Parasitemia Density Research Articles

EFFECT OF SCHISTOSOMA HAEMATOBIUM INFECTION ON PLASMODIUM FALCIPARUM MALARIA BURDEN IN LAMBARÉNÉ, GABON

BackgroundMalaria remains the first cause of death in Africa. In endemic area, it overlaps with other infections including helminths infections. It has been shown that there are interactions between the...

EVIDENCE OF PLASMODIUM FALCIPARUM RESISTANCE TO SULPHADOXINE-PYRIMETHAMINE (SP) IN PREGNANT WOMEN ALONG THE SLOPE OF MOUNT CAMEROON

BackgroundMalaria in pregnancy (MiP) has debilitating effects for both mother and neonate, with intermittent preventive treatment in pregnancy (IPTp) central to successful malaria control and management in this vulnerable group....

Comparative prevalence of Plasmodium falciparum malaria in patients attending Okelele Health Centre, Okelele, Ilorin, Nigeria

Background: In Okelele, Ilorin, Kwara State, Nigeria, malaria remains an important public health concern with a little information about its prevalence. Objective: To determine the prevalence of malaria infection at Okelele Health Centre, Okelele, Ilorin. Methodology: A cross-sectional descriptive study in which patients were diagnosed clinically with severe or uncomplicated malaria at the study site was conducted. Rapid diagnostic testing (RDT) for malaria and microscopy using Giemsa staining by thick and thin blood smears were done for study patients. Results: In this study, 200 malaria patients attending Okelele Health Centre, Okelele, Ilorin, were tested for malaria infection, with females having the highest prevalence rates and parasitemia density. The highest positivity rates were found in children <6 years while adolescents had the lowest prevalence rates. Socioeconomic factors of patients such as occupation and education played a major role in malaria prevalence. Conclusion: Although RDT is quick and easy to use, negative malaria cases gotten by RDT should be confirmed by expert microscopy to prevent misdiagnosis of malaria.

Prevalence of malaria parasitaemia among febrile Nigerian children with severe malnutrition in Northwestern Nigeria

Background: Malnutrition and malaria are common in sub-Saharan Africa, and understanding the relationship between protein-energy malnutrition (PEM) and malaria is of great public health importance. Findings from studies evaluating associations between various forms of malnutrition and malaria have been contradictory. This study aimed to determine the prevalence of malaria parasitemia among malnourished children and its various determinants studied. Materials and Methods: This was a cross-sectional study. Ninety febrile children with severe PEM aged 6–59 months (44 males and 46 females) based on modified Wellcome classification were enrolled as subjects and; 90 febrile well-nourished children age and sex matched children as controls. Both subjects and controls were enrolled consecutively in the emergency pediatrics unit of Aminu Kano Teaching Hospital from May to October 2013. The diagnosis of malaria parasitemia was based on the identification of asexual parasites on microscopy after Giemsa staining. Results: The prevalence of malaria parasitemia was 72.2% in the subjects, this was significantly higher than 37.8% in the controls (OR = 4.28, CI = 2.29–8.02). Parasite density was 2122 μL (400–1821). Age, sex, and type of PEM had no significant effect on the prevalence of malaria parasitemia and parasite density (P > 0.05). Plasmodium falciparum (P. falciparum) was seen in all the positive slides. Conclusion and Recommendation: Malnourished children experience more malaria than well-nourished children. Based on the findings of this study malnourished children should have access to the use of insecticide treated nets (ITN) and commence on malaria chemoprophylaxis.

Hematological Parameters and Hemozoin-Containing Leukocytes and Their Association with Disease Severity among Malaria Infected Children: A Cross-Sectional Study at Pawe General Hospital, Northwest Ethiopia

