AlB-Lancaster Fanning, Saturday, February 8,1986
Pseudorabies:
Are we ‘ depopulating 9 pork producers as well as pigs?
BY JACK HUBLEY
LANCASTER While an army
of federal and state officials plunge
headlong into the battle with avian
influenza, a small detachment of
the state’s pork producers con
tinues to skirmish with a much less
renowned foe-pseudorabies virus.
Here in Pennsylvania, the seige
actually dates to the late 1970’s
when PRV, best known for its
prevalence in midwestem swine
herds, began showing up in the
northwestern part of Lancaster
County. The good news is that PRV
has gained little ground
geographically. The bad news is
that swine experts have found the
disease to be stubbornly resistant
to eradication efforts.
Part of the problem can un
doubtedly be attributed to PRV’s
apparent identity crisis. Symp
toms can range from no clinical
evidence to high rates of mortality,
says Strasburg pork producer John
Henkel. Henkel is currently the
director of a PRV task force
sponsored by the Pennsylvania
Pork Producers Council, and
charged with the duty of coming up
with a workable eradication
program.
An acute outbreak will usually
kill all of the baby pigs under two
weeks of age, as well as any cats
and dogs on the farm, says Henkel.
On the other hand, a herd suffering
from chronic bouts with PRV may
exhibit no noticeable symptoms at
all. The virus is also known to
cause stillbirths, abortions and
breeding problems, and infected
finishing pigs from 100 pounds and
up may suffer from pneumonia
and other secondary disease
problems. “It (PRV) opens the
animal up to other infections,”
notes Henkel.
“The real sad thing
about it » the vittims.
Financially and
emotionally it’s
» very stressful*
An acute Case of pseudorabies in the farrowing house oftei
results in 100 percent mortality in baby pigs under two week:
According to Bureau of Animal
Industry figures, 169 farms in
Lancaster and neighboring
counties have been placed under
quarantine since 1980. Currently 10
breeding herds and 11 feedlots are
under quarantine.
“We really do have a low in
cidence level,” says Henkel. “The
real sad thing about it is the vic
tims. Financially and emotionally
it’s very stressful.”
One producer who has had to
leam to cope with more than his
share of stress is Manheim
producer Mark Nestleroth.
Nestleroth was quarantined in
January, 1984, and, by November
of the same year he had lost 2,600
head of swine for a total equity loss
of $lBO,OOO. The heaviest losses are
accrued from the depopulation of
brood sows, says Nestleroth. “You
automatically lose $2OO a sow from
the inventory value of an operating
sow herd,” he says, pointing out
that the producer forced to sell a
bred sow for salvage value not only
receives a reduced price for the
meat, but loses an entire litter as
well.
Could Nestleroth have chosen a
less costly eradication method
than depopulation? At the time he
was quarantined, says the
producer, the Department of
Agriculture’s Bureau of Animal
Industry required that all infected
herds be cleaned up within eight
months, which automatically
eliminated other more time con
suming methods. “I tried to get an
extension until the spring of ’B5,
but it was rejected,” says
Nestleroth.
Bureau of Animal Industry
director Dr. Max Van Buskirk
contends, however, that a man
datory eight-month depopulation
deadline has never been in place.
“We asked them (producers) to
design a plan whose objective was
to get the herd cleaned up in eight
months,” says Van Buskirk. “But
we weren’t going to remove per
mits as long as they were im
plementing a plan. There was
never a cut-and-dried eight-month
requirement.”
Dr. David Thawley
“The only point we
were unable to
resolve was indemnity.”
The bureau chief says that he
received a PRV eradication
proposal from the Pork Council’s
task force last year and that his
bureau made a number of con
cessions on the kinds of control
programs they would accept.
“We’ve already implemented a
number of recommendations they
made,” he says. “The only point
we were unable to resolve was
indemnity.”
The lack of compensation
available to PRV victims does
indeed remain the program’s
major stumbling block. While
Nestleroth’s losses were con
siderable, he maintains that a
number of producers suffered
losses in excess of $200,000.
Because of the exorbitant costs
associated with total depopulation,
Henkel and the task force
recommended that the option be
considered only as a last resort.
Other possible options include test
and removal of infected pigs or
offspring segregation from the
infected herd.
Pseudorabies expert Dr. David
Thawley agrees that producers
should not be expected to shoulder
losses in the six-figure area. One of
five members of USDA’s PRV
National Technical Committee,
Thawley came to Pennsylvania
this week to examine the Penn
sylvania situation and make
recommendations for eliminating
the disease. Thawley was the
principle speaker at two meetings
held at Lancaster’s Farm and
Home Center on Monday and
Wednesday. He also met with
Secretary of Agriculture Richard
Grubb and Dr. Van Buskirk on
Tuesday.
At Monday’s meeting, Thawley
pointed dut that the cost of
eliminating PRV in lowa
operations has been about $9,000
per farmer, using the offspring
segregation method.
Reviewing the latest information
gleaned from the PRV pilot
programs taking place in five
states,(Pennsylvania is one of the
group that also includes lowa,
Illinois, Wisconsin and North
Carolina) Thawley asserted that
the “wherewithal” exists to
eliminate the disease.
