Maryland - U.S. finds low-risk H5N1 bird flu strain in ducks

[Harriet]

By Charles Abbott

WASHINGTON (Reuters) - Mallard ducks in Maryland have tested positive for bird flu, apparently a common, less pathogenic strain that poses no risk to humans, the U.S. Agriculture and Interior departments said on Friday.

The H5N1 avian influenza virus was found in fecal samples from "resident wild" mallards in Queen Anne's County in Maryland, on the U.S. central Atlantic coast.

"Testing has ruled out the possibility of this being the highly pathogenic H5N1 strain that has spread through birds in Asia, Europe and Africa," said USDA in a statement. "Test results thus far indicate this is low pathogenic avian influenza, which poses no risk to human health."


Five to 10 more days will be needed for definitive tests to confirm whether low-pathogenic H5N1 bird flu was found in the United States for the second time this year. On August 14, the virus was found in two mute swans in Michigan. Scientists say low pathogenic avian influenza commonly occurs in wild fowl.

The Maryland mallards did not appear sick so the samples, collected on August 2 as part of a research project, were not given high priority when sent to USDA labs for testing.

"The birds are alive and well," said a USDA spokeswoman.

The low-pathogenic strain of H5N1 has been found six other times in the United States since 1975. Mild and low pathogenic strains of bird flu are common in the United States and other countries.

The H5N1 bird flu strain has killed an estimated 141 people and forced hundreds of millions of birds to be destroyed, mostly in Asia. As a precaution, the U.S. government stepped up testing of wild birds for avian influenza in the continental United States this year.

http://today.reuters.com/news/articlenews.aspx?type=topNews&storyID=2006-09-01T214250Z_01_WAT006224_RTRUKOC_0_US-BIRDFLU-USA.xml&WTmodLoc=NewsHome-C1-topNews-3

[Harriet]

Re: U.S. finds low-risk H5N1 bird flu strain in ducks

Low path was found in poultry flock earlier this year; article from 5/1/06

Mild form of bird flu found in New Jersey...

NEW YORK (Reuters) - Authorities have discovered a mild form of avian influenza at a live bird market in New Jersey, but it is not the deadly H5N1 strain governments around the world are trying to contain, the state's agriculture department said.

"The strain was found in a live bird market in Camden County. None of the birds in the market died from this virus, which is an indicator that the virus was low pathogenic and not harmful to humans," said a statement by New Jersey's Agriculture Secretary Charles Kuperus which was posted on Friday.

Details were not immediately available on precisely when the avian flu in Camden County was discovered.

The H5N1 strain of avian influenza not only kills chickens quickly, but can now infect people, and governments around the world are scrambling to contain its spread. Scientists fear that if the virus acquires the ability to pass easily from person to person, it could cause a pandemic that would kill millions.


The H5N1 avian flu strain has already infected 205 people and killed 113 since 2003. Its spread has forced several countries to ban poultry imports from nations where the disease has spread.

The H5N1 virus has spread from Asia to Europe, the Middle East and Africa.

Kuperus said preliminary tests from the National Veterinary Services laboratory were negative for type N1 of the virus. More tests are pending at laboratories of the U.S. Agriculture Department in Ames, Iowa, to confirm the strain of the virus, he added.

"The market owner voluntarily depopulated his existing flock, and the market has undergone cleaning and disinfecting under New Jersey Department of Agriculture supervision," said Kuperus.

The market in Camden County will be inspected again by New Jersey's Division of Animal Health before being allowed to reopen.

[Harriet]

Tests rule out Asian bird flu in Michigan swans

Libby Quaid / Associated Press

WASHINGTON -- Bird flu found in a wild swan in Michigan was not the deadly Asian strain that has ravaged poultry and killed at least 141 people worldwide, the Agriculture Department said Monday.

Final tests confirmed the swan had a mostly harmless, low-pathogenic strain of the H5N1 virus, officials said.

