IgG-Antibody Seroprevalence of West Nile Virus among Blood Donors in Nairobi and Nakuru Regional Blood Transfusion Testing Centres in Kenya

Abstract

West Nile Virus (WNV) was first discovered in Africa in 1937 and is transmitted by mosquitoes mainly of the Culex species. It can also be spread through direct contact with the blood or tissue(s) of infected animals. The natural hosts for WNV are the birds. Infection with the virus is associated with serious neurological disorders in man. Twenty percent of people who develop illness have relatively mild disease with symptoms that include fever, headache, body aches, nausea and vomiting as well as swollen glands, skin rash on the chest, stomach and back. Symptoms may be experienced for a few days or weeks or even months while over 80% of those infected may not show any symptoms. In rare cases WNV results to encephalitis leading to death. There is no known vaccine against WNV virus for humans. The main objective of this study was to determine the sero-prevalence of WNV among blood donors in Nairobi and Nakuru Regional blood transfusion testing centers in Kenya. To achieve this objective, a cross sectional study was carried out in two Regional Blood Transfusion Centers (RBTCs) which are based in Nairobi and Nakuru. These two centers were associated with possible low and high prevalence respectively. A total of 180 samples were collected and tested for other blood transmitted infections including WNV using ELISA. A data collection tool was used and analysis was done using SPSS software version 21. This study evaluated donors attended to in facilities within the lake basin versus the capital city which is highly cosmopolitan and devoid of malaria. It was therefore anticipated that some donors are likely to be harboring WNV especially in Nairobi due to its cosmopolitan nature. Majority of the donors were below 35 years of age and were predominantly male. Blood samples that were TTI positive were 40% of which 81.9% were HIV positive. WNV IgG prevalence was 15% in blood donors (95% CI 10-20.5%). Prevalence of cross infection of TTI and WNV was 8.3% (95% CI 4.4-1 2.2%). The prevalence of WVN IgG was highest in the 19-35 years age group (16.5%) and females (21.6%) though the results were not statistically significant. There was no difference in the IgG positivity between the different centers. In conclusion, infection with WNV should be of public health concern because about a fifth of those infected with WNV develop illness.