Hematological parameter changes are the most common complications in malaria. We aimed to determine the hematological parameters and hemozoin-containing leukocytes and their association with disease severity in malaria infected children aged between 1 and 15 years. A facility-based cross-sectional study was conducted at Pawe General Hospital from July 31 to December 30, 2014. Demographic and clinical data were collected using structured questionnaire. Blood specimen was collected from each study participant for hematological investigations. Data were analyzed using SPSS version 20. The overall prevalence of anemia was 40.3%, most of which were mildly anemic. Leukocytosis was found in 15.4% of study participants. More than a fourth (27%) of the children had severe malaria. Hemozoin-containing monocytes and neutrophils were found in 80.1% and 58.9% of the study participants, respectively. Under-five years of age (AOR = 3.01, 95% CI: 1.83–7.39, P < 0.001), leukocytosis (AOR = 3.20, 95% CI: 1.65–6.24, P = 0.001), mean hemozoin-containing monocytes >5% (AOR = 6.26, 95% CI: 2.14–14.29, P < 0.001), mean hemozoin-containing neutrophils >5% (AOR = 7.93, 95% CI: 3.09–16.86, P < 0.001), and high density parasitemia (AOR = 1.90, 95% CI: 1.13–3.18, P = 0.015) were associated with severe malaria. Hemozoin-containing leukocytes, leukocytosis, and other identified associated factors should be considered for proper management of children with severe malaria.

Hubungan Polimorfisme Gen FcγRIIA dengan Densitas P. falciparum dan Efikasi Dihidroartemisinin-Piperakuin

FcγRlla dimorphism has been related to the ability of the host to eliminate malaria parasite so it is necessary to investigate the allele polymorphism FcγRlla of population in malaria-endemic areas in Indonesia in order to know the role of immunity in eliminating malaria parasite. A total of 120 samples of Dried Blood Spot (DBS) falciparum malaria acquired from DHP drug efficacy studies in 5 regions in Indonesia were analyzed by Polymerase Chain Reaction (PCR) and sequencing, to look at variants of FcγRIIa-131 allele and its Association with Parasite DensityandEfficacy ofDihydroartemisinin- Piperaquine. The FcγRIIa gene analysis indicated that genotype RH has the highest frequency (50.8%) compared to RR (17.5%) and HH (31.7%). Allele R131 showed a protective effect against High Density Parasitemia (HDP) (>5000 parasites/μL; odds ratio [OR]= 0.133, 95% confidence interval [CI]= 0.053–0.334, P 72 hours; Relative Risk [RR]= 1,571, 95% confidence interval [CI]= 1,005–2,456, P= 0.090). Normal 0 false false false IN X-NONE X-NONE

Prevalence and Pattern of Malaria Parasitaemia among Under-Five Febrile Children Attending Paediatric Out-Patient Clinic at University of Maiduguri Teaching Hospital, Maiduguri

Background: Malaria has remained a major public health problem in Nigeria with the under-five aged children and pregnant women being the most affected. The local epidemiological profile of the disease is dynamic owing to the continuous variation in the various determinants and hence the need for periodic re-evaluation. We aim to determine the prevalence of malaria parasitaemia among the under -five aged children and the effect of various determinants. Material and Method: In this cross-sectional study, 433 outpatients aged below 5 years with fever or history of fever in the previous 72 hours were enrolled. Relevant information was obtained and recorded using a questionnaire. Thick and thin films were prepared from a finger or heel prick for each of the patients and subjected to microscopy. Result: The prevalence of malaria parasitaemia was 27.7%. Age, sex, nutritional status, socioeconomic class, temperature at presentation as well as ownership of insecticide treated nets had no significant effect on the prevalence of malaria (p>0.05). Only P. falciparum was seen in all the positive slides. The parasite density was generally low with 48.3% having parasite densities below 100/μl and only 7.5% had parasite density of ≥1000/μl. Parasite density increased significantly with increasing age (p=0041). Nutritional status as well as other studied factors had no significant effect on parasite density (p>0.05). Conclusion and Recommendation : Prevalence of malaria infection was high in the population studied. It is characterized by low density parasitaemia and hence the need to interpret negative results with caution. Age, gender, socio-economic and nutritional status, temperature at presentation as well as ownership of ITN had no significant effect on prevalence of malaria parasitaemia. There is need to strengthen and scale up various malaria control programs while ensuring proper implementations of programs and activities through effective monitoring and evaluation. Keywords: Prevalence, Pattern, Malaria, Parasitaemia, Under-five Febrile Children, Outpatient Clinic

Therapeutic efficacy of artemether-lumefantrine for treatment of uncomplicated &lt;i&gt;plasmodium falciparum&lt;/i&gt; malaria in Enugu, Nigeria

