Background: Rift Valley fever (RVF) is a mosquito-borne viral zoonotic disease. Rift Valley fever virus
(RVFV) has been isolated from more than 40 species of mosquitoes from eight genera. This study was
conducted to determine the abundance of potential mosquito vectors and their RVFV infection status in
Ngorongoro District of northern Tanzania.
Methods: Adult mosquitoes were collected outdoors using the CDC light traps baited with carbon dioxide
in five randomly selected villages namely, Meshili, Malambo, Osinoni, Endulen and Nainokanoka. The study
was carried out towards the end of rainy season in May 2013. The traps were set in proximity to potential
breeding sites and cattle kraals. The collected mosquitoes were identified to genus and species using
morphological keys. They were tested for RVFV RNA using real time reverse transcription-polymerase
chain reaction (rRT-PCR).
Results: A total of 2,094 adult mosquitoes belonging to three genera and nine species were collected. Most
of them (87.5%) were collected in Meshili, followed by Malambo (8.2%) and Osinoni (4%) villages. No single
mosquito was collected in Nainokanoka or Endulen. The nine species collected were
Culex pipiens
complex,
Cx. antennatus
,
Cx. tigripes
,
Cx. annulioris
,
Cx. cinereus
,
Anopheles arabiensis
,
An. squamosus
,
An. pharoensis
and
Mansonia uniformis. No RVFV RNA was detected in the mosquito specimens.
Conclusion: Various RVFV potential mosquito species were collected from the study villages. These
mosquito vectors were heterogeneously distributed in the district suggesting a variation in RVF
transmission risk in the study area.