The influence of zinc supplementation on morbidity due to Plasmodium falciparum: a randomized trial in preschool children in Papua New Guinea

Zinc is crucial for normal immune function and can reduce morbidity from multiple infectious diseases. To determine the influence of zinc on malaria morbidity we conducted a randomized placebo-controlled trial of daily zinc supplementation in children residing in a malaria endemic region of Papua New Guinea. A total of 274 preschool children aged 6 to 60 months were given 10 mg elemental zinc (n = 136) or placebo (n = 138) for 6 days a week for 46 weeks. Slide-confirmed malaria episodes were detected by surveillance of cases self-reporting to a local health center. Cross-sectional surveys were conducted at the beginning, middle, and end of the study to assess infection rates, parasite density, spleen enlargement, and hemoglobin levels. Zinc supplementation resulted in a 38% (95% CI 3-60, P = 0.037) reduction in Plasmodium falciparum health center-based episodes, defined as parasitemia > or = 9200 parasites/microl with axial temperature > or = 37.5 degreesC or reported fever. Episodes accompanied by any parasitemia were also reduced by 38% (95% CI 5-60, P = 0.028), and episodes with parasitemia > or = 100,000/microl were reduced by 69% (95% CI 25-87, P = 0.009). There was no evidence of the effects of zinc on Plasmodium vivax morbidity or on health center attendance for causes other than P. falciparum. Zinc had no consistent effect on cross-sectional malariometric indices. Although P. falciparum prevalence tended to be lower at the end of the study in children given the placebo, such changes were absent at the mid-study survey. These results suggest that improved dietary zinc intake may reduce morbidity due to P. falciparum.     

Insecticide-treated bednets for the prevention of Plasmodium falciparum malaria in Cambodia: a cluster-randomized trial

OBJECTIVES: To validate and quantify the impact of insecticide-treated bednets (ITN) on malaria morbidity and mortality in Cambodia. METHODS: A paired, cluster-randomized trial of ITN was conducted in Rattanakiri, North East Cambodia. Thirty-four villages with a total population of 10,726 were randomized to receive deltamethrin-impregnated bednets or to control (no net provision). Cross-sectional surveys measured Plasmodium falciparum prevalence at baseline and 10 months after ITN distribution. Village malaria volunteers in control and intervention villages treated dipstick-positive P. falciparum cases with artesunate and mefloquine. The resulting passive surveillance data were used as an estimate of the incidence of clinical P. falciparum infections. RESULTS: There was a protective efficacy of 28% in P. falciparum incidence (adjusted rate ratio 0.72, 95% CI 0.47-1.08) and 9% in P. falciparum prevalence (adjusted prevalence ratio 0.91, 95% CI 0.65-1.28) in ITN relative to control villages; however, neither of these estimates reached statistical significance. Individual-level analysis indicated a greater reduction in P. falciparum prevalence among under 5-year-olds (adjusted OR = 0.63, 95% CI 0.26-1.53) compared to older individuals (interaction P = 0.042). The protective efficacy of 35% (95% CI -28, 67%) with respect to clinical P. falciparum incidence in under 5-year-olds was more pronounced than the corresponding estimates for prevalence but was again not significant. CONCLUSIONS: Lack of statistical significance in the results is likely to be due to a lack of power. The analysis provides further evidence for ITN effectiveness in South East Asia, particularly among individuals under 5 years of age.     

Reduced prevalence of Plasmodium falciparum infection and of concomitant anaemia in pregnant women with heterozygous G6PD deficiency

Glucose-6-phosphate dehydrogenase (G6PD) deficiency confers protection against malaria in children, yet its role in malaria in pregnancy is unknown. In a cross-sectional study among 529 pregnant Ghanaian women, Plasmodium falciparum infection, anaemia and G6PD genotypes were assessed. Of these, 30.4% were heterozygous and 2.6% were homozygous for G6PD deficiency. The prevalence of P. falciparum infection decreased from 66% in G6PD-normal women to 58% in heterozygotes, and to 50% in individuals with homozygous G6PD deficiency (Chi2(trend) = 4.4, P = 0.04). Multivariate analysis revealed that in multigravid women but not in primigravidae, heterozygous G6PD deficiency was associated with a reduced risk of P. falciparum infection (Odds ratio (OR), 0.6; 95% confidence interval (95% CI), [0.4-0.9]). This protection against infection was limited to the third trimenon of pregnancy. In addition, heterozygous G6PD deficiency was associated with a reduced risk of anaemia among infected multigravidae (OR, 0.5 [0.3-1.0]). Pregnancy is a period of high vulnerability to malaria. The results of this study provide evidence for protection against malaria in pregnancy caused by heterozygous G6PD deficiency. This advantage, even if confined to multigravid women, may contribute to the selection of G6PD variants in malaria-endemic regions.     

