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Date: Mon, 30 Sept 2002
Posted by: Lois Levitan (lcl3@cornell.edu)

(1) West Nile Bird Vaccine Breakthrough, Sept 20 2002 News Release, American Bird Conservancy
(2) Role of WNV in mortality of raptors and other birds, various comments, news article, info re: WNV-positive Hipposboscid flied (bird ectoparasites)

(1) WEST NILE BIRD VACCINE BREAKTHROUGH

[Thanks to Cathy McDuff for alerting us to this Sept 20, 2002 News Release from the American Bird Conservancy (http://www.abcbirds.org/media/releases/vaccine_breakthrough_release.htm. See also "WNV Vaccine for Geese," a WestNileVirus-L posting from Feb 7, 2002, (http://www.cfe.cornell.edu/ERAP/WNV/WNV-LArchive/2-7-02b.html)]

American Bird Conservancy (ABC), in partnership with the American Zoo and Aquarium Association (AZA), and with support from Disney Wildlife Conservation Fund, has led efforts to develop a West Nile vaccine for birds. The first round of trials, carried out by The Centers for Disease Control and Prevention (CDC) in Fort Collins, Colorado, have now been completed with encouraging results: inoculated birds showed a 60% increase in survival rates over unvaccinated birds in lab tests.

The virus, first discovered in the U.S. in 1999 has been responsible for approximately 60 human deaths. The toll on both wild and captive birds has been enormous. The response of birds to West Nile is highly species specific, with crows, Blue Jays and hawks among the worst hit. In total 111 species have now been recorded as killed, but because of the elusive behavior of sick birds and the efficiency of scavengers, most dead birds are never found. Those that have reached local laboratories for analysis represent only the smallest fraction of birds actually killed - a number thought to be in the tens of thousands by researchers.

Concern among zoos and captive breeding facilities that some endangered and threatened species both in the wild and those being bred for reintroduction could be impacted, has led to the effort to develop a vaccine.

"We are very pleased with the initial tests and believe this could be an effective tool for protecting some of our most endangered birds such as Mississippi Sandhill Cranes and California Condors," said Dr. Patti Bright, a veterinary epidemiologist, and Director of ABC's Pesticides and Birds Campaign. "We are now looking forward to conducting field trials at participating institutions to see how the vaccine performs in real-world situations, outside of the laboratory."

The American Crow suffers close to 100% mortality rates in the wild when infected by West Nile virus and so was chosen as the test species for the vaccine trials. At the CDC lab, scientists noted a reduction in mortality rates of 60% by use of the new recombinant DNA vaccine.

Paralleling the development of the recombinant DNA vaccine in the U.S., scientists in Israel (where the disease was first discovered) have been working on a 'killed' vaccine, which has also showed early promise in laboratory trials. Concurrently, researchers at CDC, in collaboration with Colorado State University, United States Army Medical Research Institute for Infectious Diseases, Harvard University, and Temple University, are investigating the manufacture of an oral vaccine for use on wild bird populations. Recent successes with injectable vaccines may lead one step closer to this goal.

Additional funding for this project has been provided by several AZA member institutions: including the Dallas Zoo, Brookfield Zoo (Chicago), Franklin Park Zoo (Boston), Houston Zoo, Saint Louis Zoo, and the Wildlife Conservation Society, headquartered at the Bronx Zoo (New York City).

Contacts:

Gavin Shire, ABC, gshire@abcbirds.org, (202) 452-1535 x 207
David Daigle, CDC, drd4@cdc.gov, (404) 639-3286
Michael Hutchins, AZA, Mhutchins@AZA.org, (301) 562-0777 x 240

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(2) VARIOUS COMMENTS ON ROLE OF WEST NILE VIRUS IN MORTALITY OF RAPTORS & OTHER BIRDS

(2a) BACKGROUND: On Sept 13 WestNileVirus-L posted a News Release from the Raptor Center, "Raptors Dying of West Nile Virus"(http://www.cfe.cornell.edu/ERAP/WNV/WNV-LArchive/9-13-02b.html). Subsequently a number of questions and issues have been raised about assessing the role of WNV in mortality of raptors and other birds. These have appeared on this listserv, on ProMED-mail, ArboBytes listserv, and in the Press.

The postings to West Nile Virus-L were on Sept 13 from Bob McLean (http://www.cfe.cornell.edu/ERAP/WNV/WNV-LArchive/9-13-02j.html), Sept 15 from Eleanor Kellon (http://www.cfe.cornell.edu/ERAP/WNV/WNV-LArchive/9-15-02.html ), Sept 18 from Emi Saito, responding to Bob McLean's question (http://www.cfe.cornell.edu/ERAP/WNV/WNV-LArchive/9-18-02c.html) and follow up comments from Bob McLean on Sept 23 (http://www.cfe.cornell.edu/ERAP/WNV/WNV-LArchive/9-23-02b.html).

Relevant Pro-MED postings have appeared under the subject lines "West Nile virus, hippoboscid flies" and "West Nile virus, raptors." Excerpts from relevant postings on Pro-MED and ArboBytes follow:

(2b) SOME ISSUES TO CONSIDER WITH RAPTORS, MORTALITIES & WNV (forwarded from ProMed posting Saturday Sept 28, 2002)

1. From: Richard A. French (french@uconnvm.uconn.edu) (Sept 27 2002)
Some Issues to Consider with Raptors, Mortalities, and West Nile Virus

(1) Both raptors and crows are susceptible to Eastern equine encephalitis virus (EEEV) as well as West Nile virus (WNV); (Am J Trop Med Hyg 66(4), 2002, 422-426). We have observed EEEV in raptors since surveillance for these arbovirus has increased.

