Encephalitic Arboviruses of Africa: Emergence, Clinical Presentation and Neuropathogenesis.

Robyn S. Klein

doi:10.3389/fimmu.2021.769942

Abstract

Many mosquito-borne viruses (arboviruses) are endemic in Africa, contributing to systemic and neurological infections in various geographical locations on the continent. While most arboviral infections do not lead to neuroinvasive diseases of the central nervous system, neurologic diseases caused by arboviruses include flaccid paralysis, meningitis, encephalitis, myelitis, encephalomyelitis, neuritis, and post-infectious autoimmune or memory disorders. Here we review endemic members of the Flaviviridae and Togaviridae families that cause neurologic infections, their neuropathogenesis and host neuroimmunological responses in Africa. We also discuss the potential for neuroimmune responses to aide in the development of new diagnostics and therapeutics, and current knowledge gaps to be addressed by arbovirus research.

Highlights

Recent studies indicate that climate changes in Africa may lead to a shift in vector-borne diseases from malaria to arboviruses due to differential effects of warming temperatures on the mosquito species that transmit these pathogens to humans [summarized in [1]]
Neurotropic arboviruses that are transmitted by Aedes aegypti, and cycle between wildlife and livestock or humans in west sub-Saharan Africa, are likely to emerge in other areas of Africa where the current climates supports Anopheles gambiae transmission of malaria [2, 3]
While the majority of infections with neurotropic arboviruses are asymptomatic, many persons develop flu-like symptoms that progress to neuroinvasive diseases in approximately half of symptomatic patients

Summary

INTRODUCTION

Recent studies indicate that climate changes in Africa may lead to a shift in vector-borne diseases from malaria to arboviruses due to differential effects of warming temperatures on the mosquito species that transmit these pathogens to humans [summarized in [1]]. Neurotropic arboviruses that are transmitted by Aedes aegypti, and cycle between wildlife and livestock or humans in west sub-Saharan Africa, are likely to emerge in other areas of Africa where the current climates supports Anopheles gambiae transmission of malaria [2, 3]. While the majority of infections with neurotropic arboviruses are asymptomatic, many persons develop flu-like symptoms that progress to neuroinvasive diseases in approximately half of symptomatic patients. We will provide current knowledge gaps and perspectives regarding future research in neurotropic arboviruses

Flaviriruses and Alphaviruses in Africa

ZIKV DENV

Rare encephalitis

Findings

KNOWLEDGE GAPS FOR FUTURE RESEARCH