Initial tests have found probable avian influenza outbreaks at five new commercial poultry sites in Iowa, affecting more than 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 highly pathogenic H5N2 that is rapidly spreading, agency officials said. Positive results would push the outbreak's national tally to more than 15.1 million affected birds from commercial flocks in 13 states.
In the avian influenza outbreak of 1983 to 1984 in the northeast, which was the largest in U.S. history, about 17 million birds were culled.
"This is a big deal," Iowa Secretary of Agriculture Bill Northey said during a conference call on Monday. "Going forward, the question is are we done? Or does this mean more birds as we go forward."
Iowa state officials have quarantined the five farm sites, Northey said. Positive test results would mean that more than 9.5 million birds in Iowa have been affected by the virus.
Iowa farms, on average, house an estimated 60 million egg-laying hens, Northey said.
Also on Monday, the U.S. Department of Agriculture confirmed that a Wisconsin turkey farm with more than 1 million birds has tested positive for the virus. More than 1.9 million commercial production chickens and turkeys in Wisconsin have been affected by H5N2, state and federal officials have said.
The potential economic cost of the outbreak is unclear.
Hormel Foods Corp (HRL.N), based in Minnesota, said last week that avian influenza may drag its fiscal 2015 earnings toward the lower end of forecasts. More than two dozen of the poultry suppliers for Hormel's Jennie-O Turkey Store unit have been hit by the outbreak. Minnesota is the largest turkey-producing state in the country.
Last Tuesday, Mexico, the biggest buyer of U.S. chicken, halted imports of live birds and eggs from Iowa.
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.
Wisconsin and Minnesota have each declared a state of emergency over the outbreak.
Minnesota health officials said last week they were expediting prescriptions for antiviral drug Tamiflu for farm workers and others who have had direct contact with infected flocks. No human infections have been reported in this outbreak.
The virus has not been reported in the country's leading chicken meat producing states in the South, which include Georgia, Arkansas, Alabama, Mississippi and North Carolina.
The number of birds affected by the outbreak so far represents a fraction of the U.S. commercial flock. Chicken dominates U.S. poultry production. Poultry processors slaughtered nearly 8.7 billion chickens in 2014 and about 237 million turkeys, according Agriculture Department data.
IOWA HARD HIT
Iowa, the leading U.S. producer of table eggs, has been hardest hit in this outbreak, which was first identified in a backyard poultry flock in Oregon in December.
The Iowa Department of Agriculture and Land Stewardship said on Monday that initial positive tests for H5 avian influenza have been found in a commercial egg-laying farm with an estimated 1.7 million birds in Sioux County; a 250,000 egg-layer pullet farm in Osceola County; and in two commercial egg-laying operations in O'Brien County with a total of 338,000 birds.
Northey said a fifth farm, an egg-laying operation in Sioux County, with another 3.8 million chickens was identified on Monday as probably infected.
The five sites have been quarantined, state agriculture officials said. If the tests are confirmed, all birds on the properties will be euthanized.
Iowa 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 that facility houses 3.8 million hens.
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.