June 9, 2008

 

US study proves vaccines effective against PRRS

 
 

A 3-year study by a researcher from Nebraska have proven that porcine reproductive and respiratory syndrome (PRRS) vaccines can be effective on nursery pigs.

 

John Waddell, veterinarian in Sutton, Nebraska conducted the study on PRRS vaccines in association with researchers at pharmaceutical firm Boehringer Ingelheim Vetmedica.

 

PRRS is a virulent viral disease with numerous strains and has caused extensive losses in the nursery and grow-finish stages of production. Research studies also show that 88 percent of the costs associated with PRRS are incurred in growing pigs.

 

Because the PRRS virus has many strains, some producers have questioned the ability of vaccines to effectively control the disease in commercial operations, according to Waddell.

 

The results of the study, which showed a significant reduction in death losses and improved overall performance, were presented Thursday at the World Pork Expo.

 

The study was conducted at a large commercial swine operation and involved more than 600,000 pigs. Weaned pigs from herds that tested positive for PRRS were vaccinated with a modified-live virus at approximately three weeks of age. Mortality rates and growth performance were compared with those from non-vaccinated pigs from PRRS-negative units.

 

The average mortality rate at the three-site grow-finish operation prior to the test was 9 percent. The mortality rate in the more than 331,000 pigs which were vaccinated through the test period was 2.65 percent. This was about equal with the non-vaccinated pigs from PRRS-negative systems.

 

Other sets of pigs from both PRRS-positive and PRRS-negative sow herds were tested in 2006, using more than 500,000 pigs.

 

Estimates of the benefits to the cost of the vaccines for producers may vary from four to one to as high as 10 to one, depending on various factors, the presenters said.

 

PRRS can also be a co-factor in other swine diseases such as porcine circovirus-associated disease. In such cases, the presence of both viruses can result in more severe outbreaks and increased losses.

 

Control of PRRS requires a systematic approach, including the use of vaccines, appropriate biosecurity, management and sanitation measures, said Reid Phillips, technical manager with Boehringer Ingelheim Vetmedica.