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 The farm, through its veterinarian, publicly acknowledged on
Tuesday a repeat incident of Porcine Epidemic Diarrhea virus (PEDv),
which has killed up to 7 million pigs and pushed pork prices to
record highs since it was first identified in the United States a
year ago.
Matt Ackerman, whose veterinary practice is in southeastern Indiana,
told Reuters the farm's operators did not want to be identified but
authorized him to speak on their behalf.
The state and federal effort to stamp out PEDv has operated on an
assumption that a pig, once infected, develops immunity and will not
be afflicted by the disease again for at least several years.
Likewise, farms that had endured the disease were not known to
suffer secondary outbreaks.
But a year after the virus was identified, repeat outbreaks have
occurred at farms but not been publicly confirmed before now. These
so-called secondary outbreaks are a challenge to efforts to stem the
disease, which is almost always fatal to baby piglets.
Nationwide, PEDv outbreaks seem to recur in about 30 percent of
infected farms, the American Association of Swine Veterinarians told
Reuters, confirming for the first time the likelihood of repeated
outbreaks.
Hog futures reached a record high last month and are up more than 26
percent at $115 per hundredweight since the first U.S. outbreak was
confirmed last summer. Retail pork prices also have set new records,
and a wave of re-infection could cause even more losses to the
nation's hog herd.
In the Indiana case, genetic sequencing showed the "exact same
strain" of PEDv hit pigs at the Indiana farm in May 2013 and again
in March 2014, said Ackerman, who collected samples from the farm.
Piglets born to sows that were infected for a second time have a
death rate of about 30 percent, compared to near-total death loss
among newborn piglets during the first outbreak, he said.
The incidence of the disease “re-breaking” on farms after it
appeared to have been wiped out, indicates that the risk for ongoing
severe losses from the virus is bigger than previously expected. The
lack of long-term immunity also means hog producers must keep up
strict bio-security measures to fight the disease, which has already
spread to 30 states.
REASONS FOR RE-INFECTION UNCLEAR
Veterinarians and others have been unable to predict the duration of
immunity to PEDv in hogs following exposure, in part because the
disease had never been in the United States before last year.
Ackerman had thought hogs would have a natural immunity to PEDv for
three years after being infected because that is the case for a
similar disease called Transmissible Gastroenteritis.
"Just because a farm broke with PEDv last year doesn't mean that
they are protected from re-breaking with it this year," he said in a
telephone interview.
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Ackerman said he did not know why the female pigs, or sows, on the
Indiana farm were re-infected after being exposed to the virus
during the original outbreak last year. At the time, they were about
six months to a year old. The sows are having piglets and passing
limited immunity on to their offspring, he said. The farm "does an
excellent job of sanitation," he said. "That's why it's so hard to
figure out why they're struggling with it."
The repeat case of PEDv in Indiana puts to rest gossip about a
re-break in the state that has passed from one Midwest farmer to
another for weeks. Producers are on edge because no vaccine has yet
been able to completely protect pigs from the disease.
PEDv is transmitted from pig to pig by contact with pig manure,
which contains the virus. It can be transmitted from farm to farm on
trucks, and many veterinarians also believe it is spreading through
animal feed.
Harry Snelson, a veterinarian who represents the American
Association of Swine Veterinarians, said repeat occurrences tend not
to be as severe as the first outbreak, although farms are still
losing pigs.
One potential reason for repeat outbreaks is that high levels of the
virus, found in fecal material, overwhelm hogs' natural immunity,
Snelson said.
"It probably doesn't take a whole lot to override the level of
immunity that we're getting," he said. "Obviously immunity is a key
part of our being able to control the spread of the virus."
Preliminary results from studies on immunity, directed by the
National Pork Board, confirm "immunity does appear not to be very
long lived," said Lisa Becton, director of swine health information
for the board. The board has collected more than $2 million for
research on PEDv.
The re-breaking is causing concern among farmers and meat packers
across the country, as the PEDv outbreak continues to spread with no
definitive solution in sight.
"If you have that disease, it causes a huge death loss, and then you
get it again," said Josh Trenary, executive director of Indiana
Pork. "It's pretty clear why it would be concerning."
(Reporting by Tom Polansek; Editing by Cynthia Osterman)
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