Purpose: To review current therapeutic efficacy of artemether-lumefantrine (AL) for the treatment of uncomplicated Plasmodium falciparum malaria in patients in Enugu State, Nigeria.Methods: One hundred and fifty four malaria patients from three different Local Government Areas (LGA) of Enugu State, southeastern Nigeria, that fulfilled the inclusion criteria were recruited through rapid diagnostic testing and blood film microscopy. The patients received a 3-day complete dose of AL treatment; they were monitored and 3 mL of blood in EDTA bottle was sampled on days 0, 3, 7, 14 and 28. The samples were evaluated by real-time polymerase chain reaction (RT-PCR) for identification and quantification of Plasmodium falciparum. Clinical and parasitological responses were recorded and analyzed statistically.Results: There was significant decrease (p &gt; 0.002) in patient’s temperature (from 40 to 37 ºC) from day 0 to day 28. There was significant decrease (p &lt; 0.001) between parasite mean density on day 0 and the values on days 3,7,14 and 28, with high prevalence of delayed parasite clearance. There was no early treatment failure, while 4 (3.4 %), 30 (25.4 %), and 84 (75.1 %) had late clinical failure, late parasitological response and adequate clinical and parasitological response, respectively.Conclusion: Artemether – lumefantrine combination therapy reduced fever in malaria patients but failed to totally clear parasitemia density, indicating its reduced therapeutic efficacy in Enugu State, Nigeria.

Effect of Repeated Anthelminthic Treatment on Malaria in School Children in Kenya: A Randomized, Open-Label, Equivalence Trial.

Background. School children living in the tropics are often concurrently infected with plasmodium and helminth parasites. It has been hypothesized that immune responses evoked by helminths may modify malaria-specific immune responses and increase the risk of malaria.Methods. We performed a randomized, open-label, equivalence trial among 2436 school children in western Kenya. Eligible children were randomized to receive either 4 repeated doses or a single dose of albendazole and were followed up during 13 months to assess the incidence of clinical malaria. Secondary outcomes were Plasmodium prevalence and density, assessed by repeat cross-sectional surveys over 15 months. Analysis was conducted on an intention-to-treat basis with a prespecified equivalence range of 20%.Results. During 13 months of follow-up, the incidence rate of malaria was 0.27 episodes/person-year in the repeated treatment group and 0.26 episodes/person-year in the annual treatment group (incidence difference, 0.01; 95% confidence interval, −.03 to .06). The prevalence and density of malaria parasitemia did not differ by treatment group at any of the cross-sectional surveys.Conclusions. Our findings suggest that repeated deworming does not alter risks of clinical malaria or malaria parasitemia among school children and that school-based deworming in Africa may have no adverse consequences for malaria.Clinical Trials Registration. NCT01658774.

Effect of a Malaria Control Program on the Prevalence of Malaria, Fever and Anaemia in Children under Five Years in the Hohoe Municipality of Ghana: A Comparative Analysis of Cross-Sectional Surveys

