Despite the availability of PRRS vaccines, experts say there are several reasons why the virus and the disease continue to plague Vietnam’s pig farms. Disease control remains a significant challenge to pig producers throughout the country.
PRRS is still raging
PRRS, also known as blue ear disease, has become a common disease in Vietnam, causing damage mainly in lactating sows and fattening pigs.
The three prevalent strains in the country are the North American VC-2332, the Chinese JXA1-2007 and SX-2009 strain, and the European Lelystad Virus strain. PRRS causes substantial damage to pig farms with infection rates ranging from 20-30% of the total herd.
“In most cases, PRRS does not cause high mortality directly but causes clinical effects such as reduced productivity, respiratory disorders, which lead to pig deaths, culling, and increased veterinary costs,” Nguyen Van Minh, Director of Vet24h Animal Health Services, told Asian Agribiz.
Do the existing vaccines work?
Among the reasons why PRRS prevails in farms are low injection rates and poor-quality vaccines. Also, pork prices have plunged because of ASF, forcing producers to minimize expenses, including those for disease prevention like PRRS vaccines for piglets and porkers.
“These explain why there are different levels of PRRS outbreaks in pig farms in Vietnam,” said Mr Minh.
To avoid mistakes in administering PRRS vaccines, he suggested the following:
1. Educate farmers about the importance of vaccines and vaccination;
2. Advice them to use only reputable PRRS vaccines that are effective against the circulating PRRS virus strains in the country;
3. Make antibody assessment before and after administering the vaccine to validate the quality of the vaccination; and
4. Avoid using more than one PPRS vaccine without consulting veterinarians.
“In many farms, especially private farms, two types of PRRS vaccine are used for pigs of different ages. In Vietnam, farmers tend to use the North American strain PRRS vaccine for gilts and sows. For piglets, they use the highly virulent PRRS Chinese strain,” said Mr Minh.
“Doing this raises the potential risk of an outbreak from the re-emergence of the virulent vaccine virus or a mutation. It also complicates PRRS epidemiology in the farm as well as raises the risks of PRRS and porcine respiratory disease complex outbreaks, causing persistent damage to the farm,” he added.