Swine veterinarians and producers alike would relish eliminating porcine reproductive and respiratory syndrome virus (PRRSV), but achieving elimination on a routine basis in commercial herds is not yet a reality. The key problem is that, unlike most viruses, PRRSV causes a persistent infection in pigs — which is often difficult to detect.  “In terms of profitability and animal welfare, we would like pigs to clear the virus as quickly as possible,” Marcelo Almeida, postdoc research associate, Veterinary Diagnostic Laboratory at Iowa State University, told Pig Health Today. However, there are many factors sabotaging that goal.