By P.J. Huffstutter
CHICAGO (Reuters) - Initial tests have found five probable new cases of the rapidly spreading avian influenza on commercial poultry sites in Iowa, affecting an estimated 6 million birds, the state's agriculture department and the U.S. Department of Agriculture said on Monday.
Additional tests are pending to confirm the presence of the highly pathogenic H5N2, agency officials said. If these tests are positive, the state's tally of egg-laying chickens affected by the virus and needing to be culled would be more than 9.5 million birds, Iowa Secretary of Agriculture Bill Northey said on a conference call on Monday.
Iowa farms house, on average, an estimated 60 million egg-laying hens, Northey said.
"This is a big deal," Northey said. "Going forward, the question is are we done? Or does this mean more birds as we go forward."
Initial positive tests for H5 avian influenza were found in a commercial egg-laying farm with an estimated 1.7 million birds in Sioux County; a 250,000 pullet farm in Osceola County; and in two commercial egg-laying operations in O'Brien County with a total of 338,000 birds, the Iowa Department of Agriculture and Land Stewardship said.
Northey said a fifth egg-laying farm in Sioux County with another 3.7 million chickens was identified on Monday as probably infected with the virus.
The five sites have been quarantined, state agriculture officials said. If the preliminary tests are confirmed, all birds on the properties will be euthanized.
Iowa, the top U.S. egg-producing state, said last week that a lethal strain of bird flu had been found in hens at an egg-laying facility near the city of Harris run by Sunrise Farms, an affiliate of Sonstegard Foods Company. The company said the facility houses 3.8 million hens.
Two bird flu strains have been discovered in the United States this year. The H5N2 strain is in Arkansas, Idaho, Iowa, Kansas, Minnesota, Missouri, Montana, North Dakota, Oregon, South Dakota, Washington and Wisconsin. It has also been identified on farms in Ontario, Canada.
The H5N8 strain has been identified in California and also in Idaho, U.S. Department of Agriculture data showed.
The virus can kill nearly an entire infected flock within 48 hours. Millions of turkeys and chickens are in quarantine waiting to be culled and large flocks have already been destroyed.
Officials have said they believe wild birds are spreading the virus but they do not know how it is entering barns.
(This version of the story updates number of cases and adds comments from state agriculture secretary)
(Reporting By P.J. Huffstutter; Editing by Toni Reinhold)