Estimating Chikungunya prevalence in La Réunion Island outbreak by serosurveys: Two methods for two critical times of the epidemic
Autor(es): Gérardin Patrick, Guernier Vanina, Perrau Joëlle, Fianu Adrian, Le Roux Karin, Grivard Philippe, Michault Alain, de Lamballerie Xavier, Flahault Antoine, Favier François
Resumo: Chikungunya virus (CHIKV) caused a major two-wave seventeen-month-long outbreak in La Réunion Isl- in 2005-2006. The aim of this study was to refine clinical estimates provided by a regional surveillance-system using a two-stage serological assessment as gold st-ard. Two serosurveys were implemented: first, a rapid survey using stored sera of pregnant women, in order to assess the attack rate at the epidemic upsurge (s1, February 2006; n = 888); second, a population-based survey among a r-om sample of the community, to assess the herd immunity in the post-epidemic era (s2, October 2006; n = 2442). Sera were screened for anti-CHIKV specific antibodies (IgM - IgG in s1, IgG only in s2) using enzyme-linked immunosorbent assays. Seroprevalence rates were compared to clinical estimates of attack rates. In s1, 18.2% of the pregnant women were tested positive for CHIKV specific antibodies (13.8% for both IgM - IgG, 4.3% for IgM, 0.1% for IgG only) which provided a congruent estimate with the 16.5% attack rate calculated from the surveillance-system. In s2, the seroprevalence in community was estimated to 38.2% (95% CI, 35.9 to 40.6%). Extrapolations of seroprevalence rates led to estimate, at 143,000 - at 300,000 (95% CI, 283,000 to 320,000), the number of people infected in s1 - in s2, respectively. In comparison, the surveillance-system estimated at 130,000 - 266,000 the number of people infected for the same periods. A rapid serosurvey in pregnant women can be helpful to assess the attack rate when large seroprevalence studies cannot be done. On the other h-, a population-based serosurvey is useful to refine the estimate when clinical diagnosis underestimates it. Our findings give valuable insights to assess the herd immunity along the course of epidemics.
Imprenta: BMC Infectious Diseases, v. 8, p. 99, 2008
Identificador do objeto digital: 10.1186/1471-2334-8-99
Descritores: Chikungunya virus - Pathogenesis ; Chikungunya virus - Proteins ; Chikungunya virus - Antibodies ; Chikungunya virus - Viral infections ; Chikungunya virus - Serological diagnosis ; Chikungunya Virus - Virus ; Chikungunya virus - Epidemic ; Chikungunya virus - Epidemiology ; Chikungunya virus - Immunology ; Chikungunya virus - Public health
Data de publicação: 2008
