Incidence, drivers and global health implications of the 2019/2020 yellow fever sporadic outbreaks in Sub-Saharan Africa

• Published in: Pathogens and disease Vol. 79; no. 4
• Main Authors: Uchenna Emeribe, Anthony, Nasir Abdullahi, Idris, O. R. Ajagbe, Odunayo, Egede Ugwu, Charles, Oloche Onoja, Solomon, Dahiru Abubakar, Sharafudeen, Modesta Umeozuru, Chikodi, Sunday Animasaun, Olawale, Omoruyi Omosigho, Pius, Mukhtar Danmusa, Umar, Alhaji Baba Mallam, Mala, Saidu Aminu, Maijiddah, Yahaya, Hadiza, Oyewusi, Silifat
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01-06-2021
• Subjects: Aedes - virology; Africa South of the Sahara - epidemiology; Animals; Climate Change; Disease Outbreaks; Environmental factors; Environmental impact; Fever; Global health; Global Health - trends; Humans; Immunization; Incidence; Land use; Mosquito Vectors - virology; Outbreaks; Public health; Rain; Vaccination; Vaccination - methods; Vaccines; Vector-borne diseases; Yellow fever; Yellow Fever - epidemiology; Yellow Fever - prevention & control; Yellow Fever - transmission; Yellow Fever - virology; Yellow Fever Vaccine - administration & dosage; Yellow fever virus - pathogenicity; Yellow fever virus - physiology; Africa South of the Sahara; Sub-Saharan Africa; climatic change; yellow fever outbreak; travel health; Sub-Saharan Africa; yellow fever vaccination
• ISSN: 2049-632X; 2049-632X
• DOI: 10.1093/femspd/ftab017

ABSTRACT
The 2019 and 2020 sporadic outbreaks of yellow fever (YF) in Sub-Saharan African countries had raised a lot of global health concerns. This article aims to narratively review the vector biology, YF vaccination program, environmental factors and climatic changes, and to understand how they could facilitate the reemergence of YF. This study comprehensively reviewed articles that focused on the interplay and complexity of YF virus (YFV) vector diversity/competence, YF vaccine immunodynamics and climatic change impacts on YFV transmission as they influence the 2019/2020 sporadic outbreaks in Sub-Saharan Africa (SSA). Based on available reports, vectorial migration, climatic changes and YF immunization level could be reasons for the re-mergence of YF at the community and national levels. Essentially, the drivers of YFV infection due to spillover are moderately constant. However, changes in land use and landscape have been shown to influence sylvan-to-urban spillover. Furthermore, increased precipitation and warmer temperatures due to climate change are likely to broaden the range of mosquitoes' habitat. The 2019/2020 YF outbreaks in SSA is basically a result of inadequate vaccination campaigns, YF surveillance and vector control. Consequently, and most importantly, adequate immunization coverage must be implemented and properly achieved under the responsibility of the public health stakeholders.
The 2019 and 2020 yellow fever (YF) virus infection reemergence in some Sub-Saharan African countries reflects the interplay and complexity of Aedes mosquitoes' competence, inadequate YF vaccine coverage, environmental factors and climatic changes.