Health officials said the first "severe" case of the H5N1 virus was reported in a human this week, with the person being hospitalized.

Health authorities have stressed that pasteurized milk is safe to drink. But officials are worried about the risks of raw milk — especially in California, where two raw milk producers have recalled their products after bird flu was detected in retail samples.

The public health risk for the bird flu is very low, but researchers are keeping a close eye on how it spreads.