Fw: PRO/AH/EDR> West Nile virus, raptors - USA (02)

Jim McGough jmcgough at blarg.net
Fri Sep 27 18:08:39 PDT 2002


----- Original Message -----
From: "ProMED-mail" <promed at promed.isid.harvard.edu>
To: <promed-ahead-edr at promedmail.org>
Sent: Wednesday, September 25, 2002 8:11 PM
Subject: PRO/AH/EDR> West Nile virus, raptors - USA (02)


>
> WEST NILE VIRUS, RAPTORS - USA (02)
> ***********************************
> A ProMED-mail post
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> International Society for Infectious Diseases
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>
> Date: Wed 25 Sep 2002
> From: ProMED-mail <promed at promedmail.org>
> Source: Philadelphia Inquirer, Wed 25 Sep 2002 [edited]
> <http://www.philly.com/mld/inquirer/4144030.htm>
>
>
> Influx of Sick Raptors
> ----------------------
> Across the region, wildlife rehabilitators are seeing an influx of
raptors,
> especially great horned owls and red-tailed hawks, with apparent
> neurological problems. Veterinarians treating the birds think they know
> what the problem is: West Nile virus is hitting the raptor population.
> "There's a very definite, substantial die-off of birds of prey in
> Pennsylvania," said Daniel Brauning, an ornithologist with the
Pennsylvania
> Game Commission.  "There's a serious problem afoot here," echoed Jeanne
> Woodford, president of the Woodford Cedar Run Wildlife Refuge in Medford,
> Burlington County, which in the last month has treated at least 10 raptors
> suspected of being infected with West Nile virus. This month alone,
> Tri-State Bird Rescue in Newark, Delaware, has treated 9 great horned owls
> and 3 red-tailed hawks. The rescue workers say they are confident about
> their West Nile virus diagnosis, but cannot be sure of it because their
> non-profit centers cannot afford to conduct definitive tests, and publicly
> funded labs are backed up.
>
> What concerns wildlife officials most, perhaps, is that while crows and
> blue jays, the birds most commonly affected, are numerous enough to
> withstand population losses, many raptor species are not. Pennsylvania
> officials are especially worried about the potential impact on eagles,
> peregrine falcons, ospreys and short-eared owls, all of which are either
> endangered or threatened in the state. "In those lower populations, 10
> birds is significant," said Jerry Feaser, a game commission spokesman.
> Nationwide, all but the falcons have been identified as species that have
> tested positive for West Nile virus. Largely due to an aggressive
> restoration program, Pennsylvania now has 62 pairs of bald eagles, which
> produced 87 young this year. If West Nile virus was to hit the birds,
> Brauning said, "it could set the restoration program back 15 years."
>
> Researchers are not sure why they are seeing an effect on raptors. They
> theorize it could simply be a matter of these large birds being more
> visible, so when they get sick people notice. Or, said Wendy Looker,
> director of Rehabitat, a York County raptor rehab center, it could relate
> to raptors being at the top of the food chain. A sick raptor might be
> around longer to be noticed as compared to, say, a tiny songbird that
would
> be picked off by a predator at the first sign of weakness. Looker has seen
> pockets of sick raptors. In York County, the numbers are low, she said. In
> Dauphin County, right across Susquehanna River, "we have received as many
> as 8 birds in 36 hours." Still, the situation in Pennsylvania and New
> Jersey is nothing like that in the Midwest, particularly Ohio, where West
> Nile virus has killed up to 1000 raptors since mid-August.
>
> Now, with the fall migration just beginning, officials are alerting
> researchers along the Mississippi flyway and into Mexico and Central
> America so that they can develop better surveillance programs. "We are
> expecting the virus will show up down there," said Emi Saito, a veterinary
> medical officer with the National Wildlife Health Center in Madison, Wis.
> The virus was first detected in New York City in 1999, and "this is the
> first season we've experienced such a high morbidity among raptors," Saito
> said. "Is it that West Nile virus has established itself so well that the
> birds are being exposed? Or is something else going on that weakens the
> birds? Has the virus changed in some way?" The virus "could be more
> prevalent or more virulent or possibly both," said Len Soucy of the Raptor
> Trust in Morrisville, N.J.
>
> The national wildlife lab has begun testing dead birds for a host of
> potential problems. "We want to find out, even if they test positive for
> West Nile virus, whether that's what's killing them," Saito said. The
spike
> in sickened raptors may say something about how the virus is spreading. So
> far, all researchers know is that it spreads by bites from mosquitoes
> infected with West Nile. But they are wondering now whether it can also be
> transmitted to birds who ingest mice or other small animals with the
virus.
>
> Researchers also are looking at a species of blood-sucking fly, found in
> small numbers on all wild birds. [This may be a reference to ectoparasitic
> flies of the family _Hippoboscidae_. - Mod.CP] Looker said rehabbers are
> finding hundreds of them on sick birds. A state lab has confirmed that
> flies she collected were infected. But what does that mean? "Are the flies
> a host? Can they transmit?" Looker said. "There are more questions than
> answers."  Some facilities, including the Raptor Trust and Rehabitat, have
> begun to experiment with the only West Nile vaccine in existence -- one
for
> horses -- administering it in low doses to resident raptors used for
> educational purposes. "We're pretty much shooting in the dark," Soucy
said.
> They think the vaccine is innocuous. Then again, they're not sure whether
> it's protecting the birds. What they would like to see is for some
infected
> wild birds to recover, which would suggest they had built up antibodies
> that could be passed along to others in the population. But so far, the
> birds are either dying or do not recover enough to be released, said
Sallie
> Welte, a veterinarian at Tri-State. This, despite "intensive supportive
> care" that includes Vitamin B injections, anti-fungal medication,
> antibiotics, echinacea as an immune stimulant and a diet heavy on liquids
> and easy-to-digest foods."When its gets into an area where there are no
> natural immunities, that's when it hammers the wildlife,"  Soucy said.
>
> Actually, he is almost more worried about the public reaction than about
> West Nile virus. "I don't want to... regress 40 years and start spraying
> the whole world with DDT." "I think the point is that we are going to have
> to learn to live with this disease, as we have had to learn to deal with
> the AIDS virus and the common cold," he said. Feaser agrees. "Bottom line,
> although we will be monitoring the impacts, if any, of West Nile virus on
> the bird and mammal populations, there is basically nothing that can be
> done to intervene in the process... . Wildlife  populations will have to
> adapt to the disease."
>
> [By Sandy Bauers]
>
> --
> ProMED-mail
> <promed at promedmail.org>
>
> [This article highlights some of the unresolved problems in this alarming
> situation: namely, the high morbidity observed in 2002 in contrast to
> previous years; the uncertain identity of the potential vector - mosquito
> or ectoparasite; an apparent regional variation in morbidity and
mortality;
> the protective efficacy or not of immunization employing an equine
vaccine;
> and the unavoidable reliance on circumstantial evidence in the diagnosis
of
> West Nile virus infection. - Mod.CP]
>
> [see also:
> West Nile virus, raptors - USA 20020912.5289
> West Nile virus, hippoboscid flies - USA (PA)  20020925.5395 ]
> ..........................dk/mpp/cp/mpp
>
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