As bird flu virus concerns grow in US, so do tests of milk, cheese, meat and other foods

Public health officials have added cottage cheese, sour cream and baby formula to the list of items tested for bird flu after an outbreak among dairy cows.

Thirty-six cattle herds in nine states and one person in Texas tested positive for the H5N1 virus since late March. Federal officials have begun testing related food products after traces of the virus causing bird flu were found in pasteurized milk.

At a Wednesday news conference, representatives with the FDA, the CDC and the USDA reassured the public that the commercial food supply is likely safe, but reiterated that people should avoid drinking unpasteurized milk.

"As this situation evolves, the FDA will continue to consider all ongoing scientific research related to the effectiveness of pasteurization for HPAI in bovine milk," the FDA said in a related news release Wednesday. "We are also committed to continued surveillance of milk production, processing and pasteurization to help ensure the safety of the milk supply."

Experts weigh in: Four reasons to be concerned (but not freak out) about the bird flu

What is bird flu?

Bird flu is the non-scientific name for avian influenza, a type of flu virus that commonly infects waterfowl, turkeys and other birds. If it stays in birds, the main danger is to poultry. Flocks of chickens have had to be killed and eggs destroyed.

The larger concern is that it might evolve to become easily transmitted person-to-person. Bird flu is considered more dangerous than the annual flu because it's a strain humans have never encountered before and it's likely to be highly contagious.

This probably hasn't happened yet, experts say.

Sour cream and cottage cheese also had bird flu particles

The FDA announced it has tested a total of 297 commercial samples of milk products with evidence of the virus, including fluid milk, cottage cheese and sour cream.

In all cases, the virus had been killed by pasteurization and so posed no health risk, said Dr. Donald A. Prater, the FDA's acting director of the Center for Food Safety and Applied Nutrition.

FDA says infant and toddler formula free of viral particles

The agency also tested infant and toddler formula and found no viral particles at all, Prater told reporters.

"To ensure the safety of milk-derived products for our youngest populations, the FDA also tested samples of retail powdered infant formula and powdered milk products marketed as toddler formula," they said.

The FDA is also in the process of identifying additional products to be tested.

FDA also testing ground beef, but 'confident' it is safe

Federal officials already announced they would begin testing ground beef from stores in states with outbreaks of bird flu in dairy cows.

While there is no known case of bird flu virus being found in ground beef, samples will be analyzed by the Animal and Plant Health Inspection Service using tests that detect "whether any viral particles are present," the agency said.

Two other safety studies will be conducted, as well, because some dairy cows are processed into ground beef when they grow old. The Food Safety and Inspection Service will collect muscle samples from dairy cattle being at slaughter facilities, and those samples will also undergo tests.

The agency will do additional testing for live virus on any positive tests from muscle samples and retail ground beef, and do cooking studies of ground beef to determine what temperatures are needed to kill the virus, the USDA says.

Food safety tips: avoid unpasteurized products, undercooked meat and fish

Here is what experts say to keep in mind about food safety amid the bird flu outbreak:

Contributing: Mary Walrath-Holdridge, Emily DeLetter, Jeanine Santucci

This article originally appeared on USA TODAY: As bird flu virus concerns grow, this is how US is testing food supply