Friday, February 3rd, 2023
Friday, February 3rd, 2023

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PA: Expert: Rabies worse due to less trapping

University Park, Pa. – Shrinking furbearer habitat and a decline
in trapping may be impacting efforts to stem the spread of
rabies.

The average number of wildlife rabies cases in Pennsylvania
spiraled in the 1980s and hasn’t gone down since, despite a $9.7
million federal program to eradicate the deadly virus.

“Rabies would seem difficult to control among wild animals, and it
has decreased in Allegheny County to some degree, but nowhere near
the hoped-for goals of the ORV program,” said Pennsylvania Game
Commission veterinarian Walt Cottrell.

ORV stands for Oral Rabies Vaccine, a U.S. Department of
Agriculture initiative that involves aerial drops of vaccine-loaded
baits aimed at raccoons  – the most common rabies carrier. When a
raccoon bites into a bait sachet, it ruptures, delivering vaccine
to the animal’s mouth and throat.

In Pennsylvania, aerial drops are concentrated in western counties
in an effort to keep the disease from spreading westward to Ohio
and beyond. Raccoons in aerial-drop zones are also monitored. They
are trapped, anesthetized, and then blood-sampled to determine
whether they have ingested enough of the vaccine for it to be
effective.

“The highest response rate so far has been in the neighborhood of
30 percent,” Cottrell said. “A new vaccine is being used and they
hope the percentage increases.”

Raccoon rabies is a nationwide problem, although there is a
concentration of cases in the eastern United States, according to
the USDA, which selected Pennsylvania as one of the first of 15
states for the aerial drop program because its mountainous
topography helps define vaccination zones.

But ORV hasn’t caused a decline in the number of cases, which have
ranged from 320 to 420 annually for the past 25 years. The
overwhelming majority have been raccoons, followed by skunks,
foxes, bats, deer and “others.”

In 1944, just one wildlife rabies case – an infected fox – was
reported, and in 1960, there were just nine cases in the wild,
involving foxes and skunks.

While the Game Commission doesn’t keep its own rabies statistics,
it does pay attention to the dynamics that may contribute to the
rabies problem, including trends in furtaker license sales, the
number of raccoons harvested each year, and the price of pelts,
which drives interest in trapping.

“Access to land where people trap is a big issue,” said Cottrell.
“That’s shrinking. Habitat in general is shrinking.”

As a consequence, raccoons and other animals are moving into cities
and suburbs, causing greater interaction with people, he
said.

“Humans play a role. If you know you’re attracting unwanted species
with a birdfeeder, it’s risky to continue. The same with trash and
unattended buildings – those can attract raccoons.”

Wildlife conservation officer Stephen Hanczar was called to an
empty house in Altoona June 22, because six raccoons had taken up
residence. Knowing he would have to return the following day,
Hanczar asked a gathering crowd of curious locals not to feed the
raccoons in the interim.

“I told them, ‘Don’t put anything out. Don’t feed them,’ and when I
went back the next day, I found a Styrofoam container with grubs,”
Hanczar said.

Animals conditioned to have humans fulfill their needs often cannot
be returned to the wild. In addition, Game Commission protocol
requires that, as a rabies vector species, raccoons captured in
residential areas be euthanized, Hanczar said.

One of the oldest-known diseases, rabies affects the central
nervous system and causes acute swelling of the brain. And while
two different wildlife rabies strains have been identified in
Pennsylvania – in raccoons and bats – rabies can be transmitted
from one species to another.

“Any mammal can get rabies. Bats can transmit it to bobcats, and
raccoons can give rabies to beavers,” Cottrell said. “When you
think about the common habitat they share, it’s not at all
surprising.”

This spring, a rabid beaver bit several anglers in southeastern
Pennsylvania, although cases among beavers are rare, Cottrell
said.

And more than 99 percent of exposures are through bites. “The virus
has to find its way to a nerve, and that’s anywhere there’s an
artery or vein,” he said. “The virus will travel those nerves until
it gets to the brain and once it does, it reproduces in huge
quantities, and the particles move out in the individual’s
body.

“One place it goes is to the salivary glands.”

Although an infection can incubate for weeks, months or even a
couple of years, once symptoms manifest, death usually results
within 10 days.

Laws requiring domestic animals to be vaccinated has helped reduce
rabies among dogs, cats, cows and horses from 897 cases in 1944 to
72 last year, with cats the species most afflicted.

However, that number may be edging upward, too. Fifty years ago,
there were zero to just a handful of reported cases among
domesticated animals in Pennsylvania.

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