Seroprevalence Of Zika Virus In Selected Regions In Kenya

Abstract

Background: The 2015-2016 Zika virus pandemic in South America stirred worldwide concern by the public and scientific community. This was due to studies linking Zika virus infection to neurological complications such as microcephaly in newborns. Zika virus is principally spread by Aedes mosquito species amongst jungle primates and humans. Evidence for circulation of Zika virus in East Africa necessitates surveillance studies in Kenya to benchmark efforts for monitoring, prevention, and its control. Broad Objective: To establish seroprevalence of Zika virus in selected regions in Kenya using archived serum samples. Study Method: A laboratory-based cross-sectional descriptive study was conducted on 582 adult human sera initially obtained from Nairobi, Eldoret, and Kisumu from 2009 to 2014, and preserved at the University of Nairobi Institute of Tropical and Infectious Diseases laboratories. The study samples were screened for anti-Zika virus antibodies by an IgG-based Enzyme Linked Immunoabsorbent Assay (ELISA). Any sample tested positive by ELISA was confirmed for the presence of specific antibodies to Zika virus by Plaque Reduction Neutralization Test (PRNT). Chi-square or Fisher’s exact test was used to analyse any statistical association between proportional variation of the prevalence of anti-Zika virus antibodies and the study locations (Nairobi, Eldoret, and Kisumu), where sera were originally collected. This was facilitated by STATA for Windows version 11.2 (StataCorp, Texas, USA). Results: Out of 135 sera from Eldoret, 135 sera from Kisumu, and 312 sera from Nairobi screened by ELISA, 5 returned positive results, 2 were from Kisumu and 3 from Nairobi. One of the two positive sera by ELISA from Kisumu tested positive for anti-Zika virus antibodies as confirmed by Zika virus PRNT, while 3 positive sera by ELISA from Nairobi, returned positive results for dengue virus as confirmed by Dengue virus PRNT. There was no statistical association between the prevalence of anti-Zika virus antibodies and the study locations (Fisher’s exact test P value=0.232). Conclusion: There was evidence of low previous exposure to Zika virus in the study population. Of the three regions in Kenya where sera for this study were obtained, only Kisumu County had one case of previous exposure to Zika virus. Epidemiological changes which might have taken place since 2013 when the sample was first collected necessitates further surveillance studies to update the country regarding the seroprevalence of Zika virus.