title: Seroprevalence and risk factors of chikungunya virus infection in Mayotte, Indian Ocean, 2005-2006: a population-based survey.
abstract: BACKGROUND
  Since 2006, Chikungunya virus (CHIKV) has re-emerged as an important pathogen of global concern. However, individual and household factors associated with the acquisition and the magnitude of clinically silent CHIKV infections remain poorly understood. In this present study, we aimed to investigate the seroprevalence, estimate the proportion of symptomatic illness and identify the risk factors for CHIKV infection in the primo-exposed population of Mayotte. METHODS/ PRINCIPAL FINDINGS: We conducted a household-based cross sectional serosurvey in Mayotte in November and December 2006 using complex multistage cluster sampling. To produce the results representative of the island population aged 2 years or older, sample data were adjusted with sample weights. Explanatory and multiple logistic regression analyses were performed to investigate associations between CHIKV infection seropositivity (presence of IgM and/or IgG to CHIKV by enzyme-linked immunoabsorbent assay) and risk factors. A total of 1154 individuals were analyzed. The overall seroprevalence of CHIKV infection was 37.2% (95% CI = 33.9-40.5), 318 (72.3%) of the seropositive participants reported symptoms consistent with a CHIKV infection during the epidemic period. Risk factors for CHIKV seropositivity among adults (aged 15 years and older) were male gender, low socioeconomic index, schooling < or = 6 years and living in makeshift housing.
  
  
  CONCLUSIONS
  Our findings indicate that roughly one out of four CHIKV infections is asymptomatic. Conditions associated with poverty may be considered as critical in CHIKV acquisition. Thus, these conditions should be taken into account in the development of future prevention strategies of CHIKV disease.
authors: Institut de veille sanitaire, Cellule Interrégionale d'Epidémiologie Réunion et Mayotte, Saint-Denis, La Réunion, France. daouda.sissoko@sante.gouv.fr
authors: Daouda
authors: D
authors: Sissoko
authors: Amrat
authors: A
authors: Moendandze
authors: Denis
authors: D
authors: Malvy
authors: Claude
authors: C
authors: Giry
authors: Khaled
authors: K
authors: Ezzedine
authors: Jean Louis
authors: JL
authors: Solet
authors: Vincent
authors: V
authors: Pierre
mesh_terms: D000293:Adolescent; D018354:Alphavirus Infections / Q000175:diagnosis / Q000453:epidemiology*; D019352:Censuses; D002646:Chikungunya virus; D002648:Child; D017507:Comoros / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003710:Demography; D003937:Diagnosis, Differential; D005191:Family Characteristics; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D011159:Population Surveillance; D015995:Prevalence; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D012959:Socioeconomic Factors