Avian flu

by Cat Urbigkit

State and federal animal health officials will sample various bird species throughout the state beginning next month in an aggressive disease surveillance effort.

On Tuesday morning, the Wyoming Game and Fish Department hosted an interagency press conference on avian influenza, a widely endemic (present in low levels at all times) viral infection in wild populations of waterfowl and many other species of birds. The emergence and spread of a highly pathogenic avian influenza H5N1 subtype in Asia, Europe and Africa in recent years has elevated concerns about potential expansion of this virus to North America. To date, the H5N1 strain of avian influenza has not been detected in North America.

Assistant State Veterinarian Dr. Walt Cook explained that there are 144 strains of the virus. While the low pathogenic strains cause mild symptoms of disease and does not cause the death of birds, highly pathogenic strains are rare, involve the H7 or H5 protein and cause a 75-100 percent mortality rate in domestic poultry.

Wyoming is to be unlikely to be the first state to detect H5N1 in North America, Cook said, although other strains could be detected, as was a recent outbreak of the H5N2 strain in Texas in 2004.

H5N1 could arrive in North America in several manners, Cook explained. A low pathogenic strain could mutate; through human importation of domestic fowl; or natural migration of wild birds. The most probable method for the strain to arrive in the United States is through illegal importation of poultry.

Dr. Jamie Snow, the state public health veterinarian for the Wyoming Department of Health, said there is no public health risk to the citizens of Wyoming at this time since it’s not in North America and because itis primarily a bird disease. A pandemic is only possible if the virus changes to allow human-to-human transmission.

As of mid–April 2006, H5N1 has caused illness in 204 people and the death of at least 113 people, mostly in Cambodia, China, Indonesia, Thailand, VietNam and Turkey. These victims had extensive exposure to infected chickens, ducks, turkeys, their environment or raw poultry parts. To date, there has been no sustained person–to–person transmission of H5N1.

Most of the people infected with H5N1 virus have acquired it through direct handling of infected poultry, eating uncooked or undercooked poultry products or through contact with virus–contaminated surfaces or materials, including blood and feces.

USDA Animal and Plant Health Inspection Service State Director Rod Kriscke said his agency’s role is to obtain samples from wildbirds in Wyoming. Kirschke explained that starting this summer, live birds will be captured and sampled for avian influenza. After the birds are examined and cloacal swabs are taken, the birds will be released. Environmental samples (fresh feces) and samples from dead birds collected from morbidity/mortality events and hunter check stations will supplement the live bird samples.

Wyoming is not a main migratory route for waterfowl and shorebirds in North America.

Birds migrating through this part of the Central and Pacific flyways are considered to be at the lowest level of risk for acquiring H5N1 infection.

The primary candidate species for H5N1 surveillance in the Central Flyway are the sandhill crane, tundra swan, Northern pintail, buff-breasted sandpiper, long-billed dowitcher and the pectoral sandpiper. The secondary species include Canada goose and several other goose species, numerous duck species, several species of sandpipers, plovers, yellow-legs andgulls.

Although the risk is low that H5N1 will be introduced in Wyoming in the near future, according to Cook, surveillance by the Wyoming Livestock Board and State Veterinarian's office will focus on testing show and display foul and on animals within the game bird industry.

Cook noted that under existing law in Wyoming, all animals entering the state require health importation papers. This documentation entails an exam from a licensed veterinarian within 30 days of shipment. It is the policy of the Wyoming Livestock Board not to allow birds from areas with AI into the state.