Background: Malaria and anaemia continue to adversely impact the health of children in Ghana. Hohoe is an area of intense and prolonged, seasonal malaria transmission. In 2006, malaria control programme activities which provided In-secticide Treated Bed-Nets (ITNs) to resident children under five years and Artemisinin Combination Therapies (ACTs) for the management of malaria were introduced into the Hohoe Municipality. Before the introduction of the control programme, baseline surveys were carried out in communities in the Hohoe municipality to determine the prevalence of malaria, fever, anaemia, malaria parasite density, gametocytaemia and ITN ownership and use in June and November 2006 ahead of the intervention programme. Similar surveys were conducted in 2010 after the intervention to assess changes in the earlier indicators in the same communities. This report presents an evaluation of the intervention by comparing findings before and after the malaria control interventions. Methods: In 2010, two community-based surveys were carried out in thirty communities among children aged five years and below. The first one was at the beginning of the rainy and high malaria transmission season in June and the other was in November at the end of the rainy season. The surveys were to determine the prevalence of malaria, fever, anaemia and ITN ownership, use and effectiveness among children less than 5 years. Data were collected in the form of interviews using questionnaire and collection of biological samples. Findings were compared to those similar surveys conducted in the same communities and age groups in 2006. Pr-testi was used to analyze two sample tests for proportions and t-test was used for means. Findings: Malaria prevalence decreased by 20% [9.0% vs. 7.2%; p = 0.0.40], fever decreased by 47.8% [2.3% vs. 1.2%; p = 0.008] and anaemia decreased by 32.9% [7.8% vs. 5.3%; p = 0.002]. ITN ownership increased by 67.9% [20.8% vs. 64.8%; p < 0.001], ITN use increased by 64.2% [15.1% vs. 42.2%; p < 0.001] and ITN effectiveness increased by 41.7% [20.0% vs. 34.3%; p < 0.001]. The proportion of children with high density parasitaemia reduced by 17.9% [2.8% vs. 2.3%; p = 0.223]. Gameto-cytaemia decreased by 82.5% [0.8% vs. 0.14%; p = 0.002. Similarly data comparing 2006 and 2010 post-rainy season showed that malaria prevalence decreased by 16.8% [40.4% vs. 33.6%; p < 0.001], fever decreased by 14% [5.0% vs. 4.3%; p = 0.347] and anaemia decreased by 64.2% [12% vs. 4.3%; p < 0.001]. The proportion of children with high density parasitaemia also reduced by 69.5% [10.5% vs. 3.2%; p < 0.001] and gametocytaemia decreased by 78.5% [0.8% vs. 0.17%; p = 0.008]. Conclusion: This study suggested that there was an association between the current intervention and reduction in the prevalence of malaria, fever and anaemia. High parasite density and gametocytaemia prevalence have also significantly reduced over the five years of the introduction of the control measures. There has also been a significant increase in the ownership and use of ITNs.

Experimental Plasmodium vivax infection of key Anopheles species from the Brazilian Amazon

BackgroundAnopheles darlingi is the major malaria vector in countries located in the Amazon region. Anopheles aquasalis and Anopheles albitarsis s.l. are also proven vectors in this region. Anopheles nuneztovari s.l. and Anopheles triannulatus s.l. were found infected with Plasmodium vivax; however, their status as vectors is not yet well defined. Knowledge of susceptibility of Amazon anopheline populations to Plasmodium infection is necessary to better understand their vector capacity. Laboratory colonization of An. darlingi, the main Amazon vector, has proven to be difficult and presently An. aquasalis is the only available autonomous colony.MethodsLarvae of An. darlingi, An. albitarsis s.l., An. nuneztovari s.l. and An. triannulatus s.l. were collected in the field and reared until adult stage. Adults of An. aquasalis were obtained from a well-established colony. Mosquitoes were blood-fed using a membrane-feeding device containing infected blood from malarial patients.The infection of the distinct Anopheles species was evaluated by the impact variance of the following parameters: (a) parasitaemia density; (b) blood serum inactivation of the infective bloodmeal; (c) influence of gametocyte number on infection rates and number of oocysts. The goal of this work was to compare the susceptibility to P. vivax of four field-collected Anopheles species with colonized An. aquasalis.ResultsAll Anopheles species tested were susceptible to P. vivax infection, nevertheless the proportion of infected mosquitoes and the infection intensity measured by oocyst number varied significantly among species. Inactivation of the blood serum prior to mosquito feeding increased infection rates in An. darlingi and An. triannulatus s.l., but was diminished in An. albitarsis s.l. and An. aquasalis. There was a positive correlation between gametocyte density and the infection rate in all tests (Z = −8.37; p < 0.001) but varied among the mosquito species. Anopheles albitarsis s.l., An. aquasalis and An. nuneztovari s.l. had higher infection rates than An. darlingi.ConclusionAll field-collected Anopheles species, as well as colonized An. aquasalis are susceptible to experimental P. vivax infections by membrane feeding assays. Anopheles darlingi, An. albitarsis s.l. and An. aquasalis are very susceptible to P. vivax infection. However, colonized An. aquasalis mosquitoes showed the higher infection intensity represented by infection rate and oocyst numbers. This study is the first to characterize experimental development of Plasmodium infections in Amazon Anopheles vectors and also to endorse that P. vivax infection of colonized An. aquasalis is a feasible laboratory model.

