Bovine ephemeral fever: From underestimated illness to emerging threat - A review of pathogenesis, economic impact, and future control strategies

Abstract

Bovine ephemeral fever (BEF) is an arthropod-borne viral disease caused by the bovine ephemeral fever virus (BEFV) of the genus Ephemerovirus in the family Rhabdoviridae. BEF affects domestic and wild ruminants, particularly cattle and water buffaloes. BEF outbreaks are seasonal in Africa, Asia, the Middle East, and Australia, aligning with the summer and autumn seasons in temperate zones and during the monsoons in tropical areas. Vectors, like biting midges (Culicoides spp.) and mosquitoes (Anopheles and Culex spp.), facilitate BEFV transmission. The disease presents a spectrum of clinical signs, from mild febrile illness and lameness to severe symptoms. These severe signs, including loss of the swallowing reflex, tachycardia, emphysema, and ruminal atony, can escalate to neurological disorders and paralysis. With morbidity rates as high as 80–100 %, BEF has a significant impact on livestock productivity. While BEF is clinically widespread, comprehensive genomic data is limited. This is due to lack of systematic surveillance and sequencing capability in endemic regions. Additionally, the acute and transient nature of BEFV infection, with short viremia phase of lasting about 2–8 days, makes it difficult to timely obtain high-quality viral RNA for generating full-length genomes for sequencing. Symptomatic treatments involve non-steroidal anti-inflammatory drugs (NSAIDs), analgesics, and corticosteroids, yet no licensed antiviral drugs exist. In this review, we highlight BEFV's epizootiology, economic impact, molecular characterization, immune responses, and control measures, aiming to update the current understanding of BEFV for global prevention and eradication efforts.