Seroprevalence of Anti-Chikungunya Virus Antibodies in Children and Adults in Managua, Nicaragua, After the First Chikungunya Epidemic, 2014-2015

Chikungunya is a viral disease transmitted by Aedes aegypti and Ae. albopictus mosquitoes. In late 2013, chikungunya virus (CHIKV) was introduced into the Caribbean island of St. Martin. Since then, approximately 2 million chikungunya cases have been reported by the Pan American Health Organization, and most countries in the Americas report autochthonous transmission of CHIKV. In Nicaragua, the first imported case was described in July 2014 and the first autochthonous case in September 2014. Here, we conducted two studies to analyze the seroprevalence of anti-CHIKV antibodies after the first chikungunya epidemic in a community-based cohort study (ages 2–14 years) and in a cross-sectional survey of persons aged ≥15 years in the same area of Managua, Nicaragua. Routine annual serum samples collected from 3,362 cohort participants in March/April 2014 and 2015, and 848 age-stratified samples collected from persons ≥15 years old at the end of May-beginning of June 2015 were used to estimate the seroprevalence of anti-CHIKV antibodies after the first epidemic (October 2014 to February 2015 in the study population). Using an Inhibition ELISA assay that measures total anti-CHIKV antibodies, the seroprevalence was significantly higher in those aged ≥15 (13.1% (95%CI: 10.9, 15.5)) than in the pediatric population (6.1% (95%CI: 5.3, 6.9)). The proportion of inapparent infections was 58.3% (95%CI: 51.5, 65.1) in children and 64.9% (95%CI: 55.2, 73.7) in the ≥15 study population. We identified age, water availability, household size, and socioeconomic status as factors associated with the presence of anti-CHIKV antibodies. Overall, this is the first report of CHIKV seropositivity in continental Latin America and provides useful information for public health authorities in the region.Author Summary: Chikungunya is a viral disease primarily characterized by high fever and joint pain. Chikungunya virus (CHIKV) is transmitted by infected Aedes aegypti and Ae. albopictus mosquitos. Although chikungunya was first described in 1952 and CHIKV has circulated in parts of Africa and Asia, since then, it was not introduced into the Americas until late 2013. Chikungunya poses a threat in tropical countries where the vector mosquitoes reside and in particular in CHIKV-naïve populations. In this study, we aimed to explore the dissemination of CHIKV through the first epidemic in Nicaragua and evaluate possible factors associated with infection. By analyzing the sera of two study populations, pediatric (2–14 years old) and ≥15 years participants, for anti-CHIKV antibodies, we determined who was infected during the first outbreak in Nicaragua. The seroprevalence of anti-CHIKV antibodies in the pediatric and ≥15 year-old study populations was 6.1% and 13.1%, respectively. Furthermore, using a demographic/household survey, we found that age, water availability, household size, and socioeconomic status were associated with CHIKV seropositivity. In conclusion, this study indicates the level of protective immunity the population has developed and can help government institutions develop intervention strategies.