Discussion: Low-risk bird flu found in Ill. wild ducks-USDA

[Harriet]

Low-risk bird flu found in Ill. wild ducks-USDA
29 Sep 2006 21:42:40 GMT
Source: Reuters

http://www.alertnet.org/thenews/newsdesk/N29251736.htm

WASHINGTON, Sept 29 (Reuters) - Wild Green-winged Teal ducks in central Illinois have tested positive for a low-pathogenic strain of avian influenza, the government said on Friday.

"Initial tests confirm that these wild duck samples do not contain the highly pathogenic H5N1 strain that has spread through birds in Asia, Europe and Africa," the Agriculture and Interior departments said in a statement.

Five of 11 samples taken from the ducks tested positive for the H5 virus subtype and one contained the H5 and N1 subtypes, they said. The samples were sent to a federal laboratory in Ames, Iowa, for further testing of virus strains.

The samples were collected on Sunday at the Rice Lake Conservation area in Fulton County, central Illinois. The ducks showed no signs of illness, which also indicates a low-risk strain of avian influenza.

As a precaution against the highly pathogenic H5N1 virus that has killed millions of fowl, the government has stepped up testing of wild birds. The Agriculture and Interior departments say they expect to find additional cases of common strains of avian influenza that pose no risk to humans.

[Harriet]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

Release No. 0391.06
Contact:
Angela Harless, USDA (202) 720-4623
DOI Press Office (202) 208-6416

ILLINOIS WILD BIRD SAMPLES UNDERGO ADDITIONAL AVIAN INFLUENZA TESTING

WASHINGTON, Sept. 29, 2006 - The U.S. Department of Agriculture (USDA) and Department of the Interior (DOI) today announced a detection of the H5 and N1 avian influenza subtypes in samples from wild, migratory Green-winged Teals in Illinois. Initial tests confirm that these wild duck samples do not contain the highly pathogenic H5N1 strain that has spread through birds in Asia, Europe and Africa. These samples were collected from apparently healthy birds and initial test results indicate the presence of low pathogenic avian influenza (LPAI) virus, which poses no threat to human health.


The bird samples were collected on Sept. 24 in the Rice Lake Conservation Area of Fulton County, Illinois, through a partnership between USDA and the Illinois Department of Natural Resources as part of an expanded wild bird monitoring program. USDA and DOI are working collaboratively with states to sample wild birds throughout the U.S. for the presence of highly pathogenic avian influenza (HPAI). As a result of this expanded testing program, USDA and DOI expect to identify additional cases of common strains of avian influenza in birds, which is not cause for concern.

The ducks were showing no sign of sickness, which also suggests this is LPAI. Eleven samples were collected directly from the ducks. Of those samples, a pool of five samples tested positive for H5 and were sent to USDA's National Veterinary Services Laboratories (NVSL) in Ames, Iowa, for confirmatory testing. One of the five samples screened by NVSL tested positive for both H5 and N1. However, this does not mean these ducks are infected with an H5N1 strain. It is possible that there could be two separate avian influenza viruses, one containing H5 and the other containing N1. Confirmatory testing underway at NVSL will clarify whether one or more strains of the virus are present, the specific subtype, as well as confirm the pathogenicity. These results are expected within two to three weeks and will be made public when completed.

Low pathogenic avian influenza commonly occurs in wild birds and can be found in a number of duck populations including the Green-winged Teal. It typically causes only minor sickness or no noticeable symptoms in birds. These strains of the virus include LPAI H5N1, commonly referred to as "North American" H5N1, which is very different from the more severe HPAI H5N1 circulating overseas.

Duck populations, including Green-winged Teal, are commonly hunted. There is no known health risk to hunters or hunting dogs from contact with low pathogenic forms of avian influenza virus. Nevertheless, hunters are always encouraged to use common sense sanitation practices, such as hand washing and thorough cooking, when handling or preparing wildlife of any kind. DOI has issued guidelines for safe handling and preparation of wild game.

For more information about USDA's efforts and research related to avian influenza, go to http://www.usda.gov/birdflu. For more information about Interior's efforts and hunter education program, go to http://www.doi.gov/issues/avianflu.html For information about the federal government's overall efforts related to avian influenza and human pandemic preparedness, go to http://www.avianflu.gov.

http://www.usda.gov/wps/portal/!ut/p/_s.7_0_A/7_0_1RD?printable=true&contentidonly=true&contenti d=2006/09/0391.xml

[Harriet]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

Always conveniently released to the media on Friday afternoon when noone is paying too close attention. This has been the pattern.

