Prevention and control

Control of this disease is difficult, therefore prevention is key, and eradication is necessary in flocks where the virus is endemic. It may take several years to completely eliminate the virus from a flock and there are several eradication strategies that can be followed:

These methods are very labor intensive and expensive and there is considerable risk of re-infection of the flock following eardication. 

To confirm eradication of OPPV, flocks should be tested bi-annually until two consecutive negative herd tests are obtained.

Once the flock is considered to be free of OPPV, all animals entering the flock should be tested. It is important to be aware when sero-testing ewes that immunoglobulin titres for OPPV may be low just before and after parturition because the ewes may be sequestering anti-viral antibodies in their colostrum.

Unfortunately, a vaccine for OPPV is not yet available. The virus’ mutagenic properties make it difficult for vaccine development and strategy.