Malaria prevalence and associated risk factors in Eritrea

A parasitological cross-sectional survey was undertaken from September 2000 through February 2001 to estimate the prevalence of malaria parasitemia in Eritrea. A total of 12,937 individuals from 176 villages were screened for both Plasmodium falciparum and Plasmodium vivax parasite species using the OptiMal Rapid Diagnostic Test. Malaria prevalence was generally low but highly focal and variable with the proportion of parasitemia at 2.2% (range: 0.4% to 6.5%). Despite no significant differences in age or sex-specific prevalence rates, 7% of households accounted for the positive cases and 90% of these were P. falciparum. Multivariate regression analyses revealed that mud walls were positively associated with malaria infection (OR [odds ratio] = 1.6 [95% CI: 1.2, 2.2], P < 0.008). For countries with low and seasonal malaria transmission, such information can help programs design improved strategic interventions.     

Prevention of malaria in Afghanistan through social marketing of insecticide-treated nets: evaluation of coverage and effectiveness by cross-sectional surveys and passive surveillance

Malaria is often a major health problem in countries undergoing war or conflict owing to breakdown of health systems, displacement of vulnerable populations, and the increased risk of epidemics. After 23 years of conflict, malaria has become prevalent in many rural areas of Afghanistan. From 1993 to the present, a network of non-governmental organizations, co-ordinated by HealthNet International, has operated a programme of bednet sales and re-treatment in lowland areas. To examine whether a strategy based on insecticide-treated nets (ITN) is a viable public health solution to malaria, communities were given the opportunity to buy nets and then monitored to determine population coverage and disease control impact. This was carried out using two contrasting methods: cross-sectional surveys and passive surveillance from clinics using a case-control design. Nets were purchased by 59% of families. Cross-sectional surveys demonstrated a 59% reduction in the risk of Plasmodium falciparum infection among ITN users compared with non-users (OR 0.41; 95% CI 0.25-0.66). The passive surveillance method showed a comparable reduction in the risk of symptomatic P. falciparum malaria among ITN users (OR 0.31; 95% CI 0.21-0.47). The cross-sectional method showed a 50% reduction in risk of P. vivax infection in ITN users compared with non-users (OR 0.50; 95% CI 0.17-1.49) but this effect was not statistically significant. The passive surveillance method showed a 25% reduction in the risk of symptomatic P. vivax malaria (OR 0.75; 95% CI 0.66-0.85). ITN appeared to be less effective against P. vivax because of relapsing infections; hence an effect took more than one season to become apparent. Passive surveillance was cheaper to perform and gave results consistent with cross-sectional surveys. Untreated nets provided some protection. Data on socioeconomic status, a potential confounding factor, was not collected. However, at the time of net sales, there was no difference in malaria prevalence between buyers and non-buyers. The abundance of Anopheles stephensi, the main vector, did not appear to be affected by ITN. ITN constitute one of the few feasible options for protection against malaria in chronic emergencies.     

Insecticide-treated curtains reduce the prevalence and intensity of malaria infection in Burkina Faso