[MHSC]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

They always fail to mention that low path can mutate into high path.

[Harriet]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

Migration/Winter Range:

Like many dabblers, Green-winged Teal leave their northern breeding grounds in late August/early September to travel to their wintering grounds, which are as vast as their breeding grounds. Found in coastal Alaska, British Columbia, most of the U.S. States, parts of the Caribbean as well as parts of Central and South America, the Greenwing spreads far and wide throughout the Americas. Traveling in flocks larger than those of similar species, the Green-winged Teal will be on the move for weeks or months to its wintering grounds to prepare for another breeding season, and perpetuation of the species.

http://www.borealbirds.org/birdguide/BD0392_species.html

Alaska

[Sally Furniss]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

In terms of mutation what is the difference between low path and high path?

[Harriet]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

On present understanding, H5 and H7 viruses are introduced to poultry flocks in their low pathogenic form. When allowed to circulate in poultry populations, the viruses can mutate, usually within a few months, into the highly pathogenic form. This is why the presence of an H5 or H7 virus in poultry is always cause for concern, even when the initial signs of infection are mild.

http://www.who.int/csr/disease/avian_influenza/avian_faqs/en/index.html#isit

[AlaskaDenise]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

I believe it's multiple amino acids in the HA (added: cleavage site).

They also fail to mention that LPAI is in 10-15% of wild fowl globally and 20+% in Canada last year.

.

[HenryN]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

In terms of mutation what is the difference between low path and high path?

HA cleavage site.

[Harriet]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

MI: Mute swan

MD, PA: Mallards

MT: Northern Pintails

IL: Green-winged Teals

CA: Duck(s) dead, am inquiring as to the type

[AlaskaDenise]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

http://www.suntimes.com/news/metro/7...dflu29.article

Bird flu detected in wild ducks thought to be harmless



<!-- Article Publsih Date -->September 29, 2006
<!-- Article By Line -->BY THE ASSOCIATED PRESS

<!-- boxscore --><!-- Article's First Paragraph -->Tests have found suspected bird flu in wild, migratory ducks in Illinois, but federal officials said Friday it's not likely to be the deadly Asian subtype they fear could reach North America.

Initial test results suggest the ducks had a strain of virus that poses no threat to human health, officials from the U.S. Department of Agriculture and Department of the Interior said.

The ducks showed no sign of being sick, which also suggests a common strain of bird influenza. Results from further testing are expected within several weeks and will be made public, officials said.

Other states have also had wild birds test positive recently for the low-grade strain of bird flu, including Pennsylvania, Maryland and Michigan.

The samples from green-winged teals were collected on Sept. 24 in the Rice Lake Conservation Area of Fulton County in west central Illinois. The USDA and the Illinois Department of Natural Resources are cooperating to sample and test wild birds for the virus in a stepped-up monitoring program.

There is no known health risk to hunters or hunting dogs from the wild birds with the low-grade bird flu. Officials said hunters should always wash their hands when handling wildlife and cook foods thoroughly.

No birds in North America have tested positive for the Asian subtype of the bird flu virus known as H5N1, which has killed at least 148 people. The greatest number of deaths has been in Indonesia, according to the World Health Organization.

Wherever the disease has spread to humans, it has been through people's direct contact with the birds, mostly in Asia involving poultry. Experts fear the virus could mutate into a form that could be easily transmitted among humans, causing a worldwide pandemic that could kill millions of people.
<!-- start sidebar --><!-- Start Bottom Story -->

[MHSC]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

The ducks were showing no sign of sickness, which also suggests this is LPAI.

Forgive my failing memory but I thought ducks were silent carriers, and rarely show symptoms.

[Harriet]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

Flu Spread Is No Reason to Kill Wild Birds, Study Says

James Owen in London for National Geographic News

April 20, 2006

Wild ducks and other migratory birds could be important carriers of deadly bird flu, researchers say.

Even so, the infectious-disease experts say there is no solid basis for killing wild birds to protect poultry and minimize the risk of human infection.

The European team investigating the global spread of the H5N1 strain of avian influenza says certain duck species may be infecting wild bird populations.

Geese and wading birds are also possible vectors of the virus, the team says.

The team's study, to be published tomorrow in the journal Science, was led by Bj?rn Olsen of Ume? University in Sweden. Olsen runs Europe's largest wild-bird flu-monitoring program.

Studies have shown that influenza viruses in lake water, generally passed via bird feces, can stay infectious for up to 30 days.

