Dengue Vector Distribution and their Infection Status in Selected Regions in Tanzania

Abstract

Dengue fever is an important arboviral infection globally. Tanzania has experienced multiple dengue outbreaks since 2010 leading to mortalities and public distress. Dengue is caused by viruses which are transmitted to humans by vector mosquitoes. Nevertheless, the abundance, distribution and extent of viral infections of these vectors are poorly understood. The aim of this study was to characterize dengue vectors and determine their virus infection rates. Adult mosquitoes were collected from selected regions in Tanzania including Dar es Salaam, Tanga, Coast, and Arusha regions using CO2 baited mosquito magnet traps between December 2018 to February 2019, additional samples were collected during dengue epidemic in June 2019. Samples were fixed in RNA later and preserved at –20 °C for virus detection using Reverse Transcriptase – Polymerase Chain Reaction (RT-PCR). A total of 1530 mosquitoes were collected and morphologically identified as: Aedes (75%), Culex (13%), Anopheles (10%) genera and 2% other mosquitoes. All Aedes mosquitoes were identified as Aedes aegypti of which 46% were from Dar es Salaam, 31% Tanga, 21% Coast and 2% from Arusha. The abundance of A. aegypti significantly differed across sampling locations (p = 4.6425E–09), and the virus infection rate was 2%. The presence of these vectors and the detection of dengue viruses is an indication of ongoing arboviral activities necessitating intensification of vector control programmes.

Keywords: Aedes aegypti; dengue vectors; arboviruses; Tanzania