Pork producers who manage to produce pigs that test negative to the porcine reproductive and respiratory syndrome virus should be able to enjoy the fruits of their labor in the form of improved pig performance and better financial returns.

But increasingly, the ability to carry out that goal is being cut short in the hog-dense regions of the Corn Belt, says Tim Loula, DVM, Swine Vet Center, St. Peter, Minn.

PRRS was first diagnosed in the United States in 1987. Despite many and varied efforts to control the virus, it seems to grow worse every year, Loula expressed his lament in a talk at the American Association of Swine Veterinarians annual meeting in March in Phoenix, Ariz.

PRRS strains continue to grow in number, severity and transmissibility; the virus has evolved into an “aerosol transmission pathogen,” he says.

PRRS outbreaks are often complicated by swine influenza virus, Mycoplasma pneumonia and sometimes porcine circovirus type 2. The result is that the grow-finish disease complex has become much more challenging to manage, Loula observes.