Pestivirus infection (cattle)

Also known as Mucosal disease or Bovine viral diarrhoea virus (BVDV)

Description

Pestivirus is a viral infection of cattle present in feedlots and beef and dairy herds in Australia. Lifelong carriers of the virus, including cases of mucosal disease, are a consequence of infection in early foetal life (usually before 100 days gestation). These lifelong carriers are often termed PI (persistently infected).

Foetal infection which persists into and through post-natal life will have resulted from one of two circumstances:

• Infection of a susceptible dam, probably through contact with a virus carrier, in early (usually 30 to 100 days) pregnancy. Immune tolerance to the virus is induced; or,
• The dam herself is a persistently viraemic and immunotolerant animal.

Pestivirus infection is associated with:

• Embryonic or foetal death
• Reduced fertility
• Congenital malformations
• Perinatal mortality
• Poor growth rates
• Respiratory disease
• Non-specific immunosuppression
• Disease with mortality in calfhood or early adult life

Control

• Vaccination of all breeding cattle
• Removal of carrier animals and maintain strict bio-security (including testing of all animals entering the property)
• Livestock management to ensure all breeding heifers have been infected with pestivirus well before mating

Diagnosis and tests available

Diagnosis

Diagnosis is based on recognition of a syndrome consistent with pestivirus infection in combination with confirmatory laboratory testing.

Tests available

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Note

• Care should be exercised when interpreting serological results from calves less than six months of age because the detection of antibodies may be the result of colostral transfer rather than previous infection.
• Where pestivirus infection and/or mucosal disease has been confirmed, further testing of maternal relatives and enquiry into the history and management of the herd may indicate how or when infection occurred, and what steps can be taken to eliminate the problem.
  
  A newborn calf with congenital deformities, the product of infection at 120-180 days gestation, may be seropositive. Some stillborn apparently normal calves can also be seropositive.
  PI animals are usually antibody negative at birth, but will acquire specific antibody from their dam with colostrum. This colostral antibody may persist up to 6 months. Demonstration of an antibody titre in a live animal usually indicates the animal is not persistently infected, assuming it is old enough to have lost maternal antibody (> 6 months). However, around 5% of PI animals may have antibody to pestivirus.

Specimen requirements

Additional Information