WASHINGTON, Dec.
9, 2015 - For generations, farmers have observed newborn and other young pigs
beset with tremors sometimes so severe that the pigs can’t suckle and they starve
to death. Often called “the shakes,” it has been a nervous system disorder with
no specific name and no cure, and otherwise healthy piglets most often survived
it.
Now researchers at Kansas State and Iowa State
universities, using next-generation sequencing, which quickly reads millions of samples
of genetic material, have identified the culprit virus and can tell farmers why their
little pigs shiver. At KSU’s Veterinary Diagnostic Laboratory, researcher
Benjamin Hause calls the newly discovered pathogen atypical porcine pestivirus,
or APPV.
Pestivirus
strains have long been linked to cow and sheep diseases and classical swine
fever in pigs. Hause reports his team had earlier discovered the new pestivirus
but didn’t link it to pigs until it got blood samples from two North Carolina
farms where 700 weaner pigs (age five to 14 weeks) had gotten the shakes so
severely last spring that they died.
The KSU lab also
tested pig blood samples from around the Midwest earlier this year and
discovered antibodies to the newly found pestivirus in 90 percent of samples.
That means most pigs have had the APPV pathogen in their lives, whether showing
symptoms or not, Hause explains. However, it seems often to cause tremors in
pigs at birth and/or during the first months of life.
Hause says he
hopes that KSU’s tests to detect the virus will lay groundwork to understanding
it better in time. The heavy losses to tremors in North Carolina are apparently
very unusual in the U.S., he says, but the potential for spreading quickly to
other farms and causing big problems across a region is unknown. “I hesitate to
say anything, because we lack information. In terms of how easily it spreads:
we have no idea,” he says.
At the ISU
Veterinary Diagnostic Laboratory, veterinarian Bailey Arruda agrees: “The
epidemiological data on this one is scarce.” Her team identified a nearly identical pestivirus earlier
this fall in blood samples from Iowa, Illinois and Missouri, causing the same
symptoms, except they were congenital, surfacing in newborns rather than in
weaner pigs. Also, the shaking didn’t usually kill the baby pigs. Like Hause,
she says, “Unfortunately, we do not know how it is transmitted.” USDA’s Animal
and Plant Health Inspection Service and the National Pork Board told Agri-Pulse that neither has information
on APPV, and deferred to KSU and ISU scientists.
Hause and Arruda
say farmers who see serious incidence of tremors in pigs can send blood samples
to their university labs to identify APPV. Arruda says at least one drugmaker
plans to develop a vaccination against this pestivirus strain. Meanwhile, for
affected young pigs, she recommends, “supportive care – make sure they get
colostrum and adequate milk intake” to avoid dehydration. “Just good husbandry
is your best bet,” she says.
In another swine
health development, KSU and University of Missouri researchers announced this
week that they have bred pigs that resist the porcine reproductive and respiratory
syndrome, or PRRS, a
scourge in U.S. herds for nearly 30 years.
The scientists,
together with Genus plc, a biotech company, succeeded in developing pigs
missing a specific gene, called “CD 163,” that the PRRS virus needs to thrive
in swine. Thus the virus, which slows swine growth and inhibits reproduction,
is itself blocked. "At the very least, the development of PRRS-resistant
pigs is a new tool for improving pig well-being and reducing economic losses,"
said Raymond "Bob" Rowland, KSU professor of diagnostic medicine and
pathobiology.
Bob Stallman,
president of the American Farm Bureau Federation, called the development “a
critical breakthrough” in hog farmers’ battle against the disease, which he
said causes an estimated $664 million a year in lost productivity.
“Being able to
fight this disease through advanced genetic technologies will mean healthier
animals, more efficient food production and more efficient risk management
options for producers,” he said.
#30
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