information must be provided effectively to the poor on the best treatment and their sources. Further research should address why prompt access to ACT in ADDOs and FBOs is low despite ACT subsidy, and how FBO facilities, located mostly in remote rural areas, can be maximally utilised to reach the marginalized children.


Ethiopia plans to increase its electricity power supply by five-fold over the next five years to fulfill the needs of its people and support the economic growth based on large hydropower dams. Building large dams for hydropower generation may increase the transmission of malaria since they transform ecosystems and create new vector breeding habitats. The aim of this study was to assess the effects of Gilgel-Gibe hydroelectric dam in Ethiopia on malaria transmission and changing levels of prevalence in children.A cross-sectional, community-based study was carried out between October and December 2005 in Jimma Zone, south-western Ethiopia, among children under 10 years of age living in three 'at-risk' villages (within 3 km from dam) and three 'control' villages (5 to 8 km from dam). The man-made Gilgel-Gibe dam is operating since 2004. Households with children less than 10 years of age were selected and children from the selected households were sampled from all the six villages. This included 1,081 children from 'at-risk' villages and 774 children from 'control' villages. Blood samples collected from children using finger prick were examined microscopically to determine malaria prevalence, density of parasitaemia and identify malarial parasite species.Plasmodium vivax, 76 (39.2%) for Plasmodium falciparum and one (0.5%) for both P. vivax and P. falciparum. A multivariate design-based analysis indicated that, while controlling for age, sex and time of data collection, children who resided in 'at-risk' villages close to the dam were more likely to have P. vivax infection than children who resided farther away (odds ratio (OR) = 1.63, 95% CI = 1.15, 2.32) and showed a higher OR to have P. falciparum infection than children who resided in 'control' villages, but this was not significant . A classification tree revealed insights in the importance of the dam as a risk factor for malaria. Assuming that the relationship between the dam and malaria is causal, 43% of the malaria occurring in children was due to living in close proximity to the dam.Overall 1,855 children (905 girls and 950 boys) were surveyed. A total of 194 (10.5%) children were positive for malaria, of which, 117 (60.3%) for This study indicates that children living in close proximity to a man-made reservoir in Ethiopia are at higher risk of malaria compared to those living farther away. It is recommended that sound prevention and control programme be designed and implemented around the reservoir to reduce the prevalence of malaria. In this respect, in localities near large dams, health impact assessment through periodic survey of potential vectors and periodic medical screening is warranted. Moreover, strategies to mitigate predicted negative health outcomes should be integral parts in the preparation, construction and operational phases of future water resource development and management projects. Malaria is one of the most important causes of morbidity and mortality in tropical and sub-tropical countries. It is responsible for more than one million deaths each year . The estMalaria transmission varies among communities largely due to environmental factors, such as proximity to breeding sites . Many waIn Ethiopia, approximately 75% of the total area is estimated to be malarious, with 68% of the total population (52 million people) being at risk of infection . AccordiAnopheles ranges from 0.8 km (An. funestus) [An. gambiae s.s) [Gilgel-Gibe hydroelectric dam, created by impounding the water of the Gilgel-Gibe River in south-western Ethiopia, is currently the largest supply of power (184 MW) in Ethiopia and is operating since 2004. During the construction of the dam, many people were relocated upstream of the reservoir, although some still remain close to the buffer zone (500–800 m from the reservoir edge at full supply level) surrounding the lake. The location of the rural villages near the newly formed reservoir may increase malaria transmission, assuming that this reservoir contributes directly or indirectly to the presence of breeding places for malaria vectors. Studies in various African countries indicate that the flight range of different species of unestus)  to an aviae s.s) , and theiae s.s) -29.The current study investigates the possible effects of Gilgel-Gibe hydroelectric dam on malaria transmission and prevalence among children below the age of 10 years, focusing on the distribution of infection in relation to distance of villages from the reservoir shore. Results may further guide the development of appropriate malaria interventions for communities living around the reservoir.weredas) and have similar settlement pattern, have access to health services and are socio-economically similar. Census results taken between August and September 2005 showed a population of 6,985 in the study villages. All the communities residing in the study villages belong to the Oromo ethnic group, which is one of the largest ethnic groups in Ethiopia. The reservoir covers an area of 62 km2 and is located at an altitude of 1,671 m. There are no other permanent water bodies or impoundments other than the reservoir found around the six study villages.The study area is located 260 km south-west of the capital, Addis Ababa in Oromia Regional State, south-western Ethiopia near Gilgel-Gibe hydroelectric dam. The study area lies between latitudes 7°42'50"N and 07°53'50"N and between longitudes 37°11'22"E and 37°20'36"E, at an altitude of 1,734–1,864 m above sea level. The area has a sub-humid, warm to hot climate, receives between 1,300 and 1,800 mm of annual rainfall and has a mean annual temperature of 19°C. The main socio-economic activities of the local communities are mixed farming involving the cultivation of staple crops , and cattle and small stock raising. The study villages are located in Omo-Nada, Kersa and Tiro-Afeta districts  and three villages located 5–8 km from its shore  were randomly selected and designated as 'at-risk' and 'control' villages, respectively. The selection of 'at-risk' and 'control' villages was based on the established flight range of anopheline vector mosquitoes as described elsewhere in this paper -29. 