Bovine Ephemeral Fever (Three-Day Sickness) in Cattle

Quick answer: Bovine ephemeral fever (BEF), or "three-day sickness," is a viral, insect-borne fever of cattle and buffalo that flares up in the Indian monsoon and post-monsoon when mosquitoes and midges peak. It is rarely fatal and most animals recover in about three days, but it causes a sharp fever, stiffness and a sudden milk drop, and downer or heavily pregnant animals need close nursing. There is no specific cure: care is supportive (rest, vet-prescribed anti-inflammatories, fluids, shade and easy feed), and prevention rests on vaccination where available plus vector control.

What is bovine ephemeral fever?

BEF is caused by the bovine ephemeral fever virus, an arbovirus (a rhabdovirus) spread by biting insects such as mosquitoes and Culicoides midges, not by direct animal-to-animal contact. Because it depends on insect vectors, outbreaks track the warm, wet weather of the monsoon and the weeks after, exactly when stagnant water lets vectors breed. High-yielding cows and heavy bulls usually show the most severe signs; morbidity in an outbreak can be high even though mortality stays low.

Signs to watch for

• Sudden high fever (often 40-41°C), shivering and dullness
• Stiffness and a shifting-leg lameness; the animal is reluctant to move
• Sharp drop in milk yield, sometimes to near zero for a few days
• Watery discharge from the eyes and nose, drooling and reduced rumination
• Muscle tremors; some animals go down and cannot rise ("downers")

The classic pattern is a fever that peaks and passes within about three days, hence the name. Most animals recover quickly, but complications can include aspiration pneumonia in downers, temporary infertility in bulls and occasional abortion in late-pregnancy cows. Milk yield may not fully return until the next lactation.

When it is an emergency

An animal that cannot rise, that bloats while lying down, that struggles to breathe, or a late-pregnancy cow going down needs a veterinarian immediately. Prolonged recumbency is dangerous in itself, so never assume a downer will simply "recover in three days" without care.

Treatment and nursing care

There is no antiviral cure for BEF; recovery is driven by good nursing. Work with your veterinarian, who may prescribe an anti-inflammatory (NSAID) to reduce fever and stiffness and calcium therapy for downers, because affected animals can develop a milk-fever-like weakness. Key nursing steps:

• Provide shade, clean water within easy reach and soft, palatable feed
• Turn recumbent animals from side to side every few hours to prevent muscle damage and bloat
• Keep the animal calm and do not force it to walk
• Rebuild appetite and rumen function once the fever breaks

As the fever passes, animals are often left off-feed with a sluggish rumen. A herbal liver tonic such as Cattle Remedies Heprich can support appetite and metabolic recovery, while a rumen and digestive tonic like Cattle Remedies Ruminova, an improved Cattle Remedies formulation, helps restore rumen function and feed intake. For weak or downer animals, your vet may advise a bioavailable calcium supplement such as Cattle Remedies Calcicril, and where a cough or nasal discharge lingers, Cattle Remedies CufCRIL supports respiratory recovery. These are supportive measures, not a substitute for veterinary treatment. To compare hepatoprotectives, see our guide to the best liver tonic for cattle in India.

Prevention: break the insect cycle

Because BEF is vector-borne, prevention centres on cutting biting-insect numbers and, where available, vaccination:

• Drain or empty stagnant water, blocked drains and containers where mosquitoes breed
• Use approved repellents or sprays and screen the shed, especially at dawn and dusk when vectors are most active
• Ask your veterinarian about BEF vaccination ahead of the vector season
• Keep animals in good body condition and mineral status so they weather the fever better; a balanced chelated mineral mixture such as Cattle Remedies Verymin supports overall resilience

Frequently asked questions

Is three-day sickness contagious between cattle?

No. BEF does not spread by direct contact; it is transmitted by biting insects. That is why control focuses on vectors and stagnant-water management rather than isolation alone, though sick animals should still rest away from the herd.

Will my cow's milk come back after BEF?

Milk usually recovers partly as the animal returns to feed, but in a hard-hit high-yielder the drop can persist for the rest of that lactation. Prompt supportive care and getting the cow back on feed quickly give the best chance of recovery.

Can BEF kill cattle?

Deaths are uncommon and usually linked to complications such as prolonged recumbency or aspiration pneumonia rather than the virus itself. Careful nursing of downers is the single biggest factor in avoiding losses.

This article is for general education and does not replace veterinary advice. Always consult a qualified veterinarian for diagnosis and treatment, and report suspected notifiable disease as required in your state.

References: Bovine Ephemeral Fever in Asia: Recent Status and Research Gaps (NCBI/PMC); ICAR-NDRI Dairy Knowledge Portal: Ephemeral Fever.