An outbreak of avian flu in Tennessee has health officials on alert as the virus has surged across parts of Asia in recent months.
The Tennessee Department of Agriculture confirmed yesterday that approximately 74,000 chickens from a commercial farm in Lincoln County were culled after some of the animals tested positive for a strain of the highly pathogenic avian influenza (HPAI).
Today, Tennessee government officials said the strain of the virus found in Tennessee is a North American strain, which they don't believe is connected to the avian influenza A(H7N9) strain in Asia that has caused serious illness in humans.
Between 2013 and 2017, a total of 1,258 avian influenza A(H7N9) virus infections in China were reported to the World Health Organization (WHO), with 41 percent of the cases resulting in fatalities.
The virus found in Tennessee has been identified as an H7 virus, most likely spread from wild birds in North America. The Tennessee Department of Agriculture said it is assessing the exact strain of the virus. The department reiterated that they believed there is little to no risk to humans or the food supply as a result of this outbreak.
"This is a virus of birds, wild birds, not humans, we don't recognize a lot of risk," said John Dunn deputy state epidemiologist at a press conference today. He added that responders and personnel on the farm are under surveillance in case they do develop flu-like symptoms.
Of the eight buildings where the chickens were located, infected birds were found in only one. Tennessee State Veterinarian Charles Hatcher said all the chickens that has been housed in the area were culled and buried within 24 hours to quickly minimize exposure to the virus.
"If you leave this high-powered virus around, nothing but bad things can happen," Hatcher said at the press conference.
Bird flu rarely infects people unless they are in extremely close proximity to poultry and the virus does not spread easily or at all from person to person.
Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, who consulted with the Tennessee Department of Health, agreed that the virus is unlikely to spread widely among people in the U.S. due to the nature of the virus and the fact that people rarely interact with live poultry.
People who live extremely close to poultry as they do in parts of China, Schaffner added, are at increased risk for large exposure to the virus.
"You can inhale it and when that virus gets deep down into your lungs it can find receptor sites that it can get into the cells and cause inflammation, pneumonia," said Schaffner. "Because it's deep down, it's not readily transmitted from person to person."
Schaffner said the fear among public health officials is that a strain of the avian influenza could mutate so that it could infect people more easily, via the upper airways or nasal passage. In that scenario, the virus would likely spread more easily from person to person via cough or sneeze, similar to the seasonal flu.
But the risk of that worst-case scenario is low.
"Fortunately, picking up that genetic material happens very rarely," said Schaffner.
The Tennessee Department of Agriculture has not yet determined the cause of the outbreak. One possibility is that the virus could have spread among wild birds that migrated through the area and infected the poultry, Schaffner said.
The chicken farm where the virus was found remains under quarantine, as well as all farms in a 10 mile area are under quarantine, according to the Tennessee Department of Agriculture.