Establishment Efficiency Among Clones of the Malaria Parasite,Plasmodium mexicanum, for Mixed-Clone Infections in Its Natural Lizard Host

Within genetically diverse infections of malaria parasites ( Plasmodium spp.), the relative proportions of genetic clones in the vertebrate host's blood can influence clonal competition, transmission success, gametocyte sex ratio, and virulence. Clonal proportions depend on establishment success of each clone when they enter a new host and on subsequent differences in rates of asexual replication and clearance. Both of these life history traits could be influenced by clone genotype. To assess genetic (clonal) influences on both establishment success and later changes in relative proportion for the lizard malaria parasite Plasmodium mexicanum , 7 naturally infected fence lizards harboring a single clone of P. mexicanum served as donors to initiate replicate experimental infections containing each of the clones and combinations of 2 clones. Measured were relative establishment success of each clone, change in relative proportions over time, and rate of increase of parasite density and total parasitemia. Relative clonal proportions were determined using microsatellite markers. Rates of increase in the parasitemia and degree of change in relative proportions were not correlated, so both rapidly and slowly growing infections could show either little or substantial change in clonal proportions over time. There was a significant clone effect on establishment efficiency but not on later changes in relative proportions. These results argue for a combination of genetic and environmental (host) effects on the success of P. mexicanum clones in genetically complex infections. The maintenance of genetic variation for establishment success, but not subsequent replication rate or shifts in relative proportion, suggests trade-offs between these traits during life history evolution of malaria parasites.

Definition of hyperparasitemia in severe falciparum malaria should be updated

Dear editor, Hyperparasitemia is one criterion of severe falciparum malaria by World Health Organization (WHO) for more than two decades[1]. Although there is a correlation between density of parasittemia and severity of malaria, some individuals with high parasite counts may not be severely ill, whereas others with low parasitemia may have ultimately fatal infections. Hyperparasitemia (more than 5% infected erythrocytes or more than 250 000 parasites/µL) indicated poor prognosis in cerebral malaria in Thai adults[2]. In areas where malaria is of low edemicity, patients with Plasmodium falciparum parasitemia above 100 000/µL (above 250 parasites per thick blood film or 2% infected erythrocytes) warrant careful observation, especially when hematocrit is low[3]. The overall mortality of uncomplicated falciparum malaria was 0.1%, but in patients with parasitemia of >4% it was 3%, however, in areas of moderate or high transmission, much higher parasitemia is often well tolerated[4]; thus, in 2006, WHO had not enough evidence to provide a firm recommendation on the definition of hyperparasitema, although >5% parasitemia in a low-transmission setting and >10% in a higher transmission setting are commonly used. In 2010, WHO defined hyperparasitemia as >2%/100 000/µL in low intensity transmission areas or >5% or 250 000/µL in areas of high stable malaria transmission intensity[5]. In 2012, the latest study in Thailand (where is low-transmission area) showed that falciparum parasitemia density of 0.5% was considered a cutoff point for discrimination between severity levels of falciparum malaria patients[6]. Therefore, in the past two decades, definition of hyperparasitemia contributing to severe malaria showed a lower trend of cutoff points, possibly patients came to seek treatment more early than two decades and possibly widespread use of potent antimalarial drugs today (e.g., artemisinin combination therapy or ACT) which were better than the old drug quinine. Artemisin derivatives clear parasites more rapidly than quinine. They also kill ring to mature stages of parasites whereas quinine has effect on only mature parasite stages. ACT may cause less parasite clearance time after treatment than quinine. However, this may cause less asymptomatic parasitemia and less or absence partial malaria immunity in population in malaria endemic areas. When patients have malaria infection, even low density of parasite count, the patients may have severe malaria and the low parasite density of these patients is enough to be considered as hyperparasitemia for them. Use of buffy coat thick films in detecting malaria parasites in severe patients with negative conventional thick films may help diagnosis of malaria[7]. In conclusion, trend of hyperparasitemia of falciparum malaria has declined continuously. National health authorities in each countries where malaria is endemic should be regularly monitored the percentage of parasitemia or the number or parasite count causing severe malaria of the patients in the countries. Therefore, definition of hyperparasitemia may not be similar in different areas and in different time in the future.

