Porcine circovirus associated diseases was originally identified as porcine multisystemic wasting syndrome, and was associated with an increased mortality rate in
The PCVAD name originated after the discovery of porcine circovirus Type 2 as part of the disease complex. More recently, swine practitioners began reporting an increased number of PMWS cases in finisher pigs. Through research trials and field cases, scientists discovered that the PCV2 disease was contributing to the increased presentation of PMWS in
those swine herds.
PCVAD is species specific, which means it doesn´t spread to other species.
According to Lisa Tokach, an Abilene, Kan., swine veterinarian, predictions are that every swine herd in the United States is "infected" with PCVAD, however, not all herds are "affected." "Infected" means that porcine circovirus Type 2 is present in the herd, but clinical signs may not be present, whereas, "affected" means that the herd is displaying symptoms associated with the virus.
Environmental conditions and the presence of other pathogens or diseases may contribute to disease expression. However, it is not yet clear what drives the disease.
PCVAD depletes an animal's lymph node system, leaving the pig with no defense against other pathogens. When the pig becomes infected with another pathogen or disease, its body can´t defend itself, so most PCVAD-affected pigs die, says Tokach.
"We´re still learning a lot about PCVAD, but we do know that it is a viral condition in swine related to PCV2, and it seems to have a wide variety of symptoms," she says.
She has been working closely with swine producers and a team of Kansas State scientists who are studying PCVAD and other infectious diseases to find possible solutions.
The scientists are conducting field studies and laboratory diagnostics, developing a disease model, and working with swine producers to test PCV2 vaccines, says Bob Rowland, virologist for the College of Veterinary Medicine.
"This is definitely a new approach to infectious disease research, in which we´re working closely with vets and producers," says Rowland. "Much of my success in research
depends heavily on field studies. For the first time, we´re getting e-mails from producers and are developing relationships with them. This has given us a sense of urgency to develop solutions so producers can recover their profitability. Their long-term success is dependent on our research success."
Scientists expect to have the vaccination study finished in about a month, but they are not sure when a vaccine will be available in sufficient amounts for producers to purchase.
"From a practitioner point-of-view, I´m seeing farmers lose up to 20 percent of their finisher pigs," says Tokach. "This disease is not only economically devastating, it is emotionally devastating, too. That´s why we´re working so hard to find a cure or vaccine."
One commercial vaccine is available, but in limited amounts.
The disease seems to be spreading rapidly and randomly, making it difficult to predict where it may turn up next.
Some symptoms of PCVAD include anorexia, rapid weight loss, generally unhealthy pigs, skin discoloration or lesions, respiratory problems and diarrhea. For a look at a brochure offering management practices to reduce the risk of a PCVAD outbreak, follow this link (PDF file).
Anyone suspecting a problem in his/her herd, should work with a veterinarian to collect tissue and blood samples to be tested, says Tokach.
Source: Kansas State University