Mosquito survey in Mauritania: Detection of Rift Valley fever virus and dengue virus and the determination of feeding patterns

Author summaryIn Mauritania, various mosquito-borne viruses responsible for devastating diseases in livestock and/or humans occur, threatening both human and animal health. One of these viruses is the Rift Valley fever phlebovirus (RVFV), which is widespread throughout the African continent and the Arabian Peninsula. The first outbreak in Mauritania occurred in 1987, and epidemics have recurred since then. However, little is known about the maintenance of RVFV during inter-epidemic periods, in the absence of reported outbreaks, and although there is evidence of an active circulation of the virus during these times, only limited data are available on the abundance of RVFV and its vectors in Mauritania. Therefore, this study aimed to collect and examine mosquitoes in different areas where outbreaks have already occurred. Additionally, blood of collected blood-fed mosquitoes was analyzed to identify feeding patterns and thus wildlife potentially acting as RVFV reservoir hosts. Furthermore, the collected mosquitoes were analyzed for the presence of other neglected viruses in order to participate in an elucidation of the circulation of different viruses within the mosquito population in Mauritania and to be able to better prevent disease outbreaks. In Mauritania, several mosquito-borne viruses have been reported that can cause devastating diseases in animals and humans. However, monitoring data on their occurrence and local distribution are limited. Rift Valley fever virus (RVFV) is an arthropod-borne virus that causes major outbreaks throughout the African continent and the Arabian Peninsula. The first Rift Valley fever (RVF) epidemic in Mauritania occurred in 1987 and since then the country has been affected by recurrent outbreaks of the disease. To gain information on the occurrence of RVFV as well as other mosquito-borne viruses and their vectors in Mauritania, we collected and examined 4,950 mosquitoes, belonging to four genera and 14 species. The mosquitoes were captured during 2018 in the capital Nouakchott and in southern parts of Mauritania. Evidence of RVFV was found in a mosquito pool of female Anopheles pharoensis mosquitoes collected in December on a farm near the Senegal River. At that time, 37.5% of 16 tested Montbeliarde cattle on the farm showed RVFV-specific IgM antibodies. Additionally, we detected IgM antibodies in 10.7% of 28 indigenous cattle that had been sampled on the same farm one month earlier. To obtain information on potential RVFV reservoir hosts, blood meals captured engorged mosquitoes were analyzed. The mosquitoes mainly fed on humans (urban areas) and cattle (rural areas), but also on small ruminants, donkeys, cats, dogs and straw-colored fruit bats. Results of this study demonstrate the circulation of RVFV in Mauritania and thus the need for further research to investigate the distribution of the virus and its vectors. Furthermore, factors that may contribute to its maintenance should be analyzed more closely. In addition, two mosquito pools containing Aedes aegypti and Culex quinquefasciatus mosquitoes showed evidence of dengue virus (DENV) 2 circulation in the city of Rosso. Further studies are therefore needed to also examine DENV circulation in Mauritania.