Interleukin (IL)-13 promoter polymorphisms (-7402 T/G and -4729G/A) condition susceptibility to pediatric severe malarial anemia but not circulating IL-13 levels

In holoendemic Plasmodium falciparum transmission areas such as western Kenya, severe malarial anemia [SMA, hemoglobin (Hb) < 6.0 g/dL, with any density parasitemia] is the most common clinical manifestation of severe malaria resulting in high rates of pediatric morbidity and mortality in these regions. Previous studies associated interleukin (IL)-13 with pathogenesis of different infectious diseases, including P. falciparum malaria. However, the functional roles of polymorphic variants within the IL-13 promoter in conditioning susceptibility to SMA remain largely unexplored. As such, the association between the IL-13 variants -7402 T/G (rs7719175) and -4729G/A (rs3091307) and susceptibility to SMA was determined in children (n = 387) presenting with clinical symptoms of falciparum malaria and resident in a holoendemic transmission region in western Kenya. Our results indicated no difference in the proportions of individual genotypes among children presenting with non-SMA (n = 222) versus SMA (n = 165). Similarly, there was no associations between the individual genotypes (-7402 T/G and -4729G/A) and SMA. Additional analyses, however, revealed that proportions of individuals with -7402 T/-4729A (TA) haplotype was significantly higher in children presenting with SMA than non-SMA group (P = 0.043). A further multivariate logistic regression analyses, controlling for confounding factors, demonstrated that carriage of the TA haplotype was associated with increased susceptibility to SMA (OR; 1.564, 95% CI; 1.023-2.389, P = 0.039). In addition, circulating levels of IL-13 were comparable between the clinical groups as well as across genotypes and haplotypes. Collectively, findings presented here suggest that haplotypes within the IL-13 promoter at -7402 T/G and -4729G/A may modulate SMA pathogenesis, but do not affect circulating IL-13 levels.

Four-Year Efficacy of RTS,S/AS01E and Its Interaction with Malaria Exposure

BackgroundThe candidate malaria vaccine RTS,S/AS01E has entered phase 3 trials, but data on long-term outcomes are limited.MethodsFor 4 years, we followed children who had been randomly assigned, at 5 to 17 months of age, to receive three doses of RTS,S/AS01E vaccine (223 children) or rabies vaccine (224 controls). The end point was clinical malaria (temperature of ≥37.5°C and Plasmodium falciparum parasitemia density of >2500 parasites per cubic millimeter). Each child's exposure to malaria was estimated with the use of the distance-weighted local prevalence of malaria.ResultsOver a period of 4 years, 118 of 223 children who received the RTS,S/AS01E vaccine and 138 of 224 of the controls had at least 1 episode of clinical malaria. Vaccine efficacies in the intention-to-treat and per-protocol analyses were 29.9% (95% confidence interval [CI], 10.3 to 45.3; P=0.005) and 32.1% (95% CI, 11.6 to 47.8; P=0.004), respectively, calculated by Cox regression. Multiple episodes were common, with 551 and 618 malarial episodes in the RTS,S/AS01E and control groups, respectively; vaccine efficacies in the intention-to-treat and per-protocol analyses were 16.8% (95% CI, −8.6 to 36.3; P=0.18) and 24.3% (95% CI, 1.9 to 41.6; P=0.04), respectively, calculated by the Andersen–Gill extension of the Cox model. For every 100 vaccinated children, 65 cases of clinical malaria were averted. Vaccine efficacy declined over time (P=0.004) and with increasing exposure to malaria (P=0.001) in the per-protocol analysis. Vaccine efficacy was 43.6% (95% CI, 15.5 to 62.3) in the first year but was −0.4% (95% CI, −32.1 to 45.3) in the fourth year. Among children with a malaria-exposure index that was average or lower than average, the vaccine efficacy was 45.1% (95% CI, 11.3 to 66.0), but among children with a malaria-exposure index that was higher than average it was 15.9% (95% CI, −11.0 to 36.4).ConclusionsThe efficacy of RTS,S/AS01E vaccine over the 4-year period was 16.8%. Efficacy declined over time and with increasing malaria exposure. (Funded by the PATH Malaria Vaccine Initiative and Wellcome Trust; ClinicalTrials.gov number, NCT00872963.)

