Flaviviruses of public health concern in South Africa: Present and future threats

Background: The resurgence and widespread transmission of flaviviruses over the past few decades are particularly concerning. Aim: This review discusses the structure, aetiology, transmission, detection, diagnosis and prevention strategies for flaviviruses in South Africa. Setting: Climate change, urbanisation, travel, population growth and changes in viral genetics are all driving the establishment and reemergence of flaviviruses in previously non-endemic areas. Medically important flaviviruses such as dengue, Zika, West Nile and yellow fever have geographically expanded, affecting millions worldwide. Method: The study was conducted using the search engines, including Google Scholar, PubMed, ScienceDirect and Medline. This review includes published articles on flaviviruses from South Africa and beyond. Results: Climate change, urbanisation, population growth and changes in viral genetics contribute to the reemergence of flaviviruses. The West Nile virus (WNV) is the most prevalent flavivirus detected in both animals and humans in South Africa. Lesser-known flaviviruses such as Banzi virus (BANV), Bagaza virus (BAGV), Spondweni virus (SPOV), Wesselsbron virus (WSLV) and Usutu virus (USUV) have also been identified in the region, but their current status remains unclear, possibly due to limited surveillance programmes and/or misdiagnosis. Nucleic acid amplification tests, followed by sequencing and serological assays, are commonly employed technologies for surveillance in South Africa. While there are no licensed vaccines for human use against these flaviviruses, licensed vaccines for WSLV and WNV are available for animals. Conclusion: There is a need to develop molecular diagnostic tools for local strains to prevent misdiagnosis, enhance surveillance programmes, implement preventive measures and facilitate the development of therapeutic agents and vaccines. Contribution: This review provides insight into the significant health risks that flaviviruses pose to humans and animals. Additionally, it highlights the limitations of diagnostic methods and preventative measures, thereby enhancing the management of these infections.