A large, randomized controlled trial to investigate the impact of insecticide-treated curtains (ITC) on child mortality was conducted in an area of seasonal, holoendemic malaria in Burkina Faso. 158 communities totalling some 90,000 people were censused and grouped into 16 geographical clusters, 8 of which were randomly selected to receive ITC in June-July 1994, just prior to the rainy season. In September-October 1995, at the peak period of malaria transmission, a cross-sectional survey was conducted in 84 of the villages. A random sample of 905 children aged 6-59 months was identified and visited. 763 children (84%) were present at the time of the visit and recruited into the study. Mothers were asked about fever in the past 24 h, the child's temperature was taken, and a sample of blood collected to identify and quantify malaria infections and to measure haemoglobin (Hb) levels. Children protected by ITC were less likely to be infected with Plasmodium falciparum (risk ratio = 0.92; 95% CI 0.86, 0.98) or P. malariae (risk ratio = 0.42, 95% CI 0.19, 0.95). The mean intensity of P. falciparum infections was lower among children protected by ITC (899 vs. 1583 trophozoites/microliter; P < 0.001), while the mean Hb level was 0.4 g/dl higher (P < 0.001). While we found no evidence that ITC had an impact on the prevalence of malaria-associated fever episodes, the confidence intervals around our estimates of the impact of ITC on malaria morbidity were wide. We conclude that widespread implementation of ITC in this area of high malaria transmission led to a modest reduction in the prevalence of malaria infection and to a more substantial reduction in the intensity of these infections which caused increased Hb levels. We were unable to demonstrate any impact of ITC on malaria morbidity, but the wide confidence intervals around our point estimates do not preclude the possibility of a substantial impact.     

Rapid onset of transmission-reducing antibodies in javanese migrants exposed to malaria in papua, indonesia

Transmission of Plasmodium falciparum malaria is initiated by sexual stages in the mosquito. Anti-Pfs48/45 and anti-Pfs230 sexual stage antibodies that are ingested together with parasites can reduce parasite development and subsequently malaria transmission. Acquisition of sexual stage immunity was studied in a cohort of 102 non-immune Javanese individuals migrating to hyperendemic Papua Indonesia. Seroprevalence of antibodies against Pfs48/45 and Pfs230 and functional transmission-reducing activity (TRA) were measured upon arrival and at 6, 12, and 24 months. Asexual parasitemia and gametocytemia were assessed every two weeks. The TRA and seroreactivity increased with the number of P. falciparum infections. The longitudinally sustained association between TRA and antibodies against Pfs48/45 (odds ratio [OR] = 3.74, 95% confidence interval [CI] = 1.51-9.29) and Pfs230 (OR = 3.72, 95% CI = 1.36-10.17) suggests that functional transmission reducing immunity is acquired after limited exposure to infection.     

Field trial of the RTM dipstick method for the rapid diagnosis of malaria based on the detection of Plasmodium falciparum HRP-2 antigen in whole blood

The performance of the Quorum RapidTest Malaria (RTM) dipstick method that detects Plasmodium falciparum histidine-rich protein-2 (PfHRP-2) antigen in whole blood was evaluated in a malaria endemic area. Results were compared with conventional Giemsa-stained blood films. Of 306 people tested 37.9% (116/306) were found to be parasitaemic; of these 66.4% (77/116) were P. vivax and 32.8% (38/116) were P. falciparum infections. There was only one (0.9%) mixed P. falciparum plus P. vivax infection.The RTM test was positive in 35/36 patients with P. falciparum identified on blood smear examination, resulting in a sensitivity of 97.2% [95% confidence interval (CI): 91.6-102.8%]. Specificity was 96.3% (95% CI: 93.9-98.6%).The RTM test had a positive predictive value of 77.8% (95% CI: 65.7-89.9%) and a negative predictive value of 99.6% (95% CI: 98.4-100.8%). Of the 10 false positives, seven reported recent malaria episode and treatment, indicating persistence of antigenaemia. If these were assumed truly infected, the positive predictive value is increased to 93.3% (95% CI: 85.8-100.8%).The RTM test was positive in all seven P. falciparum infections with gametocytes and one mixed infection, but was negative in all falciparum gametocytes and relapsing fever cases. All but one P. vivax infection gave negative result on the RTM test.The RTM test missed one patient with parasitaemia. The test is highly sensitive and specific requiring no instrument or trained personnel. It appears to be a very useful tool for rapid diagnosis of malaria, especially in the rural health institutions with limited diagnostic facilities.     

Microscopic and sub-microscopic Plasmodium falciparum infection, but not inflammation caused by infection, is associated with low birth weight

Pregnancy-associated malaria is one of the leading causes of low birth weight in malaria endemic areas. In this study, 145 parturient women residing in areas endemic for Plasmodium falciparum in Lambaréné, Gabon, were recruited into the study after delivery, and the association of maternal P. falciparum infection, inflammatory response, and birth weight was studied. At delivery, 10% (15) of the mothers (12 were positive in both peripheral and placental blood smears, 1 was positive in peripheral blood only, and 2 were positive in placenta blood only) were positive for P. falciparum by microscopy and 23% (30) by real-time polymerase chain reaction (PCR). The level of C-reactive protein (CRP) was significantly elevated in microscopically P. falciparum-positive pregnant women (34 mg/L; 95% CI: 3-458) but not in those with sub-microscopic infections (6 mg/L; 95% CI: 1-40) compared with those free of P. falciparum infection (7 mg/L; 95% CI: 1-43). In a multivariate analysis, the presence of microscopic (adjusted OR = 28.6, 95% CI = 4.8-169.0) or sub-microscopic (adjusted OR = 13.2, 95% CI = 2.4-73.0) P. falciparum infection in pregnant women and age of mothers < 21 years (adjusted OR = 9.7 CI = 1.0-89.7), but not CRP levels, were independent predictors for low birth weight. This finding may have important operational implications and emphasizes the need for appropriate diagnostic methods in studies evaluating the outcome of pregnancy-associated malaria.     

Epidemiology of malaria in an area of low transmission in central India

A longitudinal study on malaria was carried out from 2003 to 2005 in an area of unstable malaria in the Panna district in central India. Both Plasmodium vivax and P. falciparum were prevalent; however, the risk of P. falciparum malaria was 31.6% (95% confidence interval [CI] = 29.6-33.6%), which is four times higher compared with that of P. vivax malaria (7.8%, 95% CI = 6.7-9%). An increasing trend was recorded in malaria prevalence from 30.2% in 2003 to 46.6% in 2004 (odds ratio [OR] = 2.0, 95% CI = 1.6-2.5) that increased to 58.6% in 2005 (OR = 1.6, 95% CI = 1.2-2.1). This increase was statistically significant (chi(2) = 120.5, degrees of freedom = 2, P < 0.0001). Anopheles culicifacies was the dominant vector of malaria and showed partial (< 50%) resistance to DDT, which indicated that DDT can still be used. Improved access to treatment facilities, combination therapy, and vector control appears to be the most promising method for controlling malaria in this region.     

Short report: therapeutic efficacy of chloroquine combined with primaquine against Plasmodium falciparum in northeastern Papua,Indonesia

Chloroquine combined with primaquine was evaluated for therapy of uncomplicated malaria caused by Plasmodium falciparum in nonimmune Javanese migrants to northeastern Papua, Indonesia. Subjects were randomized to treatment with standard chloroquine therapy (25 mg/kg in 3 doses over the course of 48 hours) with 30 mg primaquine administered daily for 28 days (n = 25) or a placebo of primaquine (n = 28). The 14-day cumulative incidence of therapeutic failure was 56% with primaquine and 79% with placebo (odds ratio [OR], 0.35; 95% confidence interval [CI], 0.1-1.3; P = 0.08). Primaquine administered daily created a marginally significant improvement in therapeutic efficacy at day 14, but not at day 7 (20% versus 36%; OR, 0.2; 95% CI, 0.1-1.8; P = 0.2) or day 28 (82% versus 93%; OR, 0.31; 95% Cl, 0.04-2.1; P = 0.23). This report corroborates studies suggesting that therapeutic doses of primaquine exert no discernible effect on parasitemia by P. falciparum.     

Age-dependent impairment of IgG responses to glycosylphosphatidylinositol with equal exposure to Plasmodium falciparum among Javanese migrants to Papua,Indonesia

Immune responses directed at glycosylphosphatidylinositol (GPI) anchors of Plasmodium falciparum may offer protection against symptomatic malaria. To independently explore the effect of age on generation of the anti-GPI IgG response, we measured serum anti-GPI IgGs in a longitudinal cohort of migrant Javanese children (6-12 years old) and adults (> or = 20 years old) with equivalent numbers of exposures to P. falciparum in Papua, Indonesia. While the peak response in adults was achieved after a single infection, comparable responses in children required > or = 3-4 infections. Significantly fewer children (16%) than adults (41%) showed a high (optical density > 0.44) anti-GPI IgG response (odds ratio [OR] = 3.8, 95% confidence interval [CI] = 2.3-6.3, P < 0.0001), and adults were more likely to show a persistently high response (OR = 5.5, 95% CI = 1.0-56.8, P = 0.03). However, the minority of children showing a strong response were significantly less likely to experience symptoms with subsequent parasitemia compared with those with a weak response (OR = 4.0, 95% CI = 1.1-13.8, P = 0.02). This effect was not seen among high- and low-responding adults (OR = 1.2, 95% CI = 0.5-2.8, P = 0.60). Host age, independent of cumulative exposure, apparently represents a key determinant of the quantitative and qualitative nature of the IgG response to P. falciparum GPI.     

