Three Day Sickness (Bovine Ephemeral Fever) in Cattle

Three Day Sickness, also know as Bovine Ephemeral Fever (BEF), is a mosquito-borne disease affecting cattle across Queensland. It is most commonly seen in warm, wet conditions when mosquito numbers increase.

Although many animals recover within a few days, the disease can cause severe illness, significant production losses, and occasionally death - particularly in large, heavy cattle and bulls. 

At Vet Cross, we regularly see cases during seasonal outbreaks and can provide prompt treatment and vaccination advice for your herd.

What Causes Three Day Sickness?

Three Day Sickness is caused by a virus that is spread by biting insects primarily mosquitoes. It is not spread directly from cow to cow, but outbreaks can move rapidly through a herd when insect number are high.

Risk increases:

• After rainfall
• In warm, humid weather
• In areas with standing water
• During seasonal mosquito surges

Signs of Three Day Sickness

The disease often appears suddenly.

Common signs include:

• High fever (often over 40°C)
• Sudden drop in milk production
• Stiffness or lameness
• Reluctance to move
• Muscle tremors
• Depression and drooling
• Lying down and unable to rise

In severe cases:

• Large cattle may become permanently down
• Secondary muscle damage can occur
• Pneumonia may develop if cattle remain recumbent

The name 'Three Day Sickness" comes from typical recovery time - many cattle improve within 1-3 days. However, not all cases are mild.

Why It Matters

While many animals recover, Three Day Sickness can cause:

• Significant milk production losses
• Weight loss
• Reduced fertility
• Bull infertility (temporary or permanent in severe cases)
• Death in complicated cases

For dairy and breeding operations, the economic impact can be substantial.

Treatment

There is no specific antiviral cure, but supportive treatment can make a significant difference.

Treatment may include:

• Anti-inflammatory medication
• Pain relief
• Nursing care
• Assistance to stand if required
• Monitoring for complications

Early treatment often reduces the risk of prolonged recumbency and secondary muscle damage.

When to Call the Vet

Contact Vet Cross promptly if:

• Multiple cattle develop sudden fever and stiffness
• Animals go down and cannot rise
• Bulls show sudden lameness or weakness
• Milk production drops suddenly in dairy cows
• You are unsure whether symptoms are Three Day Sickness or another condition

Early intervention can prevent complications and reduce losses.

Prevention & Vaccination

A vaccine is available for Bovine Ephemeral Fever (BEF) and can help reduce the severity of outbreaks.

Vaccination is particularly recommended for:

• Valuable breeding stock
• Dairy herds
• Bulls
• Herds in high-risk mosquito areas

Timing of vaccination is important and should be discussed prior to expected mosquito season.

In addition to vaccination:

• Reduce standing water where possible
• Monitor mosquito activity
• Avoid unnecessary movement of stressed cattle during outbreaks

Three Day Sickness in Queensland

Outbreaks tend to occur seasonally, particularly in coastal and warm inland areas of Queensland. Weather patterns play a major role in disease activity.

If you are hearing reports locally, it is often worth discussing vaccination and preparedness before cases appear in your own herd.

Talk to Vet Cross

If you are seeing signs of Three Day Sickness or would like advice on prevention strategies for your cattle, contact Vet Cross.

We can assist with:

• Diagnosis and treatment 
• Vaccination programs
• Herd health planning
• Seasonal risk management

Talk to any of the Vet Cross vets for advise and information on Three Day Sickness and heard health programs. Give Us A Call