ARS TECHNICA – Researchers around the world are growing more uneasy with the spread of highly pathogenic avian influenza (H5N1) in US dairy cows as the virus continues to make its way into new herds and states.
Several experts say the US is not sharing enough information from the federal investigation into the unexpected and growing outbreak, including genetic information from isolated viruses.
To date, the US Department of Agriculture has tallied 32 affected herds in eight states:
Idaho, Kansas, Michigan, New Mexico, North Carolina, Ohio, South Dakota, and Texas.
Early infections in Texas were linked to dead wild birds (pigeons, blackbirds, and grackles) found on dairy farms. But the USDA reportedly indicated to Stat News that the infections do not appear to be all linked to the Texas cases.
Spread of the virus via cattle movements indicates that there is cow-to-cow transmission occurring, the USDA said. But it’s unclear how the virus is spreading between cows.
Given that even the most symptomatic cows show few respiratory symptoms, the USDA speculates that the most likely way it is spreading is via contaminated milking equipment.
Adding to the uncertainty of the virus’s spread, The New York Times on Friday reported that the one herd found infected with H5N1 in North Carolina showed no symptoms of the virus.
This raises the possibility that the virus could be silently spreading in unknown numbers of other asymptomatic herds and states. In its most recent FAQ document, the USDA encouraged testing for H5N1 if herds show clinical symptoms, such as lethargy, fever, low milk production, and loose stools.
But the Times noted that the agency has begun reimbursing farms for testing asymptomatic cows …
On Sunday, facing mounting criticism, the USDA announced the release of 239 genetic sequences to GISAID. It noted it is also adding raw data to a US federal database “in the interest of public transparency …”
BETH MOLE is Ars Technica’s Senior Health Reporter. Beth has a Ph.D. in microbiology from the University of North Carolina at Chapel Hill and attended the Science Communication program at the University of California, Santa Cruz. She specializes in covering infectious diseases, public health, and microbes.
