Risk factors for Zaire ebolavirus--specific IgG in rural Gabonese populations.

BACKGROUND: In Gabon, several Ebolavirus outbreaks have occurred exclusively in the northeastern region. We conducted a large serosurvey to identify areas and populations at risk and potential demographic, clinical, and behavioral risk factors. METHODS: Blood samples and clinical and sociodemographic data were collected from 4349 adults and 362 children in a random sample of 220 villages in the 9 provinces of Gabon. An enzyme-linked immunosorbent assay was used to detect Zaire ebolavirus (ZEBOV)-specific IgG, and thin blood smears were used to detect parasites. Logistic regression was implemented using Stata software (Stata), and a probability level of <.05 was considered to be statistically significant. RESULTS: The prevalence of ZEBOV-specific IgG was 15.3% overall, increasing to 32.4% (P< .001) in forest areas. No sociodemographic risk factors were found, but the antibody prevalence increased linearly up to 20 years of age. Chronic arthralgia and amicrofilaremia were the only factors associated with ZEBOV seropositivity. CONCLUSIONS: These findings confirm the endemicity of ZEBOV in Gabon and its link to the ecosystem. Human antibody positivity would appear to be to the result of exposure to contaminated fruits

Attitudes and behaviors concerning malaria.

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

Baseline Characteristics of the study subjects.

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

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

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

Stepwise multivariate logistic regression analysis of significant variables.

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

Nucleotide primers used in STEVOR gene amplification.

<p>Nucleotide primers used in STEVOR gene amplification.</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