Assessing the Serological Antibody Repertoire to Flaviviruses in the Endemic Population of the Zika Forest in Uganda

While the Zika virus has been suspected to cause complications in newborns of women infected during pregnancy, it has circulated in Africa for more --than half a century without any reported cases of microcephaly in children. To assess the prevalence of Zika infections in the Zika forest region we collected human sera samples from 81 people (17–56 years old), who live in Zika forest region, Entebbe, Uganda in 2016, and included both individuals hospitalized with acute febrile illness, as well as health individuals. Elisa assays were used to profile the IgM, IgG serological repertoire to Zika, Dengue 1-4 (DENV1-4) and Yellow Fever (YFV) viruses. We found that 17 individuals (21%) were positive for Zika, 7 of which were hospitalized with acute infection. The hospitalized patients had overall higher antibody titers to Zika. There also were serologically positive samples for: DENV1 n=11 (13.5%); DENV2 n=9 (11%), DENV3 n=4 (5%); DENV 4 n=4 (5%). 11 subjects (13.5%) were positive for YFV. Overall, 49% of the subjects had antibodies to at least one of these Flaviviruses, and 17% had antibodies to two or more Flaviviruses. While serological responses cannot accurately diagnose the specific Flavirvirus infections in these individuals due to significant cross reactivity within this viruses our data suggests that Flavivirus infections are very common in the Zika forest region. While a recent study reported that previous dengue infections may cause antibody dependant enhancement upon subsequent Zika infection, our data suggests that the Zika forest region in which many different Flaviviruses have been circulating for over 50 years may an important region to study such effects in the human population.