Federal officials say milk from dairy cows in Texas and Kansas has tested positive for bird flu.

Officials with the Texas Animal Health Commission confirmed the flu virus is the Type A H5N1 strain, known for decades to cause outbreaks in birds and occasionally infect people. The virus is affecting older dairy cows, causing decreased lactation and low appetite. The U.S. Department of Agriculture says the milk supply remains safe. Dairies are required to only allow milk from healthy animals to enter the food supply, and milk from sick animals is being diverted or destroyed. Pasteurization also kills viruses and other bacteria, and the process is required for milk sold through interstate commerce. Experts say livestock appear to recover on their own within seven to 10 days.