The state with the most cases of highly pathogenic avian influenza (HPAI) in dairy cattle is taking another step to slow the spread. This week, Colorado’s Department of Agriculture announced a weekly bulk tank testing requirement for dairies in the state. This is the first statewide requirement issued in the country in response to the HPAI outbreak.

Effective Monday, July 22, all dairies licensed by the Colorado Department of Public Health and Environment (CDPHE) must submit a weekly bulk tank sample, and these samples must be collected by a CDPHE-certified sampler. They must be submitted to the Colorado State University Veterinary Diagnostic Laboratory.

Any dairy that has a non-negative result will be placed under quarantine, and all dairy producers must conform to the epidemiologic investigation requirements established by the state veterinarian.

The purpose of this testing, according to the statement released by the state’s Department of Agriculture, is to “survey for, identify, and isolate instances of highly pathogenic avian influenza in dairy herds to prevent further spread of the virus amongst dairy and poultry farms.” The order will remain in effect until further notice.

In the last 30 days, 30 herds in Colorado have had cows test positive for HPAI. Since the outbreak in dairy cattle began this spring, there have been 48 herds with positive test results in Colorado. Idaho is the second most-affected state, with 30 herds impacted during the outbreak. Michigan has had 26 infected herds, while Texas has had 22. Across the country, cows in 170 herds from 13 states have been impacted.