WASHINGTON, D.C. – The USDA has ordered that certain dairy cattle be tested for highly pathogenic avian influenza (HPAI) before the cattle can be transported across state lines. The move is designed to protect the country’s livestock industry from further spread of the disease, the agency said.

In addition, the U.S. Food and Drug Administration (FDA) said last week traces of the bird flu had been found in milk purchased in grocery stores, according to media reports. The FDA said it believes milk is safe to drink because of the pasteurization process and the diversion or destruction of milk from sick cows.

The federal order requiring mandatory testing for interstate movement of dairy cattle was effective April 29. The USDA’s Animal and Plant Health Inspection Service (APHIS) issued guidance about the order on April 26.

According to the guidance, lactating dairy cattle are required to receive a negative test for Influenza A virus prior to interstate movement. The milk samples must be tested at an approved National Animal Health Laboratory Network (NAHLN) laboratory. Samples must be collected by an accredited veterinarian, a state licensed veterinarian, or a sample collector approved by the appropriate state animal health official, APHIS said.

Sample collection and testing must take place no more than seven days prior to interstate movement, the guidance said.

Nonlactating dairy cattle – including heifers, dry cows and bull calves – are not currently subject to testing for interstate movement, APHIS said. Clinical lactating dairy cattle are ineligible for interstate movement or movement to slaughter, the agency noted.

Nonclinical lactating dairy cattle moving interstate directly to slaughter are also not required to have a pre-movement test, but must move on a certificate of veterinary inspection or other documentation of movement approved by and provided to the sending and receiving state animal health officials, APHIS said.

Laboratories and state veterinarians are required to report positive Influenza A results in livestock to APHIS.

The agency said it will reimburse for all pre-movement testing at NAHLN laboratories. As of press time, APHIS said it will not reimburse for sample collection or shipping.

Dr. Bret Marsh, state veterinarian with the Indiana State Board of Animal Health (BOAH), said it’s uncertain how many dairy cattle in Indiana may need pre-movement testing. The state has 698 grade A dairy operations housing about 190,000 cattle, he said. Marsh spoke during an April 26 call updating commodity partners, producers and veterinarians.

“Based on our estimation, most of the lactating dairy cattle stay on a site during that lactation period and only after they’re dry they may move elsewhere,” he explained. “There may be some testing but there may not be a broad number of tests based on the practices that take place here in the state.”

As of press time, no cases of bird flu in dairy cattle had been found in the state, according to BOAH.

Since late March, USDA and other agencies have been investigating the emergence of the virus in dairy cows. As of April 26, the presence of the HPAI virus has been confirmed on at least 34 dairy cattle premises in nine states – Colorado, Idaho, Kansas, Michigan, New Mexico, North Carolina, Ohio, South Dakota and Texas.

USDA said it has identified spread between cows within the same herd, spread from cows to poultry, spread between dairies associated with cow movements, and cows without clinical signs that have tested positive.

As for the safety of the nation’s milk supply, FDA said in a release that pasteurization is likely to inactivate the virus, but the process is not expected to remove the presence of viral particles.

“Therefore, some of the samples collected have indicated the presence of HPAI using quantitative polymerase chain reaction testing,” the agency said. “To date, we have seen nothing that would change our assessment that the commercial milk supply is safe.”

Additional testing was underway at press time.

Pasteurization kills harmful bacteria and viruses by heating milk to a specific temperature for a set period of time to make milk safer, FDA noted.

“Even if virus is detected in raw milk, pasteurization is generally expected to eliminate pathogens to a level that does not pose a risk to consumer health,” FDA explained. “However, pasteurization is different than complete sterilization; sterilization extends shelf life but is not required to ensure milk safety.”

FDA said it recommends consumers not drink raw milk, or milk that has not been pasteurized. The agency said it has also recommended that producers take precautions when discarding milk from affected cows so that the discarded milk does not become a source of further spread.

“While it is still unclear exactly how virus is spreading, the virus is shed in milk at high concentrations,” APHIS said. “Therefore, anything that comes in contact with unpasteurized raw milk, spilled milk, etc., may spread the virus including other animals, