Pasteurization Inactivates Bird Flu Virus in Milk

A new study suggests that pasteurization kills the bird flu virus in milk as the outbreak in dairy cows expands in the United States.

About 200 animals and three people across 12 states have tested positive for highly pathogenic avian flu, or H5N1 bird flu, amid the ongoing outbreak. The virus was also detected in raw milk, raising concerns about the further spread in humans.

A new report published in the Journal of Virology suggests that pasteurization — the process of heating milk to a specific temperature to kill harmful bacteria — also inactivates the bird flu virus.

The investigators tested nearly 300 milk products from 132 processors and found no infectious virus in the samples.

“Milk is safe. Just like bacterial pathogens that occur in milk, or other viruses that could occur in milk, the sanitation processes that are in place are getting rid of the pathogens,” said Erica Spackman, Ph.D., a virologist in the U.S. Department of Agriculture and one of the study authors.

Bird flu primarily infects and spreads among migratory birds and can be transmitted to domestic poultry. Although the virus has been detected in other animals, including cats and dogs, the discovery of H5N1 on dairy farms in March was unexpected.

Soon after the discovery, diagnostic testing found an infectious form of the virus in raw milk, suggesting the virus passes from cow to milk.

The H5N1 bird flu risk for the general population in the U.S. remains low, according to the Centers for Disease Control and Prevention. All three infected individuals had direct contact with sick cows and experienced mild symptoms. None of the three cases are associated with the others.

Eggs can also pose bird flu risks

Eggs and poultry are another potential food source of the avian flu. To kill bacteria and viruses, they should be cooked to an internal temperature of 165°F (74°C).

You can also minimize the risks while handling eggs by taking the following steps:

  • Purchase eggs from reputable sources that follow strict biosecurity measures.
  • Store eggs in the refrigerator at 40°F (4°C) or colder immediately upon returning home.
  • Avoid using eggs that are cracked or dirty.
  • Always wash your hands, utensils, and surfaces with soap and water after they come into contact with raw eggs.
  • Cook eggs until both the white and yolk are firm.
  • When preparing poultry, wash hands and surfaces often, and separate raw meat from other foods.

Spackman said the new findings “give us reassurance that what we have been doing— pasteurization—is keeping us safe from what we don’t know about.”


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