The migration or feeding behavior of dabbling ducks could at least partially explain the spread of the H5N1 strain of bird flu, the researchers add.

This group of duck species includes mallards, teal, pintails, and others that feed at or near the surface, where viruses in water are most likely to be picked up.

Perhaps as a result, dabblers have the highest known rates of avian influenza infection, the study says. For instance, nearly 13 percent of mallards tested positive for bird flu. Other species tested include the American black duck (18.1 percent), blue-winged teal (11.5 percent), and northern pintail (11.2 percent). However, bird flu viruses appear to exist in ducks in a low-pathogenic form, meaning infection doesn't usually lead to severe illness and death.

Prime Hosts

"Dabbling ducks are for sure the prime hosts for low pathogenic viruses," said study co-author Ron Fouchier, a virologist at the Erasmus Medical Center in Rotterdam, Netherlands.

But the big question is, How much of our knowledge about these viruses can we translate to high-pathogenic viruses" such as the H5N1 strain of bird flu?

In poultry avian viruses can mutate into more virulent influenza strains, including H5N1.
If this mutated virus then finds its way back into wild populations, the birds could then spread the disease through migration.

Some scientists have argued that wild birds infected with HN51 would be too ill to migrate. Swans, for instance, appear to be particularly vulnerable to the strain.

"Swans apparently drop dead quite easily, but they are unlikely to be the vector because they are not going to fly very far if they are dead," Fouchier said.

But the study team says that some birds that have been purposely infected for the sake of research show that wild birds can survive H5N1.

"For some reason H5N1 has adapted so it no longer kills dabbling ducks," Fouchier said. This means the ducks may be able to spread the virus over a wide area. The study team says migratory geese may also be vectors, because they often graze in huge flocks, a practice that could encourage transmission.

Migrating ducks, the researchers add, "could provide an intercontinental bridge" for bird flu to North America, which has not yet had any known cases of H5N1. (See "Bird Flu Will Reach U.S. and Canada This Fall, Experts Predict.")
No Wild Culls Needed?

However, there is currently no reason to cull wild birds to control the spread of H5N1, the study says.

Wild birds, though, should be kept away from poultry, the researchers say.

"For all of the outbreaks that have ever been recorded for bird flu, it's clear that the poultry-production industry itself is responsible for most of the spread through poultry trade [and the] movement of people and equipment between farms," Fouchier said.

"You can prevent your chickens and turkeys from getting into contact with wild birds by simple biosecurity measures" such as keeping farm birds enclosed, he added (photo: "Ducks in Detention").

BirdLife International, a global bird-conservation group based in Cambridge, England, says culling operations may in fact spread the virus to noninfected areas by forcing diseased birds to disperse.

Last week Shafqat Kakakhel of the United Nations Environment Programme spoke at a conference on bird flu and migratory birds in Nairobi, Kenya.

"Blaming avian flu on bird migrations is misleading. And a 'quick fix' of culling migratory birds is certainly not the solution," Kakakhel said.

http://news.nationalgeographic.com/news/2006/04/0420_060420_bird_flu.html

[Sharpe]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

Forgive my failing memory but I thought ducks were silent carriers, and rarely show symptoms.

It varies, MHSC. Yes and no. Waterfowl are well adapted to having influenza viruses grow and divide continuously in their gut. They are usually asymptomatic as such. Hi-path strains of influenza which divide rapidly, however, can make the birds sick. This is probably unless they are also harboring mostly low-path strains that keep the high-path strain from going berserk. The problems started when the strain that arrived in Qinghai Lake most likely from India, for it had become so high-path that it killed the waterfowl it infected too. If birds have already gained immunity to a low-path H5N1 strain, they probably could harbor even the Qinghai Lake strain without any symptoms, but if that same virus was transmitted to a non-immune bird or animal, they would most likely die from it. As a result, I've noticed that usually, it's the younger geese, ducks, swans, etc., usually less than 1 year old, that die in large numbers when H5N1 strikes. This is probably because they have not yet gone through one or two migration cycles that expose them to enough low-path bird flu to give them the necessary immunity. Thus, when we hear that a farm of ducks in Vietnam or Thailand all die suddenly, it is usually because they are being bred for meat, and thus are all less than a year old. The neighboring lake however, with all it's older ducks would seem relatively unscathed, because they're carrying it asymptomatically.

[HenryN]

Re: Low-risk bird flu found in Ill. wild ducks-USDA

Commentary at

http://www.recombinomics.com/News/09290602/H5N1_Illinois.html