The role of environmental and individual factors in the social epidemiology of chikungunya disease on Mayotte Island.

This article examines the role of environmental and individual factors in the social epidemiology of chikungunya disease on the island of Mayotte (South-western Indian Ocean). In an epidemic setting, an interdisciplinary study combining interviews, observations, and serological tests was conducted to: (1) estimate the frequency and social distribution of chikungunya disease and (2) identify its principal cognitive, behavioral, and environmental determinants within a stratified random sample of the Mayotte population (n=888). Semi-parametric tests and multiple correspondence analyses were used to describe the statistical relationships between the different classes of variables examined in this study and the presence of antibodies attributable to chikungunya. These analyses highlighted differences between two main types of populations: one more autochthonous, more urban and better educated population, which shared 'legitimate' representations of the disease-from a biomedical viewpoint; and the other more migrant, more suburban, and more deprived, which is characterized by folk theories of chikungunya virus infection. Moreover, a series of logistic regression models revealed that social disparities in the distribution of virus infection were primarily structured by the housing conditions and cognitive representations of the disease held by the participants. These results suggest that environmental and individual factors are equally crucial in epidemic settings, and that they could explain, to a considerable extent, the social differences observed in morbidity associated with recent emerging infectious diseases in tropical countries.

Retrospective survey of Chikungunya disease in Réunion Island hospital staff.

Réunion Island (Indian Ocean) has been suffering from its first known Chikungunya virus (CHIKV) epidemic since February 2005. To achieve a better understanding of the disease, a questionnaire was drawn up for hospital staff members and their household. CHIKV infected about one-third of the studied population, the proportion increasing with age and being higher in women. Presence of a garden was associated with CHIKV infection. The geographical distribution of cases was concordant with insect vector Aedes albopictus distribution. The main clinical signs were arthralgia and fever. The disease evolved towards full recovery in 34.4% of cases, a relapse in 55.6%, or a chronic form in 10%. Paracetamol was used as a painkiller in 95% of cases, sometimes associated with non-steroidal anti-inflammatory drugs, corticoids, or traditional herbal medicine. The survey provided valuable information on the factors that favour transmission, the clinical signs, the importance of relapses and the therapies used.