US to test fewer wild birds for avian flu this year

Editor's note: This story was revised May 8 to include a piece of additional information on testing of environmental samples.

May 7, 2007 (CIDRAP News) – US government agencies said today they will test fewer wild birds for the H5N1 avian influenza virus in the 2007 season than they did last season, while focusing on the highest-risk species and locations.

The two agencies that monitor wild birds—the US Department of Agriculture (USDA) and the Department of the Interior (DOI)—collected about 109,000 samples from birds during the 2006 season, which ran from Apr 1, 2006, to Mar 31, 2007, said Karen Eggert, a spokeswoman for the USDA's Animal and Plant Health Inspection Service (APHIS).

The two agencies plan to collect about 77,000 bird samples for the 2007 season, about 32,000 fewer than in 2006, Eggert told CIDRAP News. She said the agencies also plan to test 25,000 fecal environmental samples, down from 50,000 tested last season.

Based on information collected last season, the USDA's strategy for this year will focus on sick and dead birds from duck species believed to be the most likely carriers of H5N1: mallards, American wigeons, and northern pintails, Eggert said.

The agencies will focus on the Pacific, Atlantic, Central, and Mississippi flyways, as well as Hawaii in the South Pacific, she said.

The largest number of samples will be taken from birds in Alaska, according to a Reuters report today. US monitoring efforts began in Alaska in the summer of 2005. Alaska is at the forefront of wild bird monitoring because it is the first US stopover for birds from Asia and other continents where the H5N1 virus is present.

In August 2006, the USDA and DOI broadly expanded wild-bird monitoring for H5N1 beyond Alaska to the lower 48 states, Hawaii, and other Pacific islands. According to the Highly Pathogenic Avian Influenza Early Detection Data System (HEDDS), testing found no cases of highly pathogenic H5N1 and only isolated cases of low-pathogenic H5N1 and H5N3 strains of avian flu in six states (Delaware, Illinois, Maryland, Michigan, Montana, and Pennsylvania), common findings in North American birds.

Other possible routes of H5N1 introduction into the United States include the importation of infected poultry or pet birds that could spread the disease to wild birds along US flyways.

Meanwhile, animal health officials in Vietnam said the H5N1 virus has probably resurfaced in ducks in the country's central province of Nghe An, the Chinese news service Xinhua news reported today.

Samples from the ducks were positive for an H5 virus, and further tests are being conducted to determine if it is the deadly H5N1 strain, Thanh Nien News, a Vietnamese newspaper, reported yesterday.

Officials said 246 of 610 ducks in the affected flock died between May 1 and 4, Xinhua reported. The flock had not been vaccinated to prevent bird flu, and the remaining ducks were culled, according to Thanh Nien News.

Vietnam's last poultry deaths from H5N1 were reported in January 2007, according to the World Organization for Animal Health (OIE). According to the World Health Organization, Vietnam has had 93 human H5N1 cases and 42 deaths, but there have been no new reports since November 2005.

In other avian flu news, officials in Bangladesh detected avian flu at another chicken farm, which led to the culling of 1,500 chickens at the farm near Rajason on May 3, The Daily Star, a Bangladeshi newspaper, reported yesterday. As a precaution, officials culled 8,500 more birds the next day on three nearby farms in Savar, about 15 miles northwest of Dhaka, the capital, the story said.

Bangladesh reported its first H5N1 outbreak in poultry in late March. Figures from the latest report and previous ones indicate that more than 80,000 birds have been culled so far.

In France today, agriculture officials lowered the country's avian flu risk level to "negligible." The risk had been raised to "weak" in February after avian flu was detected on a British turkey farm, Reuters reported.

The British outbreak, at a farm in Suffolk, led to the culling of 160,000 turkeys, Reuters reported. A final epidemiological report released by the UK Apr 19 said the source of the virus remained unknown but might have been contaminated turkey meat imported from Hungary

The H5N1 virus has not been detected in France since April 2006, according to reports posted on the OIE Web site. H5N1 infections had previously been detected in wild birds and at a turkey farm.

See also:

CIDRAP avian influenza overview

OIE reports on Vietnamese poultry outbreaks
http://www.oie.int/downld/AVIAN%20INFLUENZA/A2007_AI.php

OIE report on French H5N1 outbreaks
http://web.oie.int/wahis/reports/en_imm_0000005696_20070705_173643.pdf

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