California health officials are warning not to drink another lot of raw milk from Fresno-based Raw Farm after it tested positive for bird flu virus. More testing of Raw Farm products is underway, the state said.

California health officials announced Wednesday that another batch of raw milk from Fresno-based Raw Farm has tested positive for bird flu virus, as dairy farms throughout the state continue to struggle with a widening number of outbreaks.

Pasteurization is the process that rids milk of bacteria. But more people are opting for unpasteurized milk, also known as raw milk. In May, sales of raw milk rose more than 20 percent compared to the year before.