Association of ABO blood group and P. falciparum malaria related outcomes: a cross-sectional study in Ethiopia

Studies elucidate conflicting results about the relationships between ABO blood groups and Plasmodium infection outcomes in humans. This study examined association between ABO blood group and Plasmodium falciparum (P. falciparum) malaria related outcomes among 1065 malaria suspected febrile patients who attended Dore Baafano Health Center, southern Ethiopia, between December, 2010 and February, 2011. Blood specimens were collected and examined for malaria using Giemsa-staining, while stool specimens were examined for helminth infections using Kato-Katz method. Haemoglobin level and blood group were determined using hemocue machine and antisera hemagglutination test, respectively. Clinical data were also collected for the patients. Among the study participants, the proportion of O, A, B and AB blood groups were 40.1%, 30.1%, 29.0% and 14.3%, respectively, and P. falciparum malaria cases in the corresponding blood groups were 14.8%, 14.0%, 13.4% and 15.7%. The odds of non-severe P. falciparum malaria were not significantly different between individuals of blood group A versus O or B versus O or AB versus O. Mean haemoglobin concentration was significantly lower in P. falciparum infected blood type A individuals compared to P. falciparum infected blood type O (β=-1.25, 95% CI=-2.31 to -0.19) or non-A (β=-1.27, 95% CI=-2.23 to -0.32) individuals. The odds of P. falciparum malaria related anaemia was about three times higher in individuals with blood type A compared to those with blood type O (adjusted OR=2.82, 95% CI=1.05-7.56) or non-A individuals (adjusted OR=2.84, 95% CI=1.15-7.01). However, mean P. falciparum density did not significantly differ among patients according to their blood groups. In conclusion, individuals with blood group A had higher risk of anaemia compared to those with O and non-A phenotypes among P. falciparum malaria patients. However, there is a need to investigate the mechanism.     

Primary infection by Plasmodium falciparum or P. vivax in a cohort of Javanese migrants to Indonesian Papua

The clinical and parasitological characteristics of the first naturally acquired malarial infection have rarely been documented in humans. When 243 migrants from non-endemic Java were followed from the day of their arrival in Indonesian Papua, 217 (89%) were found to become infected with Plasmodium falciparum and/or P. vivax before they were lost to follow-up. The incidence of malarial infection in the children investigated (who were aged 6-10 years) was indistinguishable from that in the adults (aged >20 years), with 1.10 and 1.14 P. falciparum infections/person-year (relative risk=0.97; 95% confidence interval=0.72-1.29) and 1.47 and 1.49 P. vivax infections/person-year (relative risk=0.99; 95% confidence interval=0.72-1.29), respectively. During their first infections, the children had higher P. falciparum parasitaemias than the adults (with geometric means of 1318 and 759 parasites/microl, respectively; P=0.04) but similar P. vivax parasitaemias (with geometric means of 355 and 331 parasites/microl, respectively; P=0.76). At first infection, 56% of the subjects were febrile and 90% complained of symptoms. There were no differences between children and adults with respect to these two parameters, either for P. falciparum or P. vivax. These findings indicate that, with promptly diagnosed and treated uncomplicated malaria, migrant children and adults in north-eastern Indonesian Papua have an equal risk of malarial infection and of disease following their first infections with P. falciparum and P. vivax.     

