Temporal Trends of Dengue Seroprevalence among Children in Coastal Kenya, 1998–2018: a Longitudinal Cohort Study

Serosurveys suggest widespread dengue virus (DENV) transmission in Africa but there is limited information on the temporal patterns of exposure. Here, we estimated the prevalence and incidence of DENV infections in coastal Kenya over a 20-year period (1998–2018). Sera (n=8038) obtained annually from a longitudinal cohort of 1847 children aged 15 years and below were screened for anti-DENV IgG antibodies. Anti-DENV IgG seroprevalence increased with age and peaked during outbreak years. Among 1354 children who were seronegative at recruitment, we observed an overall incidence (seroconversion) rate of 129.5 (95% CI 118.7–141.4) DENV infections per 1000 person-years. The highest incidence was observed in 2013 at 520 infections per 1000 person-years (95% CI 443.6–610.2) coinciding with a large DENV outbreak in coastal Kenya. Our data suggest long-term DENV exposure among children in coastal Kenya highlighting an urgent need for clinical surveillance to determine the associated health burden in this setting.