# A review of the mosquito-borne flaviviruses: Dengue virus and West Nile virus in Southern Africa

## TL;DR

This paper reviews the spread, symptoms, and prevention of dengue and West Nile viruses in Southern Africa, highlighting gaps in surveillance and diagnostic capabilities.

## Contribution

The paper provides a comprehensive review of dengue and West Nile viruses in Southern Africa, emphasizing their public health impact and diagnostic challenges.

## Key findings

- Dengue and West Nile viruses are transmitted by Aedes and Culex mosquitoes, respectively, and are widespread in Southern Africa.
- Sporadic outbreaks of both viruses indicate ongoing public health threats despite limited surveillance and diagnostic capacity.
- Clinical symptoms range from asymptomatic to severe, with no specific antiviral treatments available for either virus.

## Abstract

Dengue virus (DENV) and West Nile (WNV) viruses are important re-emerging mosquito-borne members of the genus Flavivirus that are under-recognized in many parts of Africa. This review aims to evaluate the existing literature on the transmission, epidemiology, diagnostic techniques, clinical presentation and prevention of infection with DENV and WNV in Southern Africa. Literature shows that both DENV and WNV are transmitted by mosquitoes of Aedes spp. and Culex species., respectively, and both viruses are widespread in the Southern African region. Epidemiologically, sporadic outbreaks have been reported of both DENV and WNV in various Southern African countries, indicating the ongoing threat of these viruses. However, the lack of comprehensive surveillance and diagnostic capacity challenges accurate estimation of their true prevalence. Diagnostic techniques for DENV and WNV involve serological tests, molecular tests and viral isolation, enabling prompt diagnosis and differentiation from other febrile illnesses. In Southern Africa, infection with DENV and WNV presents significant public health concerns, with the clinical presentation of both infections ranging from asymptomatic cases to severe manifestations. Symptoms of infection include high fever, myalgia, rash, and, in severe cases, haemorrhagic fever for DENV and neurological complications for WNV. No specific antiviral treatment exists for either virus, underscoring the importance of supportive care and symptom management. To prevent the spread of DENV and WNV in Southern African countries, a combination of prevention and treatment strategies should be employed, including effective mosquito control, continuous monitoring of vector population dynamics, public health education, and surveillance and reporting systems for averting future outbreaks.