Mapping malaria transmission in West and Central Africa

We have produced maps of Plasmodium falciparum malaria transmission in West and Central Africa using the Mapping Malaria Risk in Africa (MARA) database comprising all malaria prevalence surveys in these regions that could be geolocated. The 1846 malaria surveys analysed were carried out during different seasons, and were reported using different age groupings of the human population. To allow comparison between these, we used the Garki malaria transmission model to convert the malaria prevalence data at each of the 976 locations sampled to a single estimate of transmission intensity E, making use of a seasonality model based on Normalized Difference Vegetation Index (NDVI), temperature and rainfall data. We fitted a Bayesian geostatistical model to E using further environmental covariates and applied Bayesian kriging to obtain smooth maps of E and hence of age-specific prevalence. The product is the first detailed empirical map of variations in malaria transmission intensity that includes Central Africa. It has been validated by expert opinion and in general confirms known patterns of malaria transmission, providing a baseline against which interventions such as insecticide-treated nets programmes and trends in drug resistance can be evaluated. There is considerable geographical variation in the precision of the model estimates and, in some parts of West Africa, the predictions differ substantially from those of other risk maps. The consequent uncertainties indicate zones where further survey data are needed most urgently. Malaria risk maps based on compilations of heterogeneous survey data are highly sensitive to the analytical methodology.     

Travel histories as risk factors in the analysis of urban malaria in Colombia

Self-reported travel histories were used in a case-control study to determine whether movement of local residents to neighboring endemic areas was a risk factor for malaria in the town of Quibdo, Colombia. Multivariate analyses showed that among residents of Quibdo, traveling to an endemic area 8-14 days before disease onset was the strongest risk factor for both Plasmodium falciparum (adjusted odds ratio [OR] = 28.96, 95% confidence interval [CI] = 13.9-60.32) and P. vivax (adjusted OR = 14.24, 95% CI = 5.27-38.46) malaria. For P. falciparum, individuals who did not travel outside Quibdo during the 8-14 days before disease onset, but who reported traveling 1-7, 15-21, or 22-30 days before disease onset also had an increased risk of malaria. Conversely, use of protection against mosquitoes was negatively associated with P. falciparum. These results highlight the need for malaria control measures that target mobile populations. A definition of imported malaria that allows distinction of imported from autochthonous cases in Quibdo town is proposed.     

Clinical features of children hospitalized with malaria--a study from Bikaner, northwest India

Severe Plasmodium vivax malaria in adults has been reported from Bikaner (northwestern India) but the reports on children are scanty. This prospective study was done on 303 admitted children of malaria. The diagnosis was done by peripheral blood smear and rapid diagnostic test. Further confirmation of severe P. vivax monoinfection was done by polymerase chain reaction (PCR). The proportion of P. falciparum, P. vivax, and mixed (P. falciparum and P. vivax) infection was 61.01%, 33.99%, and 4.95%, respectively. Severe disease was present in 49.5% (150/303) children with malaria, with the risk greatest among P. vivax monoinfection (63.1% [65/103]) compared with P. falciparum, either alone (42.7% [79/185]; odds ratio [OR] = 2.3 [95% confidence interval (CI) = 1.40-3.76], P = 0.001) or mixed infections (40% [6/15]; OR = 2.57 [95% CI = 0.88-7.48]). In children < 5 years of age, the proportion of severe malaria attributable to P. vivax rose to 67.4% (31/46) compared with 30.4% (14/46) of P. falciparum (OR = 4.7 [95% CI = 2.6-8.6], P < 0.0001) and 2.2% (1/46) of mixed infection (OR = 92 [95% CI = 24.6-339.9], P < 0.0001). The proportion of patients having severe manifestations, which included severe anemia, thrombocytopenia, cerebral malaria, acute respiratory distress syndrome, hepatic dysfunction, renal dysfunction, abnormal bleeding was significantly high in association with P. vivax monoinfection in 0-5 year age group, while the same was significantly high in association with P. falciparum monoinfection in 5-10 year age group. Similarly P. vivax monoinfection had greatest propensity to cause multiorgan dysfunction in 0-5 year age group (34.1% [17/41], P < 0.0001) in comparison to P. falciparum monoinfection, which had similar propensity in 5-10 year age group (36.8% [35/95], P = 0.039). Plasmodium vivax monoinfection was almost equally serious to cause significant mortality in comparison to P. falciparum (case fatality rate of severe P. vivax was 3.9% versus 3.2% of severe P. falciparum malaria; P = 1.0). This study reaffirms the evidence of severe P. vivax malaria in children in Bikaner.     

