Seroepidemiological reconstruction of long-term chikungunya virus circulation in Burkina Faso and Gabon.

Chikungunya virus (CHIKV) is a major public health concern worldwide. However, infection levels are rarely known, especially in Africa. We recruited individuals from Ouagadougou, Burkina Faso and Lambaréné, Gabon (age range: 1-55), tested their blood for CHIKV antibodies and used serocatalytic models to reconstruct epidemiological histories. In Ouagadougou, 291/999 (29.1%) individuals were seropositive, ranging from 2% among those <10y to 66% in those 40-55y. We estimated there were 7 outbreaks since the 1970s but none since 2001 resulting in 600,000 infections in the city, none of which were reported. However, we could not definitively conclude whether infections were due to CHIKV or o'nyong-nyong, another alphavirus. In Lambaréné, 117/427 (27%) participants were seropositive. Our model identified a single outbreak sometime since 2007, consistent with the only reported CHIKV outbreak in the country. These findings suggest sporadic outbreaks in these settings and that the burden remains undetected or incorrectly attributed.