Avian flu gone in Texas but persists in Canada

Apr 1, 2004 (CIDRAP News) – Texas officials announced today that the state's outbreak of highly pathogenic avian influenza (AI) has been eradicated, after 352 noncommercial poultry flocks in the area were found to be free of the disease.

Meanwhile, a battle with a different strain of AI in southern British Columbia continued, as Canadian officials said yesterday they had confirmed the disease on a seventh farm in the Fraser Valley east of Vancouver.

Texas outbreak confined to one farm
The Texas Animal Health Commission (TAHC) announced the eradication of the outbreak of H5N2 AI near Gonzales, about 60 miles east of San Antonio. The outbreak never spread beyond the farm where it was first discovered in mid-February, the commission said. Officials said commercial flocks as well as the 352 noncommercial flocks in the area all tested negative for the virus.

"Laboratory test results, epidemiological reports, and good veterinary science provide assurance that this Texas AI infection has been wiped out," said Dr. Max Coats, the TAHC deputy director of animal health programs. "We still are working to determine how the infection may have been introduced into the flock."

The infected flock of 6,600 broiler chickens was destroyed Feb 21, and the site was thoroughly cleaned and disinfected afterward, the TAHC said. In addition, five live-bird markets in Houston, including two that had received birds from the affected farm, were "depopulated" and cleaned.

A 50-member task force of TAHC and US Department of Agriculture (USDA) veterinarians and inspectors combed the Gonzales area for 5 weeks to find and test noncommercial flocks, the TAHC said.

"Since late February, the TAHC and USDA task force team has tested and retested noncommercial flocks as many as four times within a 10-mile radius around the premise where the infected chickens were housed," Coats said. The task force followed strict biosecurity guidelines to avoid spreading any disease from one farm to another, he noted.

Investigators also sampled noncommercial flocks near commercial farms in a zone from 10 to 30 miles from the infection site, and all were disease-free, Coats said. Meanwhile, routine testing of commercial flocks in the area was increased, he said.

Coats said Texas still faces the task of persuading nearly 40 countries to lift import bans on the state's poultry products.

Canadian officials confirm seventh outbreak site
In British Columbia, the presence of AI on a seventh farm was confirmed yesterday by the Canadian Food Inspection Agency (CFIA). The agency didn't specify the viral strain, but previous statements about the outbreak have listed the virus as H7N3.

The CFIA did not make clear how far the farm was from the other infected sites; a Canadian Press report said it was outside a 5-kilometer-wide "high-risk" zone but within a larger control area.

A CFIA statement said, "The Agency has now confirmed avian influenza on seven commercial farms—six within the high-risk region and one in the broader control area." The agency also said it had quarantined another farm in the control area on the basis of preliminary test results and was conducting confirmatory tests.

Besides the commercial flocks, three small noncommercial flocks have been found to have AI, the CFIA said. Those flocks have been destroyed, officials said.

The seventh infected commercial flock was quarantined Mar 29 on the basis of preliminary tests, according to the CFIA. At that point the agency said there was also evidence of a mild strain of Newcastle disease in the flock. But yesterday's announcement about AI in the flock didn't mention Newcastle disease.

Officials first confirmed the presence of AI in British Columbia on Feb 19. Recent reports have said that 365,000 chickens and turkeys were targeted for destruction in the control effort.

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