(2) We have reported WNV in a raptor in the winter months (January in New England); (J Clin Micro 38(8), 2000, 3110-3111). Raptor mortalities may continue past the mosquito season. The mode of transmission is at issue (i.e., ingesting of prey, reservoir host, etc.).

(3) The role of ectoparasites in transmission of WNV in birds (hippoboscid flies have tested WNV positive) is worthy of exploration.

(4) The USGS National Wildlife Health Center's approach is excellent. Raptor mortalities need to be fully assessed, not just tested for WNV. Approximately 80 percent of the raptors we have received since WNV hit Connecticut in 1999 have not tested positive for WNV. We have observed trauma, mycotic disease (Aspergillosis), parasitic disease (primarily protozoan), bacterial disease (_Mycobacterium_ and _Salmonella_...), and our favorite: no significant lesions.

Richard A. French, DVM, MS, PhD
University of Connecticut
Department of Pathobiology, U-89
61 North Eagleville Road
Storrs, CT 06269

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(2c). From William Benner D.V.M. (BillB55@aol.com) (Sept 26, 2002) forwarded from ProMED posting Sept 28, 2002):

I am writing in response to the posting on supposed West Nile virus infection in raptors [see: West Nile virus, raptors - USA (02) 20020925.5401].

I am a veterinarian on Long Island, NY, and I treat wildlife, including raptors, on a regular basis. I would like to agree with the moderator's word of caution about "circumstantial evidence" being used to "diagnose" West Nile virus infection. Regardless of how certain anyone feels about the causes of disease and death in the raptors they are treating, my understanding from Dr. Ward Stone, State Wildlife Pathologist here in NY, is that many (most?) neurologic birds submitted for pathology are actually dead from pesticide toxicity. I have seen more neurologic raptors (Red-tailed Hawks and one Merlin) in the past few weeks as well, all emaciated and moribund. West Nile virus infection is certainly on the differential list, but I would never presume to diagnose the disease from the general neurologic signs noted. It would be tragic if there were even more avian pesticide deaths as a result of such conjecture. Hopefully Dr. Stone's lab and the National Wildlife Pathology Lab will be able to provide diagnoses, not suppositions, regarding these recent raptor deaths.

William Benner D.V.M.
Brookville Animal Hospital
Glen Head, Long Island, NY

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(2d) HIPPOBOSCID FLIES, relevance of these BIRD ECTOPARASITES to WNV:

1. Fwd from ArboBytes, Sept 22, posting from Lisa Reed, Dept Entomology, Rutgers University, NJ USA

"I heard a report (from a forward to BIRDBAND-L) that WN "was found" in hippoboscid flies. These are also known as louse flies or flat flies and are an avian parasite. The report was in conjunction with the high number of raptors dying in the Midwest. The only time I've come across them has been with Sharp-shinned Hawks. Does anyone have the original release that they could submit to ARBOBYTES? (It seems likely that if true, the flies merely represent what is going on in their host bird and is unlikely to play a role in transmission. Perhaps a hippoboscid lover can clarify.)

One reason why I'm asking for clarification is to keep the species list up to date: (http://www-rci.rutgers.edu/~insects/poswn.htm)

2. Fwd from ProMED, Sept 25, posting from John P. Maher (jmaher@chesco.org) dated Sept 24:

A pool of Hippoboscid flies has tested positive for West Nile virus in Dauphin Co (Pennsylvania). These flies are also called louse flies and are ectoparasites on birds and mammals. We have no idea regarding the importance of these insects because no work has been done with respect to Hippoboscid vector competence for West Nile virus. If they are capable of vectoring West Nile virus, they could be very important enzootic vectors in the wild in roosting areas and among nest mates. Birds in captivity, such as those in zoos and bird rehab centers, could also be disproportionately affected. The flies were collected from a symptomatic Great horned owl.

3. Fwd from ProMED, Sept 25, posting from Michael Hutchinson (mhutchinso@state.pa.us) in response to ProMED query:

Thank you for your question about the positive louse flies. We have sent 3 pools of Hippoboscidae for West Nile virus testing. The first pool of 5-6 specimens was taken from a Red Tail (RT) hawk that tested positive for WN - that pool tested negative. The second pool contained 5 specimens that were collected from a symptomatic Great Horned (GH) owl. That is the pool that tested positive through PCR as well as through virus isolation, indicated the presence of live virus. This is not surprising in that the specimens were visibly blooded. The results from a 3rd pool of non-blooded specimens are still pending. Future submissions of Hippoboscids from symptomatic birds will be held in the lab for 7-10 days to try to ensure complete digestion of the blood meal. Positive results from non-blooded insects will give us a better idea if the virus can survive within the louse flies. We will still be in need of vector competency studies to nail down the importance, or lack thereof, of this group. As for the question about the identity if the flies, they are in the genus Icosta and I'm waiting on literature to provide a species level identification. There are about 8 species in North America and they are bird biters.

Michael L. Hutchinson
Biologist - West Nile Virus Program
PA Department of Environmental Protection
(mhutchinso@state.pa.us)

(2e) INFLUX of SICK RAPTORS (fwd from ProMED-Mail, source, Philadelphia Inquirer, Sept 25 2002 [edited] (http://www.cfe.cornell.edu/ERAP/WNV/WNV-LArchive/9-23-02b.html)

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]

[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. - ProMED-Mod.CP]

-- 
Lois Levitan, PhD       Program Leader
Environmental Risk Analysis Program
Center for the Environment
213 Rice Hall, Cornell University
Ithaca, New York USA 14853-5601

Phone:   (607) 255-4765     Fax: (607) 255-0238
Email:	LCL3@cornell.edu

Program Email: envrisk@cornell.edu
Web:http://www.cfe.cornell.edu/ERAP

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WESTNILEVIRUS-L is an email discussion group for communication
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