1, 8Plasmodium species were performed as per standard methods [Plasmodium species. The initial thick films were considered negative if no parasites were seen in at least 100 oil-immersion fields of the thick film [Plasmodium positive children were treated according to the national malaria treatment guideline of the Government of Ethiopia [A parasitological study was carried out for three months (October-December 2005) to investigate the difference in malaria prevalence between 'at-risk' and 'control' villages and to characterize malaria in the area. During the survey, socio-demographic data were collected and house-to-house visits were made each month to collect blood samples from every child less than 10 years of age and thick and thin films were prepared directly from finger prick blood samples. Blood sample collection, preparation, staining technique and microscopic identification of  methods . The thiick film . For posick film . All PlaEthiopia .Plasmodium falciparum and Plasmodium vivax was calculated across age, village of residence and month of infection. Logistic regressions were conducted to check for any significant differences in the proportions of malaria cases between 'at-risk' and 'control' communities both in a univariate manner and controlling for age, sex and month. The clustering at village level was taken into account in the logistic regression models (univariate as well as multivariate) by using a marginal model with the Taylor series linearization method for estimating the variances.Data were entered in and analysed with the statistical programme STATA 10 software package . Prevalence rates were calculated from monthly positive cases. The prevalence of To investigate the potential complex interactions between the different determinants in explaining the presence of the parasite, classification trees (CART) were used . This teThe cross-sectional study allows to compute a prevalence ratio (PR) which is computed as follows: p(D+|E+)/p(D+|E-) with p a probability, D+: positive case, E+: living close to the dam and E-: living away from the dam. The 'prevalence fraction (exposed)' was calculated using the relation that PrFe = (PR-1)/PR. The PrFe expresses the proportion of disease in exposed individuals that is due to the exposure, assuming that the relationship is causal. Alternatively, the indicator can be viewed as the proportion of infections in the exposed group that would be avoided if the exposure were removed.Ethical approval for this study was obtained from Jimma University Research and Ethics Committee. Communal consent was first obtained then children were recruited after informed oral consent was sought from their parents or guardians of each child before a child was enrolled in the study.P. vivax, 76 (39.2%) for P. falciparum and one (0.5%) for both P. vivax and P. falciparum.Of the 1,855 children below the age of 10 years examined in this study, 905 (48.8%) were girls and 950 (51.2%) were boys. The mean age of children was 4.7 years and the number of children surveyed from 'at-risk' and 'control' communities was 1,081 (58.3%) and 774 (41.7%), respectively. Of the children in 'at-risk' communities, 528 (48.8%) were boys and 553 (51.2%) girls while in 'control' communities, 377 (48.7%) were boys and 397 (51.3%) were girls. Overall, 194 (10.5%) of the sampled children were positive for malaria, of which, 117 (60.3%) were positive for P. vivax (60.7%) and P. falciparum (57.9%) positivity rates were observed in October. The P. vivax prevalence varied from 5.9% in children <1 year of age to 6.4% in those 5–9 years of age. The P. falciparum prevalence varied from 4.2% in children <1 year of age to 3.8% in those 5–9 years of age.Highest P. vivax point prevalence during the three months ranged from 0.8% to 10.0% and form 2.3% to 5.9% in 'at-risk' and 'control' villages, respectively. Monthly P. falciparum point prevalence during the three months ranged from 2.7% to 6.9% and from 1.2% to 4.0% in 'at-risk' and 'control' villages, respectively  and the P. falciparum prevalence was significantly higher in 'at-risk' communities in December   were obvious and statistically significant in all months (p < 0.01).The P. vivax and OR = 2.57, 95% CI = 1.01, 6.57 for P. falciparum)  and P. falciparum prevalence rates differed significantly between 'at risk' and 'control' communities among 5–9 years of age .In general, significantly higher malaria prevalence was observed in children living within 3 km from the reservoir than those living farther away  . The multivariate analysis indicated that, while controlling for age, sex and time of data collection, children who resided in 'at-risk' villages close to the dam had a higher OR to have P. falciparum infection than children who resided in 'control' villages but this was not significant at the 0.05 level . Finally, while controlling for age, sex and time of data collection, children who resided in 'at-risk' villages close to the dam were at a higher risk to have a Plasmodium infection  than children who resided in 'control' villages   and those sampled in October-November . The group of children sampled in October-November was further split in children living in 'at-risk' communities  and those living in 'control' communities . The group of children living in 'control' communities was further split in children of age below 5 years  and above 5 years . According to the overall discriminatory power (i.e. the relative importance) in the CART analysis, month emerged as the strongest overall discriminating risk factor for a P. vivax infection (Score (Sc) = 100), followed by village type (Sc = 20.21) and age (Sc = 8.73) and sex (Sc = 2.19). The classification tree corresponds well with the P. vivax trends in Figure P. vivax prevalences in 'at-risk' and 'control' communities are both low and that the difference between 'at-risk' and 'control' communities are especially clear in October-November.Figure P. falciparum reproduced