Sales of raw milk appear to be on the rise, despite an outbreak of bird flu in U.S. dairy cows. Federal officials warn about the health risks of drinking raw milk at any time, but especially during the outbreak.

Sales of raw milk appear to be on the rise, despite years of warnings about the health risks of drinking the unpasteurized products — and an outbreak of bird flu in dairy cows.

Since March 25, when the bird flu virus was confirmed in U.S. cattle for the first time, weekly sales of raw cow’s milk have ticked up 21% to as much as 65% compared with the same periods a year ago, according to the market research firm NielsenIQ.

That runs counter to advice from the Food and Drug Administration and the Centers for Disease Control and Prevention, which calls raw milk one of the “riskiest” foods people can consume.

“Raw milk can be contaminated with harmful germs that can make you very sick,” the CDC says on its website.

As of Monday, at least 42 herds in nine states are known to have cows infected with the virus known as type A H5N1, federal officials said.

The virus has been found in high levels in the raw milk of infected cows. Viral remnants have been found in samples of milk sold in grocery stores, but the FDA said those products are safe to consume because pasteurization has been confirmed to kill the virus.