A longitudinal study on anaemia in children with Plasmodium falciparum infection in the Mount Cameroon region: prevalence, risk factors and perceptions by caregivers.

BackgroundIn heavily endemic malaria areas, it is almost inevitable that malarial infection will be associated with anaemia, although malaria may not be the prime cause of it. Anaemia is a major public health problem in Cameroon. We hypothesized that, factors other than falciparum malaria account for anaemia in the study area.MethodsA longitudinal study was conducted among 351 Plasmodium falciparum positive children to determine the prevalence, risk factors and the perception of anaemia by the caregivers in a semi-rural community. The investigative methods included the use of a structured questionnaire, clinical evaluation and laboratory investigations.ResultsAt enrolment the overall prevalence of anaemia as assessed by Hb concentration (Hb < 11 g/dl) was 80.3% (282). Following treatment the prevalence of persistent anaemia was 6% and 46.2% of the children achieved haematological recovery by day 42. Exploratory multiple linear regression analysis showed the following; parasitaemia density (P < 0.01), enlarged spleen (P < 0.05), duration of fever > 2 days (P < 0.01), high white blood cell count (P < 0.001), sex (P < 0.05), iron status indicators (ferritin and transferrin) (P < 0.001), level of education of the caregiver (P < 0.05), management of onset of malaria by caregiver (P < 0.005) and wasting (P < 0.05) to be risk factors for anaemia in children with falciparum infection. Approximately 75.5% (265) of the caregivers had some knowledge about anaemia.ConclusionThe identified risk factors revealed the important contributors to the pathogenesis of anaemia in the Mount Cameroon region. Control efforts should therefore be directed towards proper health education emphasizing on proper health seeking behaviour and attitudes of the population.

The Plasmodium falciparum Erythrocyte Invasion Ligand Pfrh4 as a Target of Functional and Protective Human Antibodies against Malaria

BackgroundAcquired antibodies are important in human immunity to malaria, but key targets remain largely unknown. Plasmodium falciparum reticulocyte-binding-homologue-4 (PfRh4) is important for invasion of human erythrocytes and may therefore be a target of protective immunity.MethodsIgG and IgG subclass-specific responses against different regions of PfRh4 were determined in a longitudinal cohort of 206 children in Papua New Guinea (PNG). Human PfRh4 antibodies were tested for functional invasion-inhibitory activity, and expression of PfRh4 by P. falciparum isolates and sequence polymorphisms were determined.ResultsAntibodies to PfRh4 were acquired by children exposed to P. falciparum malaria, were predominantly comprised of IgG1 and IgG3 subclasses, and were associated with increasing age and active parasitemia. High levels of antibodies, particularly IgG3, were strongly predictive of protection against clinical malaria and high-density parasitemia. Human affinity-purified antibodies to the binding region of PfRh4 effectively inhibited erythrocyte invasion by P. falciparum merozoites and antibody levels in protected children were at functionally-active concentrations. Although expression of PfRh4 can vary, PfRh4 protein was expressed by most isolates derived from the cohort and showed limited sequence polymorphism.ConclusionsEvidence suggests that PfRh4 is a target of antibodies that contribute to protective immunity to malaria by inhibiting erythrocyte invasion and preventing high density parasitemia. These findings advance our understanding of the targets and mechanisms of human immunity and evaluating the potential of PfRh4 as a component of candidate malaria vaccines.

The Effects of Malaria and Intermittent Preventive Treatment During Pregnancy on Fetal Anemia in Malawi

