Abstract. Anemia during childhood remains a major public health challenge in sub-Saharan Africa. To determine the prevalence of and the main risk factors for anemia in young children, we conducted a longitudinal survey in Ebolowa in southern Cameroon. Children were enrolled in two cohorts and followed during a three-year period: the first cohort was composed of 122 children from 0 to 36 months of age and the second cohort was composed of 84 children from 24 to 60 months of age. The two cohorts were followed weekly for symptomatic malaria, monthly for both symptomatic and asymptomatic malaria, and every six months for hematologic data; the children were grouped into six-month age groups. The prevalence of anemia (hemoglobin [Hb] level Ͻ 11 g/dl) was the highest in the sixmonth-old age group (47%) and the age-related evolution clearly showed a decrease in the prevalence from three years of age. Thus, 42% of the children less than three years of age were anemic, while 21% of the children between three and five years of age were anemic. The lowest mean Ϯ SD Hb content (10.7 Ϯ 2.1 g/dl) was observed in the six-month-old children and a regular improvement in the Hb level occurred from six months to three years of age. A stabilization was observed at a level of approximately 12 g/dl. At any age, there was no difference in mean Hb levels between children with AS and AA Hb genotypes. Hookworm infection was diagnosed in two children in the study population. Results of a multivariate analysis showed that placental malaria infection was the strongest risk factor for anemia in the six-month-old children (odds ratio [OR] ϭ 3.6; 95% confidence interval [CI] ϭ 1.1-12.3) and was independent of the frequency of parasitemia, parasitemia at the time of Hb measurement, or microcytosis. In the one-year-old age group, microcytosis was a significant factor related to anemia (OR ϭ 2.8, 95% CI ϭ 1-7.8) pointing out the role of iron deficiency at this age. Parasitemia at the time of Hb measurement was significantly associated with anemia in all age groups (except in 54-and 60-month-old groups). Strategies to decrease the prevalence of anemia in young children in southern Cameroon should include chemoprophylaxis for pregnant women, prevention of acquired malaria infection in both pregnancy and infancy, and prevention of nutritional iron deficiency.Anemia impairs normal development in children and it constitutes a major public health problem in young children in the developing world with wide social and economic implications. Thus, decreased physical exercise tolerance and intellectual performance have been associated with mild anemia, which may lead to a slowdown of growth in children. 1, 2In sub-Saharan Africa in children less than five years of age, the prevalence of anemia varies from 43% in Zaire to 74% in Tanzania. 3, 4 Its etiology in tropical countries is multifactorial: thus, the most important risk factors need to be identified for prevention strategy. Anemia is commonly associated with nutritional deficiencies such as iron defic...

SummaryQuantitatively assessing the impact of naturally occurring transmission-blocking (TB) immunity on malaria parasite sporogonic development may provide a useful interpretation of the underlying mechanisms. Here, we compare the effects of plasma derived from 23 naturally infected gametocyte carriers (OWN) with plasma from donors without previous malaria exposure (AB) on the early sporogonic development of Plasmodium falciparum in Anopheles gambiae. Reduced parasite development efficiency was associated with mosquitoes taking a blood meal mixed with the gametocyte carriers' own plasma, whereas replacing autologous plasma with non-immune resulted in the highest level of parasite survival. Seven days after an infective blood meal, 39.1% of the gametocyte carriers' plasma tested showed TB activity as only a few macrogametocytes ingested along with immune plasma ended up as ookinetes but subsequent development was blocked in the presence of immune plasma. In other experiments (60.9%), the effective number of parasites declined dramatically from one developmental stage to the next, and resulted in an infection rate that was two-fold lower in OWN than in AB infection group. These findings are in agreement with those in other reports and go further by quantitatively examining at which transition stages TB immunity exerts its action. The transitions from macrogametocytes to gamete/zygote and from gamete/zygote to ookinete were identified as main targets. However, the net contribution of host plasma factors to these interstage parasite reductions was low (5-20%), suggesting that irrespective of the host plasma factors, mosquito factors might also lower the survival level of parasites during the early sporogonic development.

BackgroundLoiasis is a parasitic infection endemic in the African rain forest caused by the filarial nematode Loa loa. Loiasis can be co-endemic with onchocerciasis and/or lymphatic filariasis. Ivermectin, the drug used in the control of these diseases, can induce serious adverse reactions in patients with high L loa microfilaraemia (LLM). A drug is needed which can lower LLM below the level that represents a risk so that ivermectin mass treatment to support onchocerciasis and lymphatic filariasis elimination can be implemented safely.MethodologySixty men and women from a loiasis endemic area in Cameroon were randomized after stratification by screening LLM (≤30000, 30001–50000, >50000) to three treatment arms: two doses albendazole followed by 4 doses matching placebo (n = 20), six doses albendazole (n = 20) albendazole or 6 doses matching placebo (n = 20) administered every two months. LLM was measured before each treatment and 14, 18, 21 and 24 months after the first treatment. Monitoring for adverse events occurred three and seven days as well as 2 months after each treatment.Principal FindingsNone of the adverse events recorded were considered treatment related. The percentages of participants with ≥ 50% decrease in LLM from pre-treatment for ≥ 4 months were 53%, 17% and 11% in the 6-dose, 2-dose and placebo treatment arms, respectively. The difference between the 6-dose and the placebo arm was significant (p = 0.01). The percentages of participants with LLM < 8100 mf/ml for ≥4 months were 21%, 11% and 0% in the 6-dose, 2-dose and placebo treatment arms, respectively.Conclusions/ SignificanceThe 6-dose regimen reduced LLM significantly, but the reduction was insufficient to eliminate the risk of severe and/or serious adverse reactions during ivermectin mass drug administration in loiasis co-endemic areas.

SummaryWe conducted parasitological and entomological malaria surveys among the population of Mengang district in southern Cameroon to analyse the relationship between malaria transmission intensity and malaria morbidity. We investigated two adjacent areas which differ 10-fold in transmission intensity [annual entomological inoculation rate (EIR) 17 vs. 170], but have very similar Plasmodium falciparum malariometric profiles with parasite prevalences of 58 vs. 64%, high parasitaemia prevalences (> 1000 parasites/ll) of 15 vs. 16% and the same morbidity of 0.17-0.5 attacks/person/year. Plasmodium malariae prevalence was 14 vs. 16%. One possible explanation is that the similarity of the duration of the short and high transmission seasons in both areas is equally, if not more, significant for parasitological and clinical profiles as the annual EIR. We discuss the relationships between variations in transmission levels, parasitaemia and clinical incidence, and draw parallels to similar situations elsewhere.