Prevalence of Plasmodium falciparum infection in asymptomatic rural Gabonese populations.

BACKGROUND: Malaria may be perennial or epidemic in sub-Saharan Africa, and its transmission may be stable or unstable, depending on the region. The prevalence of asymptomatic Plasmodium falciparum carriage is poorly documented in Gabon. A large survey of P. falciparum infection was conducted in asymptomatic individuals living in rural Gabon. METHODS: Two hundred and twenty-two villages were randomly selected in the nine administrative regions. With the participants' informed consent, blood samples were collected for thick and thin blood film examination after 20% Giemsa staining. Prevalence rates were calculated per village, per region and per ecosystem, and nationwide. Demographic risk factors were identified with STATA software version 9.0. Significance was assumed at p < 0.05. RESULTS AND DISCUSSION: The prevalence of P. falciparum in adults was 6.2% (269/4342) nationwide, with a maximum of 37.2% in one village; a linear decrease was observed with increasing age (p = 0.045). Only 5% of the 399 children from forest areas tested positive. The prevalence was significantly higher in forest areas (7%) than in savannah (4%) and lakeland (2.5%). Within the forest region, the prevalence was significantly higher in forest grassland (10.9%) than in the mountain forest (3.5%), interior forest (6.8%) and north-eastern forest (4.5%). CONCLUSION: Plasmodium falciparum carriage remains high among adults in rural Gabon. Control measures must be adapted to the region and ecosystem. Routine treatment of asymptomatic individuals should be considered.