A new strain of avian influenza was discovered earlier this week when a number of commercial turkey farms in the Dubois County, Indiana, the largest turkey producing county in the state, tested positive for the virus. However, recent reports have found that the outbreak occurred from a new strain of the virus, known as H7N8, which is a new, low-pathogenic stain compared to H5N2. An outbreak of H5N2 resulted in the depopulation of 7.5 million turkeys and 42.1 million egg-layer and pullet chickens in June 2015.
“These new cases were identified as part of surveillance testing in the control area surrounding the initial highly pathogenic avian influenza case. Testing is currently ongoing at the National Veterinary Services Laboratories in Ames, Iowa to determine the pathogenicity of these new cases,” the USDA said in a recent article.
As a precaution, however, approximately 413,000 birds from the area have been euthanized including a large number of chickens, who were not infected, but were considered to be in “dangerous contact” with an infected turkey flock.
The USDA added that it appears the low-pathogenic strain of H7N8 has been circulating among flocks and had somehow mutated into a highly pathogenic form that affected the first farm. This raised alarm bells immediately as the highly pathogenic virus can quickly sweep through turkey and chicken flocks, killing them in days or hours.
This was seen in the outbreak that occurred last spring in which a total of 211 commercial and 21 backyard poultry premises were infected, leading to devastating effects on the poultry businesses, driving up egg costs specifically and costing federal taxpayers more than $950 million.
While everything appears to be back to normal now, the surveillance in the recent outbreak in Indiana will continue for at least 21 days after the last positive test for the virus is reported. If no new cases show up in this time period, this outbreak will be declared over.
Infected birds pass on the avian influenza virus through their saliva, nasal secretions and feces with migratory birds able to serve as carriers of the virus while never actually contracting it. The possibility of a pandemic spreading among domestic birds and into the human population worldwide has been a major concern in the U.S.
To date, there is no commercially available vaccine to protect humans from the virus, therefore, putting a priority on biosecurity and sanitizing programs that can help prevent the virus’ spread. In September of 2015, the HPAI Preparedness and Response Plan was released by the USDA and provides a plan for preventing and responding to highly pathogenic avian influenza (HPAI) cases.
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