Health officials have added two new foods to the list of products that have tested positive for bird flu.
Cottage cheese and sour cream, as well as one in five milk from the supermarket, have all tested positive for H5N1 particles in recent days.
But ground beef, infant formula and milk powder have all tested negative – a hopeful sign for mothers and meat lovers.
However, the FDA said the virus found in the products was “inactive” or dead, meaning it posed no risk of infecting people.
It comes as vets warn more people on farms are likely infected with the virus after hearing reports of sick workers on livestock farms recording outbreaks.
A check mark indicates foods that tested positive for avian flu, while a cross indicates which foods tested for avian flu but were not found to contain the virus
Dr. Barb Petersen, who works in the Texas Panhandle at the center of the outbreak, said nearly every farm with sick animals she visited also had sick people.
“It was just a surprise,” she said Fortune‘I was just a bit incredulous.
‘We were actively checking people out. I had people who never missed work, missed work.”
Her words echo those of other veterinarians, including one in Wisconsin — who said they had also heard reports of sick people on infected farms.
Only one person has tested positive for the virus this year: a farm worker who was in close contact with infected livestock. The CDC has tested 25 others, all of which were negative, and says about 100 people are under surveillance.
The map above shows states that have reported bird flu infections in cattle herds
The FDA did not disclose which brands of food it tested that were found to contain the bird flu virus.
But it did say the declaration was based on 297 dairy or cow products purchased from supermarkets in nine states that recorded outbreaks in livestock.
In a separate release, the USDA also revealed the results of testing 30 samples of ground beef — none of which were found to contain the virus.
It follows separate tests carried out on 96 milk samples from supermarkets last week, which showed one in five contained the virus.
Officials also conducted egg inoculation tests to determine whether the virus found in the food was still active and could infect humans.
This involves injecting a small amount of H5N1 particles from the products into a fertilized chicken egg, which is then monitored for changes that could indicate an infection, such as cell death.
But no changes were detected in the eggs in the experiments, which officials said showed that the products — even though they contained fragments of H5N1 — were still safe to eat.
The FDA says pasteurization — which involves rapidly heating and cooling milk to kill viruses — kills viruses and makes products safe for consumption.
Other foods such as butter, ice cream and pastries have not been tested for particles of the bird flu virus.
Dr. Donald Prater, acting director of the FDA’s Center for Food Safety and Applied Nutrition, said the virus was killed by pasteurization in all cases and therefore did not pose a health risk.
But some scientists have raised concerns about drinking milk that could contain fragments of bird flu, saying they still want to see more data.
Dr. Rick Bright, a virologist and former director of the Department of Health and Human Services who previously raised concerns about the presence of the virus in milk, said the initial data was “reassuring.”
‘Every new piece of data remains reassuring for pasteurized milk products.
‘(But) the data are preliminary and many critical experiments are still in preparation. And it’s all a snapshot. As the outbreak spreads to more businesses, more viruses may enter the system.”
So far, a total of 36 farms in nine states have reported bird flu among their livestock, with some experts expressing concern that the outbreak may be more widespread.
Cattle were reported to be lethargic and produce milk that was slightly off in color. The virus has been found in both their milk and lungs in previous cases.
Experts say farm workers can become infected with H5N1 if they come into close contact with livestock shedding the virus.