Enzootic bovine leucosis

ENZOOTIC BOVINE LEUCOSIS

A national program has been very successful in eradicating the EBL virus from the Australian dairy herd.This virus is also known as Bovine Leukemia Virus (BLV).

What to look for

  • EBL can take many forms depending on what body systems are affected
  • Only about 1 in 20 infected animals show any evidence of the disease
  • Affected animals go off their feed and become weak and debilitated
  • Sometimes enlarged lymph nodes can be felt as lumps under the skin

Cause

EBL is caused by a virus which infects white blood cells and persists for the life of the animal.

Animals likely to be affected

Adult beef animals. EBL occasionally occurs in animals as young as two years of age.

Other diseases with similar signs

Cancers and other chronic diseases that cause weakness and weight loss in older animals.

Confirming the diagnosis

Blood/milk test for the presence of specific antibodies.

Spread of the disease

The virus can be transmitted from infected cows to their unborn calves but it is usually spread between animals by tiny amounts of blood that can be exchanged during routine activities like vaccination, castration, ear tagging, dehorning, rectal examination or natural mating.

A national program has been very successful in eradicating the disease from the Australian dairy herd.  Confirmed freedom was declared in 2012.

Some beef herds in Australia may still have a low level of EBL and it is important that farmers thinking of introducing beef bulls or other beef animals check to ensure that they are coming from properties free of the disease.

Risks to people

Any virus in raw milk is destroyed by pasteurisation.

Risk factors

  • Introducing beef animals of unknown EBL status
  • Not isolating introduced animals until tested clear
  • Using unsterilised implements on the dairy herd that have previously been used for procedures on beef cattle such as ear tagging, castration or disbudding

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