Detection and characterization of mosquito-borne viruses circulating in mosquitoes of Morogoro Municipality, Tanzania

Abstract

Mosquito-borne viruses primarily infect animals and humans causing significant public and veterinary health threat. Transmitted by hematophagous mosquitoes, dengue virus and Rift Valley fever virus are the most common outbreaks that occurred in parts of Tanzania especially in malaria endemic areas. Several studies reported the presence of the viruses in circulation in animals and humans. Therefore, this study sought to investigate the diversity of mosquito-borne virus vectors and to assess the risk of mosquito-borne viral transmission in Morogoro municipality. Molecular detection of these viruses was carried out on Aedes aegypti using reverse transcription polymerase chain reaction (RT-PCR). A total of 7649 mosquitoes comprising of 7224 adults and 424 larvae belonging to five genera (Aedes, Anopheles, Culex, Eretmapodites, Mansonia) and 14 species were collected. The predominant specie was Culex quinquefasciatus 53.9% (n=3891) and Aedes aegypti 44.2% (n=3192), most of the species 43.7% (n= 3156) were collected in Mbuyuni, 22% (n=1587) from Kiwanja cha Ndege, 19.2% (n=1387) from Mwembesongo and Mazimbu and Kilakala with 7.6% (n=549 and 545) respectively. About 70% of the Aedes spp were collected from used car tyres - the major breeding sites. The mosquitoes’ 18S ribosomal ribonucleic acid (rRNA) and viral RNA were successfully amplified, but no specific viruses were detected. However, for the mosquito pools positive for flavivirus, by sequencing the generated PCR products, it was found that there could be false positives due to non-specific amplification of mosquito ribosomal RNA or amplification of arboviral-like sequences integrated into the Ae. Aegypti genome. Nonetheless, this result provides an insight into the abundance and distribution of potential vectors in these wards. The close proximity of these vectors to humans poses high risk of virus transmission in the municipality and calls for rational vector control measures