Bovine Ephemeral Fever (BEF)

Bovine ephemeral fever (BEF), also known as a three-day sickness, is a viral infectious disease that is prone to occur in major cattle breeding areas. Although the lethality rate is low and often shows a benign process, it will seriously affect the normal feeding of the herd, resulting in a gradual decline in the resistance of the cattle. This will directly affect the economic benefits of the farm and is unfavorable to the development of the cattle breeding industry. As a CRO specializing in animal disease diagnostics, BioVenic is dedicated to assisting customers in mitigating the negative impacts of BEF. We achieve this commitment through the provision of services encompassing diagnostics development, vaccine development, and drug development.

Etiology

BEF is caused by the bovine ephemeral fever virus (BEFV), a member of the genus Ephemerovirus in the family Rhabdoviridae. The virus is single-stranded, negative-sense RNA, and its virion is enveloped, bullet-shaped, and slightly tapered toward the rounded end. The dimensions of BEFV virion range from 60 to 80 nm in width and 120 to 170 nm in length.

BEFV is considered to exist as a single serotype worldwide, but antigenic variation has been observed through cross-neutralization tests, monoclonal antibody panels, and epitope mapping. At least four antigenic subtypes of BEFV have been identified, although there is only one serotype.

BEFV's antigenic variation emphasizes the importance of considering regional viral strains for vaccine development and disease management.

Fig. 1 Structural diagram of BEFV.¹

Distribution

BEF is widespread in several regions globally, with a particular emphasis on its prevalence in areas with suitable insect vectors, especially mosquitoes. Countries in Asia, Australia, and Africa have reported significant outbreaks, leading to substantial economic losses in affected cattle populations.

Sustainable Animals

Cattle and buffalo are the primary hosts and are highly susceptible to BEF. However, other ruminants, such as sheep, and goats, can also contract the disease, albeit with varying degrees of susceptibility.

Transmission

Blood-sucking insects such as mosquitoes, midges, and flies are important vectors of BEFV. These blood-sucking insects bit the sick cows and then bit the healthy cows again to cause the spread of BEFV.

The epidemic of BEF is cyclical, once every 6-8 years or 3-5 years, and a small-scale epidemic often occurs after a major epidemic.

BEF has obvious seasonality and is generally popular in late summer to early autumn when mosquitoes breed.

Fig. 2 Transmission cycle of BEFV.¹

Pathogenesis

Upon entry into the host, the Bovine ephemeral fever virus targets various tissues, including lymph nodes, respiratory tract, and muscle cells. The virus replicates within these cells, leading to viremia and the subsequent manifestation of clinical signs.

Signs and Symptoms

After being infected with BEFV, the symptoms of sick cattle generally lasted for 3-5 days, and most of the sick cattle recovered well after treatment. Affected cattle exhibit a range of clinical signs, usually including,

Diagnosis

The diagnosis of BEFV can start with pathogen detection or antigen and antibody detection.

• Pathogenic Detection
  
  • Isolation and identification of BEFV: The blood of sick cows in the febrile stage can be collected to inoculate suckling mice and suckling hamsters or to carry out cell culture, and then isolate and identify BEFV.
  • RT-PCR: The virus was identified by amplifying the BEFV G gene fragment.
• Serological Detection
  
  • Virus Neutralization Assay
  • Agar gel immunodiffusion assay
  • ELISA
  • Complement fixation assay, etc.

To help achieve early diagnosis of BEFV, we provide customers with the above-mentioned immunodiagnostics and molecular diagnostics development services.

Treatment

Currently, no specific antiviral treatment exists for BEF. Management primarily focuses on providing supportive care to affected cattle. This includes rest, anti-inflammatory medications, and ensuring adequate nutrition and hydration to aid in the recovery process.

Prevention and Control

• When sick cattle are found in the herd, they should be isolated, diagnosed, and reported immediately.
• Rational use of drugs, and intensive care, improve the disease resistance of sick cattle and reduce clinical symptoms.
• BEFV quarantine work should be done before and after cattle introduction.
• The imported cattle should also be fed in isolation before entering the field to avoid the cross-regional spread of BEF caused by the introduction of sick cattle.
• Clean up the manure and other breeding waste around the cowshed in time.
• Use conventional disinfectants for disinfection, and the frequency of disinfection should be increased after BEF cases appear.
• In the season of mosquito breeding, it is necessary to disinfect mosquitoes, midges, flies, and other blood-sucking insects to cut off the transmission route of BEFV.
• Do a good job in the care of pregnant cows or other cattle at special development stages, enhance the disease resistance of the herd, and reduce the stress of the herd.
• For BEF endemic areas, cattle herds should be vaccinated well, and BEFV inactivated vaccine can be used to vaccinate cattle over 6 months old. Also, give a booster shot 8-10 weeks before mosquito season.

BioVenic is at the forefront of developing innovative solutions for animal diseases. Our scientists help customers develop vaccines, and diagnostics solutions, and explore new treatment options for BEF. If you would like more information, please feel free to contact us.

Reference

1. Pyasi, Shruti, et al. "Immunoinformatics approach to design multi-epitope-subunit vaccine against bovine ephemeral fever disease." Vaccines 9.8 (2021): 925.