Authorities found bird flu Aug. 14 in two mute swans on the shore of Lake Erie in Monroe County, Mich., but only one of the samples had high enough levels of flu to allow confirmatory tests. Earlier genetic analysis ruled out the more virulent Asian strain in both birds.

The low-grade strain has been found many times in North American wild birds and poses no threat to people, the department said. Confirmatory tests were done by the department's National Veterinary Services Laboratories in Ames, Iowa.

The swans were the first reported in the government's effort to test as many as 100,000 wild birds to determine if the virulent Asian H5N1 strain has arrived in North America. Officials expect the virus to reach the continent this year.

The sampling was expanded earlier this month from Alaska to the entire nation. Among the first targets were 20 mute swans from a game area in Monroe County. Testing found the possibility of H5N1 in two of the swans.

Any finding of highly pathogenic H5N1 in wild birds in the U.S. would prompt more intensive monitoring and extra security measures to protect commercial poultry flocks from infection.

Deadly, highly pathogenic strains spread rapidly and are usually fatal to chickens and turkeys, the department said, while low pathogenic H5N1 generally causes little sign of sickness in birds.

Since 2003, the virulent H5N1 strain has been blamed for the death or destruction of millions of birds overseas. Nearly all the people who have been infected had close contact with sick birds or their droppings. However, scientists fear the virus could mutate into a form that is spread easily among humans.

http://www.detnews.com[/B]

[Harriet]

Re: U.S. finds low-risk H5N1 bird flu strain in ducks

CONFIRMATORY TESTS BEING CONDUCTED ON MARYLAND WILD BIRD FECAL SAMPLES

WASHINGTON, Sept. 1, 2006-The U.S. Departments of Agriculture and Interior today announced that the presence of the H5N1 avian influenza subtype has been detected in fecal samples from wild birds in Maryland. Testing has ruled out the possibility of this being the highly pathogenic H5N1 strain that has spread through birds in Asia, Europe and Africa. Test results thus far indicate this is low pathogenic avian influenza (LPAI), which poses no threat to human health.

The fecal samples were collected on August 2 from resident wild ducks in Queen Anne's County, Maryland, as part of a research project conducted by Ohio State University. The fecal samples came from mallards that showed no signs of sickness, which also suggests that this is LPAI.


Because of the nature of the research project and because there was no sign of illness in the birds, the samples were not prioritized for testing. On August 24, 2006, USDA's National Veterinary Services Laboratories (NVSL) in Ames, Iowa received the samples. On August 31, 2006, NVSL tests indicated that nine samples were positive for the H5N1 avian influenza subtype. Today, genetic analysis of the virus was completed, which suggests that this virus is similar to low pathogenic strains that have been found previously in North America.


LPAI commonly occurs in wild birds, where it typically causes only minor symptoms or no noticeable symptoms. These strains of the virus are not a human health concern. This includes LPAI H5N1, commonly referred to as North American H5N1. This strain of LPAI is very different from the more severe HPAI H5N1 circulating overseas, which is commonly referred to as the Asian H5N1.


Additional testing at NVSL will confirm the pathogenicity of the virus. These results are expected within two weeks and will be made public when completed. It should be noted that wild birds are known to harbor many influenza viruses, and the finding of these viruses during routine testing is not unusual.

Recognizing that LPAI is endemic in wild bird populations, commercial poultry operators, including those in Maryland, employ extensive biosecurity measures to prevent exposure to wild birds and have done so for more than ten years. According to guidelines issued by the World Organization for Animal Health, known as OIE, there should be no trade restrictions imposed due to detection of avian influenza in wild birds.

Mallard ducks are among the wild bird populations that 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.


Numerous institutions of higher learning collaborate with USDA to conduct avian influenza testing. USDA issues grants to researchers, who voluntarily submit for testing the samples they collect from birds. This research-related testing compliments the extensive wild bird testing program implemented jointly by DOI and USDA in April 2006.


