HPAI federal order considering bulk tank testing

MADISON, Wis. — For over eight months the dairy industry, agriculture and public health officials have been trying to stop the spread of HPAI H5N1, while gaining little understanding of how the disease is spreading among dairy cows.

“Surveillance is key for dairy farmers, especially for what is happening right now with the flu,” said Dr. Keith Poulsen, director of the Wisconsin Veterinary Diagnostic Laboratory.

Poulsen expects the U.S. Department of Agriculture will soon implement an enhanced testing policy to increase surveillance of the disease in an effort to stem the continued spread.

As of Dec. 4, 707 dairy farms in 15 states have been confirmed to have cases, 493 of which have occurred in California, which has added 263 cases in the past 30 days.

In response, the USDA announced plans for a new federal order aimed at increased surveillance testing in late October, but has yet to come forth with details on specific guidance.

In a press release, the USDA referenced past successes, including the eradication of brucellosis in dairy herds, by using bulk milk testing to surveil.

According to the initial press release, plans are to begin sampling milk in bulk at the regional level, moving towards farm-level testing if necessary, until an area is determined to be free of the virus.

According to Poulsen, bulk tank polymerase chain reaction testing is capable of detecting minute levels of virus in tankers and silos full of milk, making successful surveillance at that level a reasonable expectation.

Protecting the dairy industry, a primary economic driver in Wisconsin, is Poulsen’s primary motivation in his crusade to eliminate the virus. He noted the constant movement of dairy cattle throughout the U.S. makes national surveillance imperative.

“The American Veterinary Medical Association and the American Association of Bovine Practitioners agree this is a national consensus issue, that in order to eliminate this virus we need to start with better surveillance,” Poulsen said. “We can’t have 50 different states with 50 different surveillance programs.”

Several states including Colorado, Idaho and California have put bulk tank testing in place since H5N1 was first diagnosed in March.

According to Poulsen, science underlines the value of surveillance testing, citing how an Idaho herd was able to tailor their response to the disease striking their herd before cows began showing clinical signs.

Poulsen explained that affected cows shed the virus well in advance of experiencing clinical symptoms. When the virus was first found in Idaho, Poulsen said one herd began surveilling their herd using daily bulk tank PCR testing. The test located virus RNA in the milk more than two weeks before animals began exhibiting clinical symptoms.

“That knowledge can change how you move animals on and off farm, (and how) you manage the parlor,” Poulsen said.

Only four herds in Wisconsin, all managed by the University of Wisconsin system, are being surveilled prior to the impending federal order, Poulsen said. He said he believes fear of loss of milk markets is preventing many dairy farmers from participating in surveillance voluntarily.

“We have never once — not one farm — lost a milk market,” Poulsen said. “Pasteurization is 100% effective.”

Poulsen allays those fears by referring to the 100-year-old Pasteurized Milk Ordinance, created to control the spread of tuberculosis in milk, which Poulsen said is 100 times stronger than the flu virus. Herds that have cases of TB are not exempted from shipping milk, Poulsen explained, because of the PMO.

“We know our industry is not a Wisconsin industry,” Poulsen said. “It’s a national industry, and we need to protect it as a national industry.”