The National Pork Board has funded a six-month study at Ohio State University's (OSU) College of Food, Agricultural, and Environmental Sciences to develop a unique way to test and trace the spread of porcine epidemic diarrhea virus (PED) virus. PED virus, first detected in the United States this spring, has spread to 15 states and impacted hundreds of hog operations.
OSU virologists Linda Saif and Qiuhong Wang are involved in a project that involves growing the virus in the lab and using this material to develop a serological test, which will allow scientists to determine how widespread PED virus is in the U.S. swine population.
“Serology allows you to trace the history of the outbreak through antibodies,” says Saif, an international expert on viral diseases of swine and cattle and a distinguished university professor in the college's Food Animal Health Research Program, part of the Ohio Agricultural Research and Development Center. “This is very important in this case because we don't know how and where PED virus got into the United States, and how it is spreading across state lines.”
Growing the virus in cell culture and developing a serological test are also important steps for the future development of a vaccine against PED virus, Saif says. Currently, there is no vaccine or treatment for the disease. Biosecurity measures are the only way to protect herds.
PED virus belongs to the coronavirus family, which is known to cause respiratory and intestinal diseases in mammals and birds. It has been present in Europe since the 1970s and in Asia since the 1980s. PED virus causes intestinal disease in swine, especially young pigs. It is transmitted via feces or insects contaminated with feces.
PED virus does not sicken humans and does not impact the safety of pork products.
“The entire U.S. swine population is at risk of this disease because it doesn't have any immunity to the virus,” Saif says. “We have seen 50-100% mortality in baby pigs. Adults pigs only show mild illness, but the problem is that the pigs can become carriers of the virus and spread it to other pigs.”
Saif says PED virus is difficult to identify because its symptoms, which include vomiting, diarrhea, poor appetite, dehydration and depression, are almost identical to those of transmissible gastroenteritis virus (TGE), another coronavirus that Saif has researched extensively and which has been present in the United States since the mid-20th century.
“The only way to tell these two viruses apart is through laboratory testing,” Saif says. “Producers and veterinarians who observe these symptoms are being encouraged to submit samples for testing so that we can better determine the extent of the outbreak.”
Saif says having enough PED virus samples available is also important for researchers such as she and Wang who are working on ways to learn more about and combat this new disease.
“This virus is difficult to grow in the lab,” she says. “We need all the samples we can possibly get.”
Ohio producers and veterinarians can submit samples to the Ohio Department of Agriculture's Animal Disease Diagnostic Laboratory, which has PED virus tests available and has been instrumental in providing Saif and Wang with virus material to conduct their research.
The American Association of Swine Veterinarians advises producers to follow these recommendations to decrease the chances of their herds becoming infected:
--Pay particular attention to anything sourced internationally, including feed ingredients of foreign origin.
--Be diligent about personnel who have traveled abroad and visitors from overseas who may be carrying the disease.
--Limit traffic (people and equipment) onto the farm.
--Thoroughly clean and disinfect anything coming onto the farm, especially animal transport vehicles.
--Take care when disposing of dead stock, particularly if using a communal disposal method.
--Isolate newly arriving animals and continue vet-to-vet discussions about animal health at the herd of origin.
Saif adds that swine producers are not the only ones that should be vigilant about PED virus.
“With fair season upon us, fair boards and 4-H clubs need to take precautions and monitor for the disease,” Saif says. “You will have a conglomeration of animals from many different farms coming together at one place, and people going back and forth. This could help spread the disease among pigs even further.”