Clinical Forms of Chikungunya in Gabon, 2010

Chikungunya fever (CHIK) is a disease caused by a virus transmitted to humans by infected mosquitos. The virus is responsible for multiple outbreaks in tropical and temperate areas worldwide, and is now a global concern. Clinical and biological features of the disease are poorly described, especially in Africa, where the disease is neglected because it is considered benign. During a recent CHIK outbreak that occurred in southeast Gabon, we prospectively studied clinical and biological features of 270 virologically confirmed cases. Fever and arthralgias were the predominant symptoms. Furthermore, variable and distinct clinical pictures including pure febrile, pure arthralgic and unusual forms (neither fever nor arthralgias) were detected. No severe forms or deaths were reported. These findings suggest that, during CHIK epidemics, some patients may not have classical symptoms (fever and arthralgias). Local surveillance is needed to detect any changes in the pathogenicity of this virus

No Clinical or Biological Difference between Chikungunya and Dengue Fever during the 2010 Gabonese Outbreak

Chikungunya (CHIKV) and Dengue (DENV) viruses, both arboviruses, have caused multiple outbreaks worldwide. Their clinical features are poorly described in Africa and there is no comparative study, although Chikungunya is considered as a dengue-like disease. We conducted a comparative study of clinical and biological data from CHIKV and DENV positive patients during the 2010 Gabonese outbreak. Patients consulting with general symptoms and having laboratory confirmation for CHIKV or DENV were included. Clinical and biological data were recorded. Statistical analyses were performed using Epi Info. A P value < 0.05 was considered significant. In all, 270 CHIKV+, 53 DENV+ and 20 co-infected patients were included in the study. Headaches, hemorrhage, leukopenia and lymphopenia were significantly (P respectively 0.01, 0.001, 0.02 and 0.001) more frequent in DENV+ patients than in CHIKV+. There was no additive effect of the two viruses. These clinical and hematological disorders are non specific and cannot assist for the differential diagnosis. These diseases are clinically indistinguishable, and need for laboratory confirmation

Phylogenic relationships of DENV-2 strains circulating in Gabon between 2007 and 2010.

<p>The DENV-2 sequence from patient with hemorrhagic sign ends with ‘h’ (for hemorrhagic sign).</p

Phylogenic relationships of DENV-1 strains circulating in Gabon between 2009 and 2010.

<p>Phylogenic relationships of DENV-1 strains circulating in Gabon between 2009 and 2010.</p

Phylogenic relationships of the DENV-3 strain circulating in Gabon during the 2010 Franceville outbreak.

<p>Phylogenic relationships of the DENV-3 strain circulating in Gabon during the 2010 Franceville outbreak.</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

Mean prevalence according to the age groups.

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