Rift Valley fever – a growing threat to humans and animals

Abstract

Rift Valley fever (RVF) is a zoonotic, vector-borne infectious disease of ruminants and camels transmitted mainly by the Aedes and Culex mosquito species. Contact with the blood or organs of infected animals may infect humans. Its etiological factor is the Rift Valley fever virus (RVFV) of the Phlebovirus genus and Bunyaviridae family. Sheep and goats are most susceptible to infection and newborns and young individuals endure the most severe disease course. High abortion rates and infant mortality are typical for RVF; its clinical signs are high fever, lymphadenitis, nasal and ocular secretions and vomiting. Conventional diagnosis is done by the detection of specific IgM or IgG antibodies and RVFV nucleic acids and by virus isolation. Inactivated and live-attenuated vaccines obtained from virulent RVFV isolates are available for livestock. RVF is endemic in sub-Saharan Africa and the Arabian Peninsula, but in the last two decades, it was also reported in other African regions. Seropositive animals were detected in Turkey, Tunisia and Libya. The wide distribution of competent vectors in non-endemic areas coupled with global climate change threaten to spread RVF transboundarily. The EFSA considers the movement of infected animals and vectors to be other plausible pathways of RVF introduction into Europe. A very low risk both of introduction of the virus through an infected animal or vector and of establishment of the virus, and a moderate risk of its transmission through these means was estimated for Poland. The risk of these specific modes of disease introduction into Europe is rated as very low, but surveillance and response capabilities and cooperation with the proximal endemic regions are recommended.

Mosquito-Associated Viruses and Their Related Mosquitoes in West Africa

“…MBVs, such as RVFV, can infect and cause abortion in humans and domestic animals (e.g., ruminants), and cause important economy losses [ 6 , 7 , 22 , 23 ], and others, including YFV, DENV, CHIKV, ZIKV, and WNV, are responsible for millions of disease cases and several thousands of deaths among humans [ 2 ]. However, there remain large gaps in our understanding of the current distribution of these arboviral diseases as vector-borne research and control in the region is focused primarily on Anopheles mosquitoes, Plasmodium , and malaria disease [ 2 , 3 ].…”

NSG-Mice Reveal the Importance of a Functional Innate and Adaptive Immune Response to Overcome RVFV Infection

“…Rift Valley fever (RVF) is a zoonotic disease caused by Rift Valley fever virus (RVFV) that is endemic in many regions of Africa and Arabia [1,2]. It poses a threat to many host species including cattle, goats, sheep and humans [2][3][4].…”

“…While most human cases present as subclinical flu-like symptoms, severe or even fatal complications may occur, and the estimated case-fatality rate varies between 0.5 and 2% [9]. These complications include severe hemorrhagic fever, jaundice or a late-onset retinitis and encephalitis [3,4,9]. In addition to impactful outbreaks in Africa, opportunities of RVF introduction into Europe and North America include accidental emergence via animal trading, the spread of mosquito vectors during the course of global warming or bioterrorist attack scenarios [2,4,10].…”

“…These complications include severe hemorrhagic fever, jaundice or a late-onset retinitis and encephalitis [3,4,9]. In addition to impactful outbreaks in Africa, opportunities of RVF introduction into Europe and North America include accidental emergence via animal trading, the spread of mosquito vectors during the course of global warming or bioterrorist attack scenarios [2,4,10]. Because of these threats, RVFV has been named an "agent of concern" by the United States Department of Agriculture (USDA) and the Center for Disease Control and Prevention (CDC) [4].…”

“…In addition to impactful outbreaks in Africa, opportunities of RVF introduction into Europe and North America include accidental emergence via animal trading, the spread of mosquito vectors during the course of global warming or bioterrorist attack scenarios [2,4,10]. Because of these threats, RVFV has been named an "agent of concern" by the United States Department of Agriculture (USDA) and the Center for Disease Control and Prevention (CDC) [4]. It is under surveillance by the International Organization for Animal Health (OIE) as well as being a subject of ongoing scientific interest [11][12][13].…”