No bird flu virus was found after cooking ground beef to medium to well done, the U.S. Department of Agriculture said on Thursday after conducting a study as it addresses concerns over an outbreak of the disease in dairy cattle.
The findings indicate that properly cooking hamburgers to a temperature of about 145 to 160 degrees Fahrenheit (63 to 71 degrees Celsius) keeps them safe for consumers.
The agriculture department (USDA) previously said 30 samples of ground beef from retail outlets tested negative for H5N1 virus and that the U.S. meat supply is safe.
The cooking experiments were done after a surrogate of the H5N1 virus was added to the beef.
Hamburgers cooked to 120 degrees F showed the virus surrogate was present at reduced levels, the USDA said.
The U.S. has confirmed bird flu in dairy cattle in nine states since late March. Older dairy cattle are often processed into ground beef.
Scientists have said they believe the outbreak is more widespread based on U.S. Food and Drug Administration findings of H5N1 particles in about 20% of retail milk samples. The FDA has said tests of retail dairy samples were negative for viable H5N1 bird flu virus but cautioned against consuming raw unpasteurized milk.
One dairy farm worker in Texas tested positive for the virus in the current outbreak and reported conjunctivitis. The U.S. Centers for Disease Control and Prevention has said the risk to the general public is low.
