By Matt Reese
The soggy winter is at least partially to blame for the Porcine Reproductive and Respiratory Syndrome (PRRS) virus problems that have been plaguing hog producers in eastern Indiana and western Ohio in recent months.
“PRRS is programmed to very rapidly mutate. That is one of the problems in trying to develop a good vaccine that can work against the virus,” said Dr. Bill Minton, of Minton Veterinary Service in Mercer County. “When that virus infects mature animals it can cause reproductive problems including failure to breed, or pregnancy losses. It can ultimately become serious enough that it causes death. In growing pigs it is primarily a respiratory disease. We’ll see mild signs of pneumonia to severe pneumonia followed by sudden death.”
Along with being a problem itself, PRRS can also worsen symptoms of other pathogens.
“A lot depends on whatever secondary pathogens are also present. If you have PRRS, and if you also have the influenza or bacterial infections, these can all compounded by the PRRS virus,” Minton said. “It attacks the immune system.”
PRRS has the potential to cause significant losses.
“In the sow herd, this can be the most significant production losses,” he said. “On the grow/finish side of it, though, it can be somewhat of a challenge in terms of decreased feed efficiency, average daily gain and mortality. The National Pork Board estimates that it affects the industry to the tune of about $660 million a year. That is about $6 that every pig carries with it in added cost due to PRRS. It has a significant economic impact in the industry.”
There has been a recent increase in PRRS in the last two months in western Ohio and eastern Indiana, although it has been fairly active across the Midwest and Upper Midwest most of the winter.
“There is certainly quite a bit of PRRS activity and it has moved its way east as the winter has progressed,” Minton said. “The strains that we are primarily seeing have been very similar to a strain we found two years ago in Western Ohio. Since Christmas, this strain has moved across eastern Indiana and western Ohio very rapidly.”
The weather has played a significant role in the problem. PRRS prefers cool, moist conditions.
“We know this virus can travel 5.5 miles in the right conditions, which are mild to moderate wind, overcast skies and high humidity,” he said. “We have certainly had that in Ohio this winter. It has been a perfect storm.”
PRRS primarily travels in four ways, he said — through the air, on pigs, by people (hands or shoes), and on transportation vehicles (trucks, trailers).
“The most important thing to control this is biosecurity,” Minton said. “Limit the external biosecurity risk of people and transportation. Hold meetings off site and, when people are there, use proper biosecurity measures.”
Minton recommends an imaginary clean/dirty line in the barn separating all outside of barn clothing and footwear from the clothing worn inside the barn. Hand washing is also important. With regard to transportation, trucks and trailers should be disinfected and dried before loading.
“Keep pigs moving one way when they are being loaded to minimize any cross contamination,” he said.
Minton is working with producers in the affected area to develop strategies for addressing the problem and slowing the spread of PRRS. These efforts include group meetings and an online communications tool for affected hog producers that can keep them up-to-date with any new PRRS problems, provide a forum for questions and provide real time communication.