Seroprevalencia y tasa de ataque clínica por chikungunya en Nicaragua, 2014-2015

OBJECTIVE. Estimate seroprevalence, clinical case rate, and proportion of subclinical infections from chikungunya. METHODS. A cross-sectional study was conducted in October 2015 at 39 sites distributed across Nicaragua. Demographic and clinical information was compiled through a personal survey. Blood samples were collected to detect chikungunya antibodies using the ELISA inhibition method developed by Nicaragua’s National Diagnostic and Reference Center. Results were analyzed using generalized linear models and multilevel Poisson models. RESULTS. A total of 11 722 participants aged >2 years were enrolled and 11 280 samples were processed. National seroprevalence was 32.8% (95% CI [95% confidence interval]: 31.9-33.6), with a clinical case rate of 26.5% (95% CI: 25.7-27.3) and a proportion of subclinical infections of 19.1% (95% CI: 17.8-20.4). Seroprevalence varied among the 39 sites and was greater at sites with higher vector infestation indices. Individually, seroprevalence was higher in participants aged >11 years. CONCLUSION. Since its introduction, this is the first study on chikungunya seroprevalence in continental Latin America to determine national prevalence, clinical case rate, and proportion of subclinical infections. The study model, employing broad community participation and leadership by the Ministry of Health of Nicaragua, can be an example for conducting similar studies in the region.