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
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 | Clotted blood (red top tube), bulk milk | Batch tested weekly | Up to 7 days |
Pestivirus antigen capture ELISA (PACE) | Clotted blood (red 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 an EDTA tube
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®.
- Hair samples must be submitted to the laboratory promptly and within 2 weeks of collection
- Collection kits can be ordered free of charge by calling Customer Services on 1800 675 623 or ordering online
- The kits contain detailed notes on hair collection. The collection guide is also available online.
Milk
- Bulk milk
- Submit chilled, ideally in milk preservative.
- If milk preservative is unavailable samples may be frozen prior to submission.
Semen
- Semen straws or raw semen (please contact the laboratory prior to submission. For regulatory testing samples must be shipped at specified temperatures)
Skin
- Ear notch samples (skin) can be used for animals of any age.
- Submit chilled in sterile container or in ear notch media
- When sampling groups of >10 animals, ear notch samples should be submitted in ear notch media (media can be requested online)
Swab
- Nasal swab collected from affected animal
- 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
Skin
- Ear notch (skin) can be used for animals of any age
Detection of antibodies in live animals
Blood (without anti-coagulant)
- 10 ml of blood collected in a plain red top tube
- 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.
- The pestivirus antibody AGID is usually preferred to the ELISA for disease investigations, as the time of infection may be inferred from the results
Milk
Detection of antibodies in foetuses
Foetal fluid
- Pericardial, pleural or peritoneal (in order of preference).
- 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.