Bovine ephemeral fever is an insect-transmitted, noncontagious viral disease of cattle and water buffalo that is present in Africa, the Middle East, Australia, and Asia. Inapparent infections can develop in Cape buffalo, hartebeests, waterbuck, wildebeests, deer, and possibly goats, sheep, and gazelles. 

The virus is ether-sensitive and readily inactivated at a pH below 5 or above 10. 

BEFV can be transmitted from infected to susceptible cattle by IV inoculation; as little as 0.005 mL of blood collected during the febrile stage is infective. To date, infection by virus obtained from virus culture has never succeeded. 

Although the virus has been recovered from several Culicoides species and from anopheline and culicine mosquito species collected in the field, the identity of the major vectors has not been proved.

Transmission by contact or fomites does not occur.

The virus does not appear to persist for long periods in recovered cattle, although it has been detected in lymphoid tissue one week after cessation of viremia. 

Infection results in long-term immunity. 

The prevalence, geographic range, and severity of the disease vary from year to year, and epidemics occur periodically. During epidemics, onset is rapid; many animals are affected within days or 2–3 weeks. Bovine ephemeral fever is most prevalent in the wet season in the tropics and in summer to early autumn in the subtropics or temperate regions (when conditions favour multiplication of biting insects); it disappears abruptly in winter. 

Virus spread appears to be associated with winds and transportation of animals. 

Morbidity rates may be as high as 80%; overall mortality rate is usually 1%–2%, although it can be higher in lactating cows, bulls in good condition, and fat steers (10%–30%). However, reported overall mortality rates have exceeded 10% in outbreaks in several countries. 

Clinical Findings in Bovine Ephemeral Fever 

Clinical signs of bovine ephemeral fever, which occur suddenly and vary in severity, can include the following:

• biphasic to polyphasic fever (40°–42°C [104°–107.6°F])
• shivering
• inappetence
• tearing
• serous nasal discharge
• drooling
• pulmonary emphysema
• increased heart rate
• tachypnoea or dyspnoea
• atony of forestomach’s
• listlessness
• stiffness and lameness
• sudden decrease in milk yield

Affected cattle may become recumbent for 8 hours to > 1 week; some animals display true paralysis. After recovery, milk production can fail to return to normal levels until the next lactation. 

There are anecdotal reports of abortions. These might be an indirect consequence of the disease because the virus does not appear to cross the placenta or affect the fertility of the cow. 

Bulls, heavy cattle, and high-lactating dairy cows are the most severely affected; however, spontaneous recovery usually occurs within a few days. More insidious losses may result from decreased muscle mass and lowered fertility in bulls. 

Diagnosis of bovine ephemeral fever is based almost entirely on clinical signs in an epidemic. 

Hypocalcaemia may occur 1 day after fever onset. 

Treatment and Control of Bovine Ephemeral Fever

• NSAIDs
• Supportive care for recumbent cows

Complete rest is the most effective treatment for bovine ephemeral fever, and recovering animals should not be stressed or worked because relapse is likely. 

NSAIDs (eg, ketoprofen, 3 mg/kg, IM, every 24 hours for 2–3 days), Oral dosing should be avoided unless the swallowing reflex is functional. 

Clinical signs of hypocalcaemia are treated as for milk fever. 

Antimicrobial treatment to control secondary infection and rehydration with isotonic fluids may be warranted.

Zoonotic Risk of Bovine Ephemeral Fever

There is no evidence that humans can be infected with the bovine ephemeral fever virus.

For more information, or if you have any concerns or need assistance with disease prevention, treatment protocols, or selecting the correct products, don’t hesitate to reach out to our resident livestock vet, Dr. Izak van Rensburg, at:

WhatsApp: 081 031 4694

Email: izakjvr@hotmail.com

Original article by Eyal Klement,