The CDC has issued an urgent warning against drinking raw milk as a major bird flu outbreak spreads across dairy cattle in the US.

As of Monday, federal officials said at least 42 herds in nine states are known to have cows infected with the type A H5N1 virus. There haven’t been any human cases since last month in Texas.

The virus has been found in high levels in the raw milk of infected cows, and viral remnants have been found in samples of milk sold in grocery stores, the Food and Drug Administration (FDA) said.


However, the FDA said those products are safe to consume because pasteurization has been confirmed to kill the virus. And consumers don’t seem to mind, as weekly sales of raw cow’s milk ticked up 21 percent to as much as 65 percent compared with the same period a year ago.

That is contrary to the CDC’s advice, which calls raw milk one of the “riskiest” foods people can consume.

The CDC wrote on its website: “Raw milk can be contaminated with harmful germs that can make you very sick.”

The CDC also warned last week that people who drink raw milk could theoretically become infected if the bird flu virus comes in contact with receptors in the nose, mouth, and throat or if they inhale the virus into the lungs.

There’s also concern that if more people are exposed to the virus, it could mutate to spread more easily in people.

States have widely varying regulations regarding raw milk, with some allowing retail sales in stores and others allowing sales only at farms. Some states allow so-called cowshares, where people pay for milk from designated animals, and some allow consumption only by farm owners, employees, or “non-paying guests.”

Research shows that raw milk is far more likely than pasteurized milk to cause illnesses and hospitalizations linked to dangerous bacteria such as campylobacter, listeria, salmonella, and E. coli.

According to the CDC, there were more than 200 illness outbreaks traced to raw milk between 1998 and 2018, infecting more than 2,600 people and hospitalizing more than 225.

Despite the general risks of raw milk, about 4.4 percent of US adults – nearly 11 million people – report that they drink raw milk at least once a year, and about 1 percent said they consume it each week, according to the FDA.