Fetal anemia is common in malarious areas and is a risk factor for infant morbidity and mortality. Malaria during pregnancy may cause decreased cord hemoglobin (Hb) and fetal anemia among newborns. Intermittent preventive treatment during pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) is protective against malaria but may also affect hematopoiesis and contribute to fetal anemia. Peripheral, placental, and cord blood were examined for malaria parasitemia and Hb concentration in a cross-section of 3848 mothers and infants delivered at Queen Elizabeth Central Hospital in Blantyre, Malawi between 1997 and 2006. Unconditional linear and logistic regressions were performed with multiple imputation for missing covariates to assess the associations between malaria, IPTp with SP, and fetal anemia. The overall prevalence of fetal anemia was 7.9% (n = 304). Malaria parasitemia at delivery was associated with an adjusted decrease in cord Hb of -0.24 g/dL (95% confidence interval [CI], -.42 to -.05). The adjusted prevalence odds ratio for the effect of malaria on fetal anemia was 1.41 (95% CI, 1.05-1.90). Primigravidae who did not take IPTp had infants at highest risk for fetal anemia, and density of parasitemia was correlated with the decrease in cord Hb. There was no significant association between SP use and cord Hb or fetal anemia. Malaria during pregnancy, but not IPTp, decreases cord Hb and is a risk factor for fetal anemia in Malawi. Intermittent preventive treatment during pregnancy with SP may continue to be safe and effective in preventing malaria during pregnancy and fetal anemia despite development of SP resistance.

Severe and uncomplicated falciparum malaria in children from three regions and three ethnic groups in Cameroon: prospective study

BackgroundTo identify the factors that account for differences in clinical outcomes of malaria as well as its relationship with ethnicity, transmission intensity and parasite density.MethodsA prospective study was conducted in nine health facilities in the Centre, Littoral and South West regions of Cameroon, and in three ethnic groups; the Bantu, Semi-Bantu and Foulbe. Children aged one month to 13 years, with diagnosis suggestive of malaria, were recruited and characterized using the WHO definition for severe and uncomplicated malaria. Malaria parasitaemia was determined by light microscopy, haematological analysis using an automated haematology analyser and glucose level by colorimetric technique.ResultsOf the febrile children screened, 971 of the febrile children screened fulfilled the inclusion criteria for specific malaria clinical phenotypes. Forty-nine (9.2%) children had cerebral malaria, a feature that was similar across age groups, ethnicity and gender but lower (P < 0.004) in proportion in the Centre (3.1%, 5/163) compared to the Littoral (11.3%, 32/284) and South West (13.6%, 12/88) regions. Severe anaemia was the most frequent severe disease manifestation, 28.0% (248/885), which was similar in proportion across the three ethnic groups but was more prevalent in females, less than 60 months old, and the Centre region. About 20% (53/267) of the participants presented with respiratory distress, a clinical phenotype independent of age, gender and ethnicity, but highest (P < 0.001) in the Centre (55%, 11/20) compared to the Littoral (27.3%, 3/11) and South West (16.5%, 39/236) regions. Uncomplicated malaria constituted 27.7% (255/920) of hospital admissions and was similar in proportion with gender and across the three ethnic groups but more prevalent in older children (≥ 60 months) as well as in the South West region. The density of malaria parasitaemia was generally similar across clinical groups, gender and ethnicity. However, younger children and residents of the Centre region carried significantly higher parasite loads, with the burden heavier in the Semi-Bantu compared to their Bantu (P = 0.009) and Foulbe (P = 0.026) counterparts in the Centre region. The overall study case fatality was 4.8 (47/755), with cerebral malaria being the only significant risk factor associated with death. Severe anaemia, though a common and major clinical presentation, was not significantly associated with risk of death.ConclusionAbout half of the acutely febrile children presented with severe malaria, the majority being cases of severe malaria anaemia, followed by respiratory distress and cerebral malaria. The latter two were less prevalent in the Centre region compared to the other regions. Cerebral malaria and hyperpyrexia were the only significant risk factors associated with death.

Association between Sickle Cell Trait and Low Density Parasitaemia in a P. falciparum Malaria Holoendemic Region of Western Kenya

Aims: The frequency of the mutant gene for sickle cell is widely distributed in the subSaharan Africa, the Middle East, and the Indian subcontinent. There is epidemiologic evidence that sickle cell trait confers a survival advantage against malaria and that the selection pressure due to malaria has resulted in high frequencies of the mutant gene in areas of high malaria transmission. We carried out a study to look at the relationship between sickle cell trait, age, haemoglobin level, and malaria parasite density. Methods: We carried out a cross-sectional study between the months of October and December, 2004 in Kombewa Division of Kisumu West District, a P. falciparum malaria