Temporal trends of dengue exposure among children in coastal Kenya

Abstract Background Serosurveys suggest widespread dengue virus (DENV) transmission in Africa but there is limited information on the temporal patterns of exposure. Methods Using repeated cross-sectional serosurvey data, we estimated the prevalence and incidence of DENV infections in coastal Kenya over 20 years (1998–2018). Stored sera ( n = 8025), collected annually from an open longitudinal cohort of 1834 children aged 15 years and below, were screened for anti-DENV IgG antibodies. Results We show that, of 8025 samples, 2287 (28.5%, 95% CI 27.5–29.5%) were seropositive for DENV IgG antibodies. Seroprevalence increased with age, from 2% among children aged below 1 year to 40% among those aged 9 to 10 years, and peaked during outbreak years. Among 1343 children who were seronegative at recruitment, the overall incidence (seroconversion) rate was 111.5 DENV infections per 1000 person-years (95% CI 102.5–121.2). The highest incidence occurred in 2013 at 439.7 infections per 1000 person-years (95% CI 375.1–515.5), coinciding with a large outbreak in coastal Kenya. Conclusions Our findings suggest long-term DENV exposure among children in coastal Kenya and highlight an urgent need for clinical surveillance to determine the associated health burden.