Arbovirus Vectors of Epidemiological Concern in East Africa: A systematic review of entomological studies (1940-2020)

Abstract

Background: Emerging and re-emerging arboviral infections are increasing global public health concerns due to their rapid geographical spread and burden. In the East African region, knowledge of the diversity and distribution of their shared vectors remains incomplete. This review summarizes the state of the entomological studies on the mosquito vectors of arboviruses such as Yellow Fever, Rift Valley Fever, Zika, Dengue and Chikungunya fever viruses and the risk factors affecting virus transmission. The rationale of this systematic review was to characterize entomological studies that have been conducted in the East African region and establish the trend of epidemics of various arboviral infections from 1940-2020 to fill the existing knowledge gap. Material and Methods: A systematic search was conducted using PubMed, Science Direct and bioPreprint to identify eligible studies using search terms: Yellow fever, Dengue, Chikungunya, Rift Valley Fever, arboviruses AND vectors in East Africa. Others were: Aedes, Culicine mosquitoes AND Tanzania/ Kenya/ Rwanda/ Uganda/ Burundi/ Sudan. Results: A total of 126 studies met the systematic review criteria. From 1940 to July 2020, a total of 389 arbovirus vector mosquito species have been described including 35% Aedes, 31% Culex, 12% Anopheles, 8% Coquillettidia, 5% Taeniorhynchus, 2% Eretmopodites and 7% other genera. The diversity of arbovirus vectors was highest in Kenya (151 spp) followed by Uganda (102 spp), Sudan (90), Tanzania (38 spp), Rwanda and Burundi recorded with only a few species. Conclusion: Based on this review, we compile a database on arbovirus vector distribution paired with the viruses they transmit in the East African region. The vector species appear to be the same in the region and this calls for developing a strategic regional surveillance system for the prevention and control of future arboviral infections epidemics.