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. Life long carriers of the virus, including cases of mucosal disease, are a consequence of infection in early foetal life (usually before 100 days gestation). These life long 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

Test

Sample(s) required

Days of the week test is conducted

Turnaround time1

Pestivirus antibody AGID

Clotted blood (red top tube) or foetal fluid

Tuesday & Friday

3-5 days

Pestivirus antibody ELISA

Bulk milk

Batch tested weekly

Up to 7 days

Pestivirus antigen capture ELISA (PACE)

Clotted blood (red top tube), lithium heparin blood (green top tube), EDTA blood (purple top tube), skin or fresh tissue

Batch tested 2-3 times weekly

5-7 days

PI-test®

Hair

Batch tested 2-3 times weekly

5-7 days

Pestivirus PCR

Clotted blood (red top tube), EDTA blood (purple top tube), bulk milk, swab in PBGS or fresh tissue

According to demand

2-3 working days

Pestivirus VI

Clotted blood (red top tube), swab in PBGS or semen

According to demand

3-4 weeks

Pestivirus VNT

Clotted blood (red top tube)

Batch tested on Friday

1-2 weeks

1 Turnaround times are provided as a guide only. For specific information about your submission please contact Customer Service.

Specimen requirements

Detection of virus in live animals

Blood (with anti-coagulant)

  • 10 ml of blood collected into a lithium heparin treated tube
    • Submitted chilled
  • 10 ml of blood collected into an EDTA tube
    • Submitted chilled

Blood (without anti-coagulant)

  • For animals over 3 months of age collect 10 ml of blood into a plain red top tube
    • Do not use serum separator tubes.
    • Submit chilled

Hair

  • Hair samples may be used to detect the virus using the PI-test®.
  • Collection kits can be ordered free of charge
  • The kits contain detailed notes on hair collection.

Milk

  • Bulk milk
    • Submit chilled

Semen

  • Semen straws or raw semen

Skin

  • Ear notch samples (skin) can be used for animals of any age.
    • Submit chilled

Swab

  • Nasal swab collected from affected animal
    • Send in viral transport media (PBGS)
  • Used in cases of respiratory disease, where one is trying to detect acute infections rather than PI animals.

Detection of virus in dead animals and foetuses

Fresh tissues

  • Spleen, lung or lymph node
    • Submit chilled

Skin

  • Ear notch (skin) can be used for animals of any age
    • Submit chilled

Detection of antibodies in live animals

Blood (without anti-coagulant)

  • 10 ml of blood collected in a plain red top tube
    • Submit chilled
  • Serum samples from 10-15 cows may provide evidence of the extent of herd infection. This information may help with management decisions regarding pestivirus. In cases of embryonic mortality or abortion this information may allow more selective investigation to confirm pestivirus involvement.

Milk

  • Bulk milk samples
    • Submit chilled

Detection of antibodies in foetuses

Foetal fluid

  • Pericardial, pleural or peritoneal (in order of preference).
    • Submit chilled
  • For IgG test initially and for pestivirus antibody if the IgG level is elevated.
  • Please note on the submission form I if colostrum was given to a neonate
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.