Comparative antibody responses against three antimalarial vaccine candidate antigens from urban and rural exposed individuals in Gabon

International audienc

Baseline Characteristics of the study subjects.

<p>Baseline Characteristics of the study subjects.</p

Global <i>P</i>. <i>falciparum</i> prevalences in Dienga.

<p>Global <i>P</i>. <i>falciparum</i> prevalences in Dienga.</p

Stepwise multivariate logistic regression analysis of significant variables.

<p>Stepwise multivariate logistic regression analysis of significant variables.</p

Marked Rise in the Prevalence of Asymptomatic <i>Plasmodium falciparum</i> Infection in Rural Gabon

<div><p>Control strategies implemented a decade ago led to a marked reduction in the prevalence of malaria in many countries. In Dienga, southeastern Gabon, the prevalence of microscopic <i>P</i>. <i>falciparum</i> infection was 7% in 2003, close to the pre-elimination threshold of 5%. The aim of this work was to determine the prevalence of <i>P</i>. <i>falciparum</i> infection in the same community a decade later. A cohort of 370 individuals aged from 3 to 85 years living in Dienga was investigated for <i>P</i>. <i>falciparum</i> infection; during six passages (P) in 15-month period. Demographic data were collected, along with behaviors and attitudes towards malaria. <i>Plasmodium</i> infection was diagnosed by microscopy (ME), followed by PCR to detect submicroscopic infection. The prevalence of <i>P</i>. <i>falciparum</i> infection in P1, P2, P3, P4, P5 and P6 was respectively 43.5% (25.1% ME+, 18.4% PCR+); 40.9% (27.0% ME+, 13.9% PCR+), 52.7% (26.1% ME+, 26.6% PCR+); 34.1% (14.1% ME+, 20% PCR+), 57.7% (25.4.% ME+, 32.3% PCR+); and 46.2% (21.4% ME+, 24.8% PCR+) with an overall average of 45.9% (95%CI [37.0–54.7], 23.2% ME+ and 22.7% PCR+). P4 and P5 prevalences were statically different throughout the six passages. Microscopic prevalence was significantly higher than that observed ten years ago (23% [n = 370] vs 7% [n = 323], p < 0.001). Asymptomatic infections were the most frequent (96%). Gametocytes were detected in levels ranging from 5.9% to 13.9%. Insecticide-treated nets, indoor residual insecticides, and self-medication were used by respectively 33.2% (95%CI [29.0–37.4]), 17.7% (95%CI [15.5–19.9]) and 12.1% (95%CI [10.6–13.6]) of the study population. A near-threefold increase in <i>P</i>. <i>falciparum</i> infection has been observed in a rural area of southeastern Gabon during a 10-year period. Most infections were asymptomatic, but these subjects likely represent a parasite reservoir. These findings call for urgent reinforcement of preventive measures.</p></div

Attitudes and behaviors concerning malaria.

<p>Attitudes and behaviors concerning malaria.</p

Mean prevalence according to the age groups.

<p><b>*</b> Significant difference between the prevalence of males obtained by PCR and that observed among females.</p

Mean prevalence according to the age groups.

<p><b>*</b> Significant difference between the prevalence of individuals higher than 18years and other groups.</p