Researchers continue to search for PEDv answers
By Jennifer Carrico
The introduction of porcine epidemic diarrhea virus into the United States in May 2013 has caused severe harm to the pork industry, with nearly 7,000 operations affected in 30 states.
Lisa Becton, director of swine health and information for the National Pork Board, said the research continues to develop producer resources and containment strategies. Becton spoke during a standing-room-only session at the World Pork Expo in Des Moines, Iowa.
“When the virus became a problem last year, the National Pork Board’s swine health committee met to help make decisions on what research needed done and what the timeline could be to get results,” Becton said. “A strategic task force was also formed with input from the American Association of Swine Practitioners, the National Pork Producers Council, the National Pork Board, along with state and international associations to see how to best handle this outbreak.”
The initial research started in June 2013 to determine what the virus looked like, how it affected the hogs, the environmental stability and what kind of diagnostic test would be the best option to determine if the disease was present.
In the fall of 2013, sow immunity was a high priority for researchers in order to determine how long immunity lasts and what type of immunity is given to the piglets. Other concerns were risk factors of feed and if the virus is present in feed ingredients.
“Since we needed information fast on PEDv, we asked for research results within six months, when normal research would take 12 to 18 months,” Becton said. “The exception was with sow immunity, as we knew that research would take about 12 months to complete.”
The severity of the PEDv symptoms is age dependent, with neonatal piglets being the most affected and having the highest fatality rate. Becton said the diarrhea symptoms start about two to three days post infection and stops after 10 days post infection. Fecal virus shed starts at 24 to 48 hours and peaks at five to six days post infection, but it can shed for up to 35 days post infection.
Research shows that the virus is not exhaled from the pigs but still could spread in the air.
“Since the virus is difficult to grow in a petri dish, developing a vaccine to fight it is also difficult,” Becton said.
Citing a source of the virus on each farm can be very difficult. The main way PEDv spreads is via fecal-oral exposure. While a diagnostic test needed to be developed quickly, researchers wanted to be able to develop a test for multiple viruses.
Survivability of the virus was an issue as well. Numerous parts of the system had to be looked at to determine where the virus was lurking. These included feed, water, type of feed, storage, and manure slurries.
Initial research results show that the virus survives longer at cooler temperatures in both manure and feed. PEDv was detected in drinking water for up to seven days.
“Research was also conducted on how long the virus can survive in a metal trailer. Extremely hot water wash outs of 160 degrees Fahrenheit can kill the virus after about 10 minutes. Leaving the trailer set for seven days at a room temperature of at least 68 degrees Fahrenheit will also kill the virus,” Becton said.
With numerous ways for the disease to spread, Becton said the closer hog farms are to each other, the higher likeliness for one to have the disease if another does. Currently several studies are being conducted to see if the virus can be carried in the wind.
Transportation continues to be an issue. Virus was found in all packing plants in the Midwest and buying stations in North Carolina. Vehicles seem to be a vector for the virus as well as loading chutes and other areas where manure is found.
“Cleanliness of barns and good biosecurity are very important to helping reduce disease load,” Becton said.
Research priorities have been set for 2014, which include length of immunity, feed sources and transportation. Information is starting to be collected on sow immunity and comparing it to immunity in other diseases.
“Research is being conducted on feed ingredient treatments to see if how feed is stored, how it is prepared, and how it is delivered to see if any of those are affecting the virus,” Becton said.
Since the discovery of PEDv, pork producers have also seen a rise in the cases of porcine deltacoronavirus.
“We want to be able to determine if we can find out more about these other viruses at the same time and if there are similarities,” Becton said.
The complexity of the virus has researchers busy looking at all angles of the disease and how it is affected by other factors in the environment.
“PEDv seems to be a seasonal virus, with fewer cases in the summer months, but that doesn’t mean that it will go away,” Becton said. “We will continue to conduct research and get results out as quickly as possible to prevent the increase in disease during the cooler months.”
Jennifer Carrico can be reached by phone at 515-833-2120 or by email at firstname.lastname@example.org.