Performance of two malaria rapid diagnostic tests in febrile adult patients with and without human immunodeficiency virus-1 infection in Blantyre, Malawi

The performance of two histidine-rich protein type-2-based malaria rapid diagnostic tests (mRDTs) was examined in a rural area with a high prevalence of malaria and human immunodeficiency virus type-1 (HIV-1) infection in 113 and 445 febrile patients ≥ 15 years of age with and without HIV-1 infection, respectively. Patients were tested for HIV-1 infection by using a standard assay and for Plasmodium falciparum by using two mRDTs and microscopy. When microscopy was used as the gold standard, both mRDTs performed similarly in patients with and without HIV-1 infection: Bioline SD Malaria Antigen P.f, sensitivity 94.4% (95% confidence interval [CI]: 81.3-99.3%) versus 97.1% (95% CI:92.8-99.2%) and specificity 50.6% (95% CI: 39.0-62.2%) versus 47.2% (95% CI: 41.4-53.1%); and ICT diagnostics Malaria Pf, sensitivity 94.4% (95% CI: 81.3-99.3%) versus 97.1% (95% CI: 92.8-99.2%) and specificity 50.6% (95% CI:39.0-62.2%) versus 50.3% (95% CI: 44.4-56.1%). Infection with HIV-1 does not appear to affect the performance of these histidine-rich protein type-2 (HRP-2)-based mRDTs.     

Assessing the Parasight-F test in northeastern Papua,Indonesia, an area of mixed Plasmodium falciparum and Plasmodium vivax transmission

User-friendly, reliable, and inexpensive methods for diagnosing malaria are needed at the primary health care level. During a randomized treatment trial, the Parasight-F test was assessed on days 0, 3, 7, and 28 against standard light microscopy of Giemsa-stained thick blood smears for diagnosing Plasmodium falciparum parasitemia in patients with P. falciparum (n = 84) or P. vivax (n = 59) malaria. The median P. falciparum parasite count on day 0 was 2,373/microL (range = 20-74,432/microL). At the start of treatment, the Parasight-F test had a sensitivity of 95.2% (80 of 84; 95% confidence interval [CI] = 88.2-98.7), and a specificity of 94.9% (56 of 59; 95% CI = 85.8-98.9). On day 7, this test showed false-positive results in 17 (16.3%) of 104 patients (95% CI = 9.8-24.9). The Parasight-F test performed well when compared with light microscopy in detecting P. falciparum parasitemia in patients presenting with clinical malaria. However, the high false-positive rate on day 7 limits its use for patient follow-up.     

Anemia and malaria at different altitudes in the western highlands of Kenya

Malaria associated severe anemia in children is the most important complication of Plasmodium falciparum infection in sub-Saharan Africa. To evaluate anemia and malaria in an area with recurrent malaria epidemics in the western highlands of Kenya, we conducted cross-sectional surveys in four "lowland" (1440-1660 m) and two "highland" (1960 and 2040 m) villages in 2002. Among 1314 subjects randomly selected from all age groups, the overall prevalence of anemia (hemoglobin, Hb < 11 g/dl) was 14% and P. falciparum infection 17%. In children < or =5 years, anemia prevalence ranged from 57% at 1440 m to 11% at 2040 m and correlated with altitude (r = -0.88, P < 0.05). Similarly, P. falciparum prevalence ranged from 31 to 0% and correlated with altitude (r = -0.93, P < 0.01). Malnutrition defined by a body mass index <15th percentile characterized 39% of the population and the hookworm prevalence was 3.9%. In the lowland villages, anemia was most common in children < or =5 years of age (34%) followed by women of childbearing age (16%). A similar pattern was also observed in the highland villages. In these vulnerable populations, hemoglobin concentration was significantly associated with malaria infection, but not with malnutrition or hookworm infestation and comparisons of anemia prevalence between highland and lowland villages revealed that two-thirds of anemia could be attributed to malaria infection. The prevalence of severe anemia (Hb < 8 g/dl) was 1.5%; of these, 90% resided in lowland villages, 70% were under-fives, while 20% were women of childbearing age. In severely anemic subjects, the Hb concentration decreased further with malnutrition (P < 0.05). Anemia was more prevalent in the lowland villages characterized by high prevalence of P. falciparum infection. We conclude that malaria may also be the main cause of anemia in the highland fringe areas of sub-Saharan Africa. Measures that reduce the prevalence of malaria will consequently reduce anemia in both, young children and adult women and the need for blood transfusions associated with the risk of HIV-transmission.