Seroprevalence of Dengue, Chikungunya and Rift Valley fever virus IgG antibodies in Kenyan blood donors

Dengue virus (DENV), chikungunya virus (CHIKV) and Rift Valley fever virus (RVFV) continue to cause recurrent outbreaks in East Africa, yet contemporary national seroprevalence data remain absent. We used a new in-house multiplex immunoassay (arbo-plex MIA) to estimate the national burden of arboviral exposure across Kenya. We validated the arbo-plex MIA against Foci Reduction Neutralization Test (FRNT) and commercial IgG ELISAs. Subsequently, we tested 11,124 blood donor samples, collected nationwide from individuals aged 15-64 years in 2020 /2021, for anti-IgG antibodies to DENV, CHIKV and RVFV. Seroprevalence estimates were stratified by age, sex and region. In 2020/21, crude national seroprevalence was 20.9% for DENV, 24% for CHIKV and 4.2% for RVFV while Bayesian population-weighted and test-performance-adjusted national seroprevalence was 7.6% for DENV, 18.4% for CHIKV and 3.1% for RVFV. Seropositivity increased with age for all viruses. The highest seroprevalence for DENV (58.2%) and CHIKV (32.8%) occurred in the Coast region, while RVFV burden was greatest in North-Eastern (5.3%). The arbo-plex MIA proved to be a sensitive, specific and operationally efficient platform for integrated arbovirus surveillance. Overall, the findings suggest that approximately one in five people in Kenya had evidence of prior CHIKV exposure by 2020/21, highlighting widespread transmission and a potentially substantial but under-recognized public health burden that warrants urgent attention. In contrast, DENV and RVFV appear more geographically focal, with persistent but clustered transmission patterns, suggesting that targeted surveillance and region-specific control strategies may be more appropriate for their containment.