Bird flu is spreading rapidly in California; infected herds double over weekend

The H5N1 bird flu appears to be stampeding through dairy farms in California, the country's largest milk producer. Over the weekend, the total number of confirmed infected cow herds stunningly doubled, going from 17 last Thursday to 34 Monday morning, according to state and federal officials.

With the new tally, California now ranks second among all affected states for having the most herds with avian influenza. Only Colorado, which has adopted bulk milk-tank surveillance, has more, with 64 herds confirmed. California's high ranking is despite the fact that it only reported its first three infected herds on August 30, while the dairy outbreak was first confirmed on March 25 and thought to have begun late last year.

To date, 232 herds in 14 states have been infected with the bird flu.