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.

Reports of H5N1 bird flu outbreaks at California dairy herds are continuing to rise as the nation’s largest milk producer scrambles to contain the spread. On Monday, officials reported that the number of infected dairy herds in the Central Valley had doubled over the weekend, rising from 17 to 34.

In the Central Valley, the state's Department of Food and Agriculture says 34 total dairy farms have had bird flu infections in their dairy herds

Why it matters: California now accounts for all but two of the nation’s recent H5N1 bird flu outbreaks in livestock over the past 30 days.

The mandatory testing comes as the total number of infected herds in California has risen to 17. Nationally, officials have announced 218 outbreaks across 18 states. In the last 30 days, however, California has accounted for all but two of the latest outbreaks.

With cases of highly pathogenic avian influenza in dairy cows rapidly rising in California, animal health officials continue to try to contain the spread, even as they remain flummoxed by

Faced with a surge in the number of California cows infected with H5N1 bird flu, state officials have quarantined 34 dairies and are urging other farms to take protective biosecurity measures.

Authorities are still investigating how the virus slipped in from outside the state, where 237 herds in 14 states are affected.

California's dairy industry grapples with a sudden surge in H5N1 bird flu cases, raising concerns about potential human transmission.