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

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



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From: "ProMED-mail" <promed at promed.isid.harvard.edu>
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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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