Clinical forms of chikungunya in Gabon, 2010

Abstract

Background: Chikungunya virus (CHIKV) has caused multiple outbreaks in tropical and temperate areas worldwide, but the clinical and biological features of this disease are poorly described, particularly in Africa. We report a prospective study of clinical and biological features during an outbreak that occurred in Franceville, Gabon in 2010.

Methodology/principal findings: We collected, in suspect cases (individuals presenting with at least one of the following symptoms or signs: fever, arthralgias, myalgias, headaches, rash, fatigue, nausea, vomiting, diarrhea, bleeding, or jaundice), blood samples, demographic and clinical characteristics and outcome. Hematological and biochemical tests, blood smears for malaria parasites and quantitative PCR for CHIKV then dengue virus were performed. CHIKV+ patients with concomitant malaria and/or dengue were excluded from the study. From May to July 2010, data on 270 laboratory-confirmed CHIK patients were recorded. Fever and arthralgias were reported by respectively 85% and 90% of patients, while myalgias, rash and hemorrhage were noted in 73%, 42% and 2% of patients. The patients were grouped into 4 clinical categories depending on the existence of fever and/or joint pain. On this basis, mixed forms accounted for 78.5% of cases, arthralgic forms 12.6%, febrile forms 6.7% and unusual forms (without fever and arthralgias) 2.2%. No cases of organ failure or death were reported. Elevated liver enzyme and creatinine levels, anemia and lymphocytopenia were the predominant biological abnormalities, and lymphocytopenia was more severe in patients with high viral loads (p = 0.01).

Conclusions/significance: During CHIK epidemics, some patients may not have classical symptoms. The existence of unusual forms and the absence of severe forms of CHIK call for surveillance to detect any change in pathogenicity.

Figure 1. Map of Gabon, and location of the different Chikungunya outbreaks from 2007 to 2010.

Figure 2. Distribution of Chikungunya confirmed cases according to the date of onset, in Franceville, 2010.

Figure 3. Algorithm for cases selection.

Figure 4. Frequency of the main symptoms in patients with Chikungunya during the 2010 Franceville outbreak.

Figure 5. Photographs of clinical manifestations in CHIKV+ patients during the 2010 outbreak in Franceville, Gabon.

A: Swelling of the ankles and feet in a 43-year-old woman. B: Resolutive maculopapular rash of the arms in a 41-year-old man. C: Bullous vesicles on the thigh of a 3-year-old child. D: Rash with edema of the face in a 16-year-old girl.

Figure 6. Distribution of clinical forms.

A: Distribution of the four clinical forms. B: Distribution of clinical forms according to the period of the outbreak.