EPIDEMIOLOGICAL AND ENTOMOLOGICAL STUDIES ON THE MOSQUITO-BORNE RIFT VALLEY FEVER VIRUS IN SOUTHERN BORDERS OF EGYPT

Abstract

Rift Valley fever (RVF) is an acute zoonotic viral disease transmitted by various mosquito vectors. Aswan governorate is considered as main route of importing Rift Valley Fever virus (RVFV) to Egypt. This study collected and identified mosquito species occurred in diverse districts across this border area. Three genera and five species were identified from the study districts: Culex pipiens, Cx. perexiguus, Cx. antennatus, Ae. (Ochlerotatus) caspius, and An. pharoensis. Here, we identified mosquito diversity and sex ratio based on sampling districts. All mosquito pools tested negative via RVFV-specific polymerase chain reaction. The serum samples were collected from goats, camel, sheep, and cattle to detect anti-RVFV IgG and anti-RVFV IgM. The study showed that 123/381 (32.2%) of the samples were seropositive and carried anti-RVFV IgG. The remaining 258 samples (67.77%) were tested negative. The seropositive rates were different in tested animals and study districts. A total number of 336 serum samples were analyzed using ID Screen Rift Valley Fever IgM Capture to detect the recent RVF infections in sheep, goat, and cattle. All the tested samples were negative based on anti-RVFV IgM. Finally, we mapped the current and future global potential distributions of RVFV and its vectors using the ecological niche modeling (ENM) approaches. These analyses were performed on both present-day and future-day conditions. Future predictions were estimated under two representative concentration pathways (RCPs) of anticipated Co2 emissions. The study detailed map provided characteristic patterns of environmental suitability for RVFV and eleven vectors in Africa and Arabian Peninsula with emphasis to Egypt. The maps also anticipated the areas at risk of RVFV and vector invasion in Africa and the Arabian Peninsula considering future climate conditions that shape the future niche for both transmission cycle components. Interestingly, these maps provide as a baseline data for detailed vector and RVF surveillance, vaccination, and vector control programs. The latter reflected the public health importance of the current study.