Animal health officials in Tennessee yesterday announced that a second H7N9 avian flu outbreak has been detected at a farm in Giles County in the southern part of the state, but tests show the virus is low pathogenic, not the highly pathogenic strain found recently in neighboring Lincoln County.
The Giles County farm is a poultry breeding operation owned by a different company than the one associated with the Lincoln County outbreak, and for now investigators don't believe one farm affected the other, the Tennessee Department of Agriculture (TDA) said in a statement.
Routine screening identified avian influenza in the flock on Mar 6, and tests at state and federal labs confirmed low-pathogenic H7N9 in the samples. In a video statement, Charles Hatcher, DVM, Tennessee's state veterinarian, said operators at the Giles County farm noticed a slight increase in mortality and a slight decrease in egg production.
He said out of an abundance of caution authorities culled the flock, and the birds have been buried. A 10-kilometer surveillance zone was placed around the facility, and Hatcher said there is only one commercial farm in the zone, which has so far tested negative for avian flu.
The Giles County farm housed 16,500 chickens, according to a report on the outbreak today from the World Organization for Animal Health (OIE).
Tennessee officials reiterated that genetic tests on a virus isolated from the Lincoln County outbreak revealed that all gene segments are from North American wild bird lineages, with no connection to the H7N9 circulating in China and causing cases in people.
Human risk low
In a related development, the US Centers for Disease Control and Prevention (CDC) on Mar 8 said it is working with federal and state officials to minimize any human health risks posed by the outbreak developments. The protocol involves monitoring the health of poultry workers who were exposed to the outbreak farm flocks.
So far no human illnesses have been detected, the CDC said. Though the public health risk is low, the CDC added that there have been a small number of human infections reported in North America from avian H7 viruses. Most were linked to poultry exposure, with patients showing mild respiratory symptoms, sometimes with conjunctivitis.
The Lincoln County event is the first highly pathogenic avian flu outbreak in the United States this year. The Giles County outbreak is the second outbreak of the year to involve a low-pathogenic strain; earlier this week federal health officials said H5N2 was found in an outbreak involving a commercial turkey farm in Barron County, Wis.
Mar 9 TDA statement
Mar 9 TDA video
Mar 10 OIE report
Mar 8 CDC statement
Mar 7 CIDRAP News story "North American-origin H7N9 isolated from Tennessee farm"