Thawley noted that pigs
themselves are still considered to
be the primary source of infection,
and that wildlife is an unlikely
source of long-term spread of
PRV. While pigs shed the virus for
14 to 15 days following infection,
other animals are shedders for no
more than two days before death.
“You get it out of the pigs and you
don’t have to worry about wildlife
or other species,” he said.
Nor is manure a problem. “Body
wastes are not considered a
significant source of PRV,” said
Thawley. “Pigs don’t excrete it
(virus) in sufficient quantities to
infect other swine. The problem is
saliva.”
“It takes a lot of virus to infect a
pig,” said Thawley, “so en
vironmental contamination is not
as critical as in avian influenza or
foot-and-mouth disease. There is
no conclusive evidence that it
spreads in the air, except within
buildings and immediately outside
of buildings.” Thawley said that,
from his experience, a six-foot gap
between buildings is enough to
prevent the spread of PRV.
How long does it last in the en
vironment? Thawley said that a 30-
day period following cleanup is
sufficient downtime to insure that
the disease will be gone. Manure
pits will be free of virus if pumped
and left open for three days.
“A dead animal can
putrify considerably
and is still loaded with
infectious virus.”
“One thing that we’re worried
about is the fact that protein
protects the virus,” Thawley
emphasized. “A dead animal
(from PRV) can putrify con
siderably and is still loaded with
infectious virus.” A carcass can
harbor virus for at least two
months, he said.
Thawley is convinced that many
infections that seem to defy ex
planation were the result of small
animals containing active virus
being ground up in feed. He said
that infections occuring in isolated
herds managed under strict
biosecurity regulations have
convinced him that feed was the
most likely avenue of infection.
Going one step farther, Thawley
cautioned producers that using hog
feed containing meat scraps may
be risky. “Heat treatment in
processing should take care of the
virus, but the question is, do you
want to take the risk?” he said.
Although it does pose a serious
threat to herd health, the virus is in
fact very fragile, Thawley pointed
out. PRV is easily destroyed by
heat, dryness or “any sort of
alkalinity or acidity,’’ he said.
Reviewing the three cleanup
options submitted to the Bureau of
Animal Industry by the task force,
Thawley said that depopulation
may be advisable when more than
80 percent of the herd is infected,
there are no valuable genetic
strains involved and there are
multiple disease problems along
with PRV.
Offspring segregation can be
economically devastating,
Thawley said, but will permit
producers to salvage bloodlines.
The procedure also requires extra
buildings for housing baby pigs,
and producers run the risk of in
fecting the segregated herd if all
baby pigs are not tested before
segregation.
Test and removal of infected
pigs is the least costly of the three
MV
® r
options, Thawley said, and has
proved to be successful in herds
with less than a 50-percent in
fection rate. Thawley reported that
he “feels comfortable” with a test
and-removal program when
coupled with vaccination.
But Thawley also cautioned that
vaccination should not be con
sidered a miracle cure. While
vaccine will help to suppress a
“major clinical outbreak,” it will
not prevent infection. “I recom
mend it,” he said, “but only the
killed (vaccine).”
“We cannot permit
the use of vaccine
except in cm infected
herd to reduce
disease losses
Because vaccinated pigs test
positive for PRV, the use of vac
cine has always been controversial
in Pennsylvania. While pigs
treated with the “killed” vaccine
will test negative for PRV after
four to six months, this is not the
case when a “modified live”
vaccine is used. The use of any
vaccine in Pennsylvania is
prohibited except by special
permit from BAI.
“We cannot permit the use of
vaccine except in an infected herd
to reduce disease losses,” says
Van Buskirk. “And we’d still insist
that the infected animals have to
be depopulated.” Van Buskirk
emphasized that the bureau will
not permit the use of vaccine on
negative herds as a preventive
measure.
After examining Pennsylvania’s
PRV problem, Thawley recom
mended that eradication efforts
should be instituted on a case-by
case basis. “If I were in your
position, I’d propose that the state
hire a swine practicioner to work
with these herds and develop plans
for them,” Thawley told
producers. “You’ve got such a |
small number of herds that you’d j
probably be better off with one
private practicioner.”
But the number of reported PRV
herds may not be an accurate
reflection of the scope of the
problem, noted one producer. ,
Faced with the possibility of total
depopulation without an indemnity
safety net, it’s likely that the
owners of some infected herds ,
have elected to keep their
problems to themselves.
Although Van Buskirk said that,
his bureau has made no decisions
nor taken any action in response to
his meeting with Thawley, he
noted that there is hope that in
demnification could become a |
reality. There has been at least one,
such bill introduced in the state
legislature, and the Governor’s
proposed budget for 1986-87 in- j
eludes a provision for $125,000 to be
added to the $225,000 animal in
demnity fund. The increase would
be earmarked specifically for PRV
indemnification.
According to John Henkel, the
Pork Council has no intention of
letting the issue fade away. “We're
going to keep working on some way
to find funding,” he concluded.