by CART. Children are first split into children living in 'at-risk' communities  and those living in 'control' communities . The group of children living in 'at-risk' communities was further split in children sampled in November  and those sampled in October and December . According to the overall discriminatory power in the CART analysis, village type emerged as the strongest overall discriminating risk factor for malaria P. falciparum infection (Sc = 100), followed by month (Sc = 41.3). The other variables, age and sex had a zero-Score. The classification tree corresponds well with the P. falciparum trends in Figure falciparum prevalences are lower in 'control' communities and that in 'at- risk' communities the prevalences were lower in November.Figure ion Sc = 00, folloP. vivax and P. falciparum together), measuring the effect of the dam, was calculated using prevalence ratio p(D+|E+)/p(D+|E-) = 7.7/4.4 = 1.75 and is PrFe = (PR-1)/PR. = 0.43. This means that 43% of the malaria occurring in children can be attributed to the dam, assuming that the relationship is causal.The 'prevalence fraction (exposed)' PrFe, for malaria (P. vivax (7.7%) in children who reside with in 3 km of the reservoir created by the Gilge-Gibe hydroelectric dam was significantly higher than in children living in more distant villages (4.4%) although the villages have a similar eco-topography. Plasmodium falciparum prevalence rates in 'at-risk' communities (5.4%) were higher than in 'control' communities (2.2%), but the difference showed no statistical significance . Overall, the Plasmodium prevalence near the reservoir was statistically higher as compared to the Plasmodium prevalence in more distant communities . The main reason for the higher prevalence of malaria among children living close to the reservoir may be due to the man-made ecological transformations, which may influence the presence of mosquito-breeding site and might have an impact on the behaviour, parity rate and longevity of malaria vectors of the study area. A similar study in Cameroon showed a malaria prevalence of 36% in residents living in close proximity to a man-made lake compared with a prevalence of 25% in a village 14 km away [In this study, after controlling for age, sex and time, the prevalence of  km away . A high  km away . Risk faP. vivax and P. falciparum together). This could be because the older children, in contrast to younger children, spend outdoors in the evening when peak biting activities of malaria vector mosquitoes are high or the greater use of anti-malarial drugs in early childhood [Plasmodium prevalence rates in children between one and four years, below one year and children age of 5–9 years showed no statistically significant differences.This study indicates that children between the age of one and four years tend to have a higher malaria prevalence than children below the age of one year  children, P. falciparum in 76 (39.2%) and mixed infection in one (0.5%) child. The other two Plasmodium species, P. malariae and P. ovale were absent. A similar distribution  was reported in a previous study [et al [P. falciparum during October while P. vivax tends to dominate during November. A parasitological community-based study conducted by Gebreyesus et al [P. falciparum. The prevalence of malaria infections varies seasonally, with P. vivax dominating in the dry season (March-June) and P. falciparum peaking in September-October, after the end of the main rainy season [et al [P. vivax and 40.9%–73.4% of P. falciparum) during different seasons.According to several reviews, ectively ,41. In tus study . But, iny [et al  reportedus et al  on the iy season . Hence, n [et al  reportedet al [P. vivax, children can be grouped according to month and children sampled in October-November showed higher prevalences even more when children were living in 'at-risk' communities . For P. falciparum, the children living in 'at-risk' communities were grouped together because of higher prevalences. Within 'at-risk' communities especially children sampled in October and December showed a higher prevalence of 6.3%.The classification trees show that using this non-parametric technique allows obtaining a better insight in the data structure and the available interactions between determinants in their influence on (or relation with) malaria. This was also noted by Thang et al . The claPlasmodium infection than children living further away, possibly due to the creation of new vector habitats around the lakeshore. Epidemiological studies focusing on vector dynamics and socioeconomic, demographic and health behaviour factors could be conducted to identify underlying causes of the spatial pattern of infection reported in this paper.In conclusion, this study informs that children living in close proximity to the reservoir created by the newly constructed Gilgel-Gibe dam are at a greater risk of In order to maximize the economic benefits generated by Gilgel-Gibe hydroelectric dam, it is recommended that preventive programmes against malaria and other vector-borne diseases be implemented along the periphery of the reservoir. Health Package programme, including bed net use and health education, early diagnosis and treatment, residual spraying and environmental management be implemented in an integrated way and strengthened to reduce disease burden from vector-borne diseases in communities living in close proximity to the new reservoir.The authors declare that they have no competing interests.DY conceptualized the study design, was involved in the coordination, supervision of data collection, data entry, cleaning, analysis, and drafted the manuscript; WL was involved in the design of the survey and reviewed the manuscript; WVB contributed to the discussion and critically reviewed the manuscript; SG was involved in the supervision of the laboratory work and in drafting the manuscript; HK contributed to the study design, and reviewed the manuscript; LD was involved in the interpretation of the statistical analysis and reviewed the manuscript; NS performed the statistical analysis, interpretation and was involved in drafting and revising the manuscript. All authors read and approved the final manuscript