CARTHAGE, Ill. — Colder temperatures that are settling over
the Midwest are the next question mark for those monitoring the spread of PEDV,
porcine epidemic diarrhea virus.
“We have not gone through a winter with the virus,” said Dr.
Joe Connor of Carthage Veterinary Services, based in Carthage.
Cold weather and harvest-time activities, including emptying
manure pits and lagoons, could be contributing to the spread of the
swine-specific virus that mainly impacts suckling pigs.
“The virus has been environmentally hardy. It actually moved
in certain areas very actively this summer even when we had high temperatures,
but typically if we compare this virus to (transmissible gastro enteritis), and
looking at the environmental survivability, we expect that it’s going to stay
viable in below-freezing temperatures, so as we enter the cold season, then the
likelihood of it remaining viable — which then makes it easier to transfer —
increases,” said Connor, who noted that PEDV has been endemic in Asia for
several years and has survived cold temperatures.
Connor said there has been a spike in cases in recent weeks.
“The number of cases continues to increase, particularly in
the original active areas of Iowa, Oklahoma and then, more recently, in North
Carolina. We had a little bit of a slowdown in September, but in the last few
weeks, there’s been an increase in cases in many states of the Midwest,” he
Connor said that as of Oct. 6, Illinois had a total of four
cases and Indiana had 26 cases of PEDV reported.
Through Oct. 24, 828 case submissions tested positive.
However, Connor cautioned that the number likely includes repeated submissions
from the same herd and so would not accurately reflect the number of actual farm
Harvest time brings a perfect storm of factors that are
conducive to the spread of PEDV.
Connor said the virus survivability tends to be better in
“We’re finishing up and would have been in the middle of
harvest where we would have had maybe increased transmission. We’re removing
slurry from pits and lagoons, so we’ve got application occurring,” he
Connor said a movement of pigs to slaughter also could
contribute to the spread of PEDV, through transmission by vehicle.
“Those pigs may or may not be transmitting, but it’s likely
that the number of transporters, trailers, that would be positive or
contaminated with infected pigs has increased. That then increases the risk that
we have at any of the drop-off points, whether it’s a slaughter plant or a cull
sow plant or cull sow buying station,” he said.
Connor emphasized that the virus poses absolutely no threat
to humans or to the U.S. pork supply.
“It is absolutely no risk to humans and no risk to pork. It
is primarily only in the intestinal tract,” he said.
He also noted that manure being applied poses no threat, but
the danger lies in the movement of application equipment from farm to farm.
“It’s not the application process itself that is the risk.
It is that most of the industry uses applicators that would service a number of
facilities and so they are going to move from one facility to the next. By the
nature of our equipment, you are generally going to have a cycle pump or booster
pump that would go down into the pit that would have also been used in another
facility,” he said.
Connor said all producers, regardless of the type or size of
operation, need to look at their farms carefully to see where they can prevent
the spread of the virus through the movement of fecal material.
“I would like to emphasize that there are still steps that
we can take to minimize the transmission. Each individual producer should
critically evaluate each of those key areas, which would be transportation,
whether that’s weaned pigs, slaughter pigs, cull sows or light pigs. Secondly,
the movement of manure application equipment. Third, we’ve got to maintain
excellent isolation of incoming breeding stock, and we now have a serological
test, as well as PCRs, to clear those animals from isolation. Then, with their
own staff, adhere to showering, and if they don’t shower going in to facilities,
the Danish change, which is a change of boots or shoes, coveralls and washing of
hands,” he said.
The industry, including the National Pork Board, has put
funding toward research on every aspect of the virus, from how it got to the
U.S. to how it moves and survives.
“Because it is primarily transferred through the feces, any
method that transfers fecal material would be a method of introduction back into
the herd,” Connor said.
He said there has been good cooperation from the processing
side to help minimize the movement of the virus on the transportation side.
“There’s been tremendous cooperation trying to minimize what
we call the crossover traffic. In many cases, slaughter plants have initiated a
hot water wash, the last 10 feet of the loading dock. They have implemented an
electronic means of transferring the weight tickets so that the driver does not
have to walk across the area where other drivers have walked. There’s certainly
been an increase in the number of trailers that have been washed and dried,”
said Connor, who added there are recommendations for drying procedures.
“The ones that have drying bays, because this virus is even
more environmentally resistant to temperatures than (porcine reproductive and
respiratory syndrome), the recommendation is to dry those trailers at 150
degrees Fahrenheit for 20 minutes,” he said.
Connor advised producers to use materials and research
available through the National Pork Board’s www.pork.org website or through the
American Association of Swine Veterinarian’s website, www.aasv.org.
“There’s now updated information and brochures for
transporters, packing plants, manure applicators, sow buying stations and then a
white paper that summarizes how to deal with the virus in a sow herd as you look
at trying to eliminate that virus,” he said.
He urged producers in all types of hog operations to stay up
to date on the research and information. Connor has been involved in the working
groups through the National Pork and the AASV.
“Producers should procure all of that information, and they
can also, on www.pork.org, get the research studies that are in process. Those
are updated every two weeks to get the latest information as the studies start
to wind down,” he said.
Connor said even the operators of finishing facilities need
to be vigilant. While PEDV has the most impact and losses in suckling pig
populations, finishing facilities also could see outbreaks.
“They all need to pay attention. The difference is that,
just by nature of the virus, the high mortality is going to be in suckling pigs.
The wean-to-finish population or the nursery population or the finishing
population will have a very short-term diarrhea with almost no or low mortality
and quite good recovery. Whereas in the suckling pigs, because the herds have
not been exposed to the virus, the suckling pig mortality has generally been
almost 100 percent for a three-week time period and then it starts to taper off
over several weeks resulting in baby pig losses of equivalent to about five
weeks’ of production total,” he explained.
Connor said finishing facility operators need to maintain
“We still want our finishers to think about containment and
not move it to other facilities they would have onsite or offsite or to any
neighbors. Even though the mortality is generally low, the pigs will go through
a period of diarrhea for two to four days,” said Connor, who said finishing
facilities have the opportunity to be an endpoint for the virus.
“The important thing for the finishing side is if they can
contain it to that building or that population of pigs, when they empty that
building, then they’ve got the opportunity to eliminate that virus out of the
building, but it will take more work, more sanitation, a better, more intense
disinfection, but then the next turn of the barn, if they have a negative source
coming back in there, then they will have a facility that is clean and a
population that would remain negative through the flow,” he said.
He noted that one published report tracked the virus to
Anhui province in eastern China.
“There was a published report that it appears to have at
least originated from the Anhui province. We have known since the first cases
that the virus was 99.46 percent similar to the virus that was identified in
China. This is just a further refinement of identifying a little closer the
province or location,” he said.
The ultimate goal of the industry is to stop the spread of
the virus and eliminate it. Connor said it will take the cooperation of all
sectors to do that.
“I’d encourage them to really critically look at the
information that’s out and let’s help ourselves and see if we can contain it and
eventually move toward elimination,” he said.