Inter – Epidemic Transmission Of Rift Valley Fever Virus In Ngorongoro District, Northern Tanzania

EXTENDED ABSTRACT

Rift Valley fever virus (RVFV) causes an acute Rift Valley fever (RVF) disease in humans and domestic ruminants whose occurrence assumes an epidemic pattern in most cases. Understanding the maintenance of RVFV in susceptible hosts and potential vectors during inter-epidemic periods (IEP) is vital for better understanding of disease transmission dynamics. The aim of this study was to investigate the transmission dynamics of RVFV in Ngorongoro district, Northern Tanzania. This study involved Rift Valley fever virus-Immunoglobulin G (RVFV-IgG) seropositive samples (n=160) from cattle, sheep, goats and humans that were collected from previous cross-sectional survey conducted in parallel with mosquito sampling in Malambo, Meshili, Osinoni, Endulen and Nainokanoka villages. The selected seropositive samples were tested for the presence of RVFV using the real- time Reverse Transcription polymerase chain reaction (qRT-PCR) and conventional RT-PCR. Adult mosquitoes were collected outdoor using the Centres for Disease Control and Prevention (CDC) light traps baited with carbon dioxide. The traps were set in proximity to potential breeding sites and cattle kraals. The mosquitoes were identified using conventional morphological keys, in addition, Anopheles gambiae complex species were identified using Conventional PCR. Viral RNA was extracted directly from serum samples and mosquitoes using a QIAamp Viral RNA Mini Kit (QIAGEN), the molecular detection of RVFV from serum samples was first performed using qRT- PCR, positive samples were then rescreened using conventional RT-PCR. A total of 96 Pools each containing 10 monospecific potential mosquito vectors were also tested for RVFV RNA using qRT-PCR.