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

http://www.usda.gov/wps/portal/!ut/p/_s.7_0_A/7_0_1OB?contentidonly=true&contentid=2006/09/0335.xml

[Jeremy]

Re: U.S. finds low-risk H5N1 bird flu strain in ducks

I thought people might find this interesting.

http://www.who.int/entity/csr/diseas...N1-9reduit.pdf



From WHO's Avian Influenza Risk Assessment from January 2005

Page #17

Of greater concern, asymptomatic domestic ducks have recently been shown experimentally to excrete H5N1 in its highly pathogenic form, suggesting an important silent role in maintaining transmission. As these ducks can excrete large quantities of lethal virus without the warning signal of visible illness, it has become difficult to give rural residents realistic advice on how to avoid exposure. The role of domestic ducks may help to explain why several recent human cases could not be traced to contact with diseased poultry. It is also highly likely that apparently healthy ducks play a role in maintaining transmission by silently seeding outbreaks in other poultry.

What am I trying to say?


Nothing other than the real truth is that healthy ducks CAN excrete highly pathogenic H5N1. So just because the ducks were not dying doesn't mean anything. At least that is what WHO said in January 2005.

I am not saying that the ducks in Maryland are high path H5N1. I am just saying that the "the ducks weren't dying" is NOT good enough to rule out high path H5N1.

[HenryN]

Re: U.S. finds low-risk H5N1 bird flu strain in ducks

I thought people might find this interesting.

http://www.who.int/entity/csr/diseas...N1-9reduit.pdf


I am not saying that the ducks in Maryland are high path H5N1. I am just saying that the "the ducks weren't dying" is NOT good enough to rule out high path H5N1.

The US report indicated testing ruled out HPAI (as was also done in Michigan)

http://www.recombinomics.com/News/08..._Sequence.html

[Harriet]

Re: U.S. finds low-risk H5N1 bird flu strain in ducks

http://www.nwhc.usgs.gov/publications/field_manual/chapter_22.pdf

[Harriet]

AVIAN INFLUENZA Low Pathogenic H5N1 vs. Highly Pathogenic H5N1 Latest

AVIAN INFLUENZA Low Pathogenic H5N1 vs. Highly Pathogenic H5N1 Latest UPDATE September 1, 2006

There are two types of avian influenza (AI) that are identified as H5N1. A difference exists in the virus classification; one is low pathogenic (LPAI) and the other is highly pathogenic (HPAI). Pathogenicity refers to the ability of the virus to produce disease.

HPAI H5N1, often referred to as the "Asian" H5N1, is the type causing worldwide concern. LPAI H5N1, often referred to as the "North American" H5N1, is of less concern. Following is an explanation of the differences between them.

LPAI H5N1 ("North American" H5N1)

LPAI, or "low path" AI, commonly occurs in wild birds. In most cases, it causes minor sickness or no noticeable signs of disease. It is rarely fatal in birds. LPAI strains are not a human health concern. This includes LPAI H5N1.

Evidence of LPAI H5N1 has been found in wild birds in the United States in recent years and is not closely related to the more severe HPAI H5N1 circulating overseas. Examples of historical reports of LPAI H5N1 received by USDA include:

1975 ? LPAI H5N1 was detected in a wild mallard duck and a wild blue goose in Wisconsin as part of routine sampling, not as a result of noticeable illness in the birds

1981 and 1985 ? the University of Minnesota conducted a sampling procedure in which sentinel ducks were monitored in cages placed in the wild for a short period of time and LPAI H5N1 was detected in those ducks in both years.

1983 ? LPAI H5N1 was detected in ring-billed gulls in Pennsylvania.

1986 - LPAI H5N1 was detected in a wild mallard duck in Ohio as part of routine sampling, not as a result of noticeable illness in the birds.

2002 ? LPAI H5N1 antibodies were detected in turkeys in Michigan but the virus could not be isolated; therefore this detection could not be confirmed.

2005 LPAI H5N1 was detected in ducks in Manitoba, Canada.

2006 ? LPAI H5N1 was confirmed in two Michigan mute swans sampled as part of USDA's expanded avian influenza surveillance.

In the past, there was no requirement for reporting or tracking LPAI H5 or H7 detections in wild birds so states and universities tested wild bird samples independently of USDA. Because of this, the above list of previous detections might not be all inclusive of past LPAI H5N1 detections. However, the World Organization for Animal Health (OIE) recently changed its requirement of reporting detections of avian influenza. Effective in 2006, all confirmed LPAI H5 and H7 AI subtypes must be reported to the OIE because of their potential to mutate into highly pathogenic strains. Therefore, USDA now tracks these detections in wild birds, backyard flocks, commercial flocks and live bird markets.
HPAI H5N1 ("Asian" H5N1)

HPAI, or "high path" AI, spreads rapidly and is often fatal to chickens and turkeys. This includes HPAI H5N1. Millions of birds have died in countries where HPAI H5N1 has been detected. This virus has also infected people, most of whom have had direct contact with infected birds.

HPAI H5N1 has not been detected in the United States. However, other strains of HPAI have been detected and eradicated three times in the United States: in 1924, 1983 and 2004. No significant human illness resulted from these outbreaks.

The 1924 HPAI H7 outbreak was contained and eradicated in East Coast live bird markets.

The 1983-84 HPAI H5N2 outbreak resulted in humanely euthanizing approximately 17 million chickens, turkeys and guinea fowl in Pennsylvania and Virginia to contain and eradicate the disease.

In 2004, USDA confirmed an HPAI H5N2 outbreak in chickens in Texas. The disease was quickly eradicated thanks to close coordination and cooperation between USDA and State, local, and industry leaders.

TERMINOLOGY

Avian influenza (AI)--the bird flu--is a virus that infects wild birds (such as ducks, gulls, and shorebirds) and domestic poultry (such as chickens, turkeys, ducks, and geese). There is flu for birds just as there is for humans and, as with people, some forms of the flu in birds are worse than others.

AI viruses are classified by a combination of two groups of proteins: the hemagglutinin or H proteins, of which there are 16 (H1-H16), and neuraminidase or N proteins, of which there are 9 (N1-N9).

Pathogenicity: the ability of the virus to produce disease. AI strains also are divided into two groups based upon the ability of the virus to produce disease: low pathogenic (LP) and highly pathogenic (HP).

Low Pathogenic or "low path" avian influenza (LPAI): LPAI occurs naturally in wild birds and can spread to domestic birds. In most cases it causes no signs of infection or only minor symptoms in birds. These strains of the disease pose little significant threat to human health. These strains are common in the U.S. and around the world.

Highly Pathogenic or "high path" avian influenza (HPAI): HPAI is often fatal in chickens and turkeys. HPAI spreads rapidly and has a high death rate in birds than LPAI. HPAI has been detected and eradicated three times in U.S. domestic poultry. HPAI H5N1 is the subtype rapidly spreading in some parts of the world.

Last Modified: 09/01/2006

http://www.usda.gov/wps/portal/usdahome?contentidonly=true&contentid=2006/08/0296.xml

[Harriet]

Re: U.S. finds low-risk H5N1 bird flu strain in ducks

Also a poultry vet described it online:

Hi path vs. low path refers to how many birds are killed by the virus under test conditions. The Asian H5N1 is high path by that test (and the gene sequencing that has begun to complement the bird test), and the North American H5N1 is low path by the same criteria.

So high path and low path are usually different strains, but may be the same H and N types.

[Snowy Owl]

Re: U.S. finds low-risk H5N1 bird flu strain in ducks

Hi PoneyGirl,

Can you provide the link of that Vet quotation please.

Thank you

[Harriet]

Re: U.S. finds low-risk H5N1 bird flu strain in ducks

Just sent you mail.

[AlaskaDenise]

Re: U.S. finds low-risk H5N1 bird flu strain in ducks

LPAI can mutate to HPAI in 6 to 12 months. US says 6 to 9, but UK says up to 12 months.

From http://usinfo.state.gov/gi/img/asset...u_may_2004.pdf

<NOBR></NOBR>

...<NOBR>For example, during a 1999-2001 epidemic in Italy, an LPAI virus (H7N1) mutated into HPAI</NOBR>
HPAI in nine months. More than 13 million birds died or were destroyed.
<NOBR></NOBR>

.

[HenryN]

Re: U.S. finds low-risk H5N1 bird flu strain in ducks

LPAI can mutate to HPAI in 6 to 12 months. US says 6 to 9, but UK says up to 12 months.

From http://usinfo.state.gov/gi/img/asset...u_may_2004.pdf

<NOBR></NOBR>


.

The key to the "mutation" rate is the frequency of dual (or multiple) infections in the same host. The notes from Ohio State University show that dual infections in mallards are COMMON, and a dual infection is required for both reassortmant and recombination. See thread below for details

http://www.flutrackers.com/forum/showthread.php?t=9877

[HenryN]

Re: U.S. finds low-risk H5N1 bird flu strain in ducks

I thought people might find this interesting.

http://www.who.int/entity/csr/diseas...N1-9reduit.pdf




From WHO's Avian Influenza Risk Assessment from January 2005

Page #17

Of greater concern, asymptomatic domestic ducks have recently been shown experimentally to excrete H5N1 in its highly pathogenic form, suggesting an important silent role in maintaining transmission. As these ducks can excrete large quantities of lethal virus without the warning signal of visible illness, it has become difficult to give rural residents realistic advice on how to avoid exposure. The role of domestic ducks may help to explain why several recent human cases could not be traced to contact with diseased poultry. It is also highly likely that apparently healthy ducks play a role in maintaining transmission by silently seeding outbreaks in other poultry.

What am I trying to say?


Nothing other than the real truth is that healthy ducks CAN excrete highly pathogenic H5N1. So just because the ducks were not dying doesn't mean anything. At least that is what WHO said in January 2005.

I am not saying that the ducks in Maryland are high path H5N1. I am just saying that the "the ducks weren't dying" is NOT good enough to rule out high path H5N1.

You are correct on the pathology in waterfowl, although the Qinghai strain of H5N1 can kill waterfowl also (the WHO comments were based on experiments using Clade 1 H5N1 from Vietnam).

However, since the isolates in Michigan and Maryland were serotyped as H5N1, the possibility of a dual infection of HPAI and LPAI H5N1 is a real possibilty, which can be excluded by the size of the insert generated in the PCR test

http://www.recombinomics.com/News/06...5_PCR_PEI.html

[canagica]

Re: U.S. finds low-risk H5N1 bird flu strain in ducks

The key to the "mutation" rate is the frequency of dual (or multiple) infections in the same host. The notes from Ohio State University show that dual infections in mallards are COMMON, and a dual infection is required for both reassortmant and recombination. See thread below for details

http://www.flutrackers.com/forum/showthread.php?t=9877

After doing a quick check among the published literature, it wouldn't be quite accurate to state that they are "common", but rather that multiple infection (MI) rates vary widely across published reports.

For example, in a study done in 1998 in Maryland, of 209 wild ducks sampled, 29 had some form(s) of avian influenza (13.9%), and 18 of these were MI (a whopping 62%!).

http://www.bioone.org/archive/0005-2...47-s3-1107.pdf

In a different study, done in Alberta 1976-1990, 12321 wild ducks were sampled; 2839 had some form of AIV (23%), and 54 had MIs (a somewhat underwhelming 1.9%).

http://www.pubmedcentral.gov/picrend...3&blobtype=pdf

In Texas during 2001-2002, 258 wild ducks were sampled, 50 (19.3%) were AIV positive, and there were 7 MIs (14%).

http://www.uga.edu/scwds/documents/h...VinTXducks.pdf

1423 wild ducks were sampled from 1998-2000 in Minnesota; 154 (11%) were AIV positive and there were 15 MIs (10%).

http://www.bioone.org/archive/0005-2...-47-s3-867.pdf

I will be the first to admit that this bibliography is not exhaustive, but it does illustrate that a continuum of high-to-low coinfection rates exists and should be acknowledged.