A Systematic Review of Yellow Fever Outbreaks and Public Health Responses in Nigeria.

Background: Yellow fever (YF) outbreaks continue to occur in Nigeria with a high mortality rate despite a well-established mode of transmission and the availability of a potent vaccine. This review is aimed at describing the epidemiology, determinants, and public health responses of yellow fever outbreaks in Nigeria from 1864 to 2020. Methodology: The guidelines for the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) were used to conduct the review from November 2020 to April 2021. PubMed database, WHO library databases, and Google Scholar were used to search for relevant published materials including original and reviewed articles, conference papers and case reports from 1864 to 2020. Results: Forty - eight articles and reports were included in the final reviews. Twenty - three outbreaks were described involving 33,830 suspected, presumptive, or confirmed cases of yellow fever and 8,355 deaths. The outbreaks occurred in every state of Nigeria including the Federal Capital Territory mostly during the rainy season. Low immunity in the population or low vaccination coverage, poor vector control, rainforest or savanna vegetation, rural-urban migration, and imported virus by travelers were common determinants noted. Public health responses have been through, centrally coordinated laboratory support, case management, emergency immunization, vector control, and surveillance. Conclusion: Yellow fever outbreaks have increased in frequency and geographical spread with associated mortality rates. To stem the tide, mass immunization with 17D vaccines is encouraged, planned urbanization with adequate vector control measures enforced, effective case definition, vector surveillance, and effective awareness campaigns should be emphasized.