Via CIDRAP, Robert Roos writes: USDA: H5N2 likely spreads by multiple routes. Excerpt:
The US Department of Agriculture's (USDA's) initial studies of how the H5N2 highly pathogenic avian influenza (HPAI) virus invades poultry farms point to no one clear factor but suggest that the explanation probably includes biosecurity gaps and possibly airborne transmission, the agency announced today.
The USDA's Animal and Plant Health Inspection Service (APHIS) "cannot . . . associate HPAI transmission with one factor or group of factors in a statistically significant way at this time, and will continue to update this report regularly as more analyses are completed," the agency said in a statement.
The USDA's first epidemiologic report on the H5N2 situation reiterates the agency's view that wild birds introduced H5N2 and H5N8 avian flu into commercial poultry originally, but says it is apparently spreading in other ways as well, given the number and proximity of farms affected.
"For instance, the report provides evidence that a certain cluster of farms was affected by identical viruses, pointing to possible transmission among those farms," the statement said. "In addition, genetic analyses of the HPAI viruses suggest that independent introductions as well as transmission between farms were occurring in several States concurrently."
The report says informal observations point to biosecurity lapses as a likely contributor to transmission. It also describes air sampling and wind studies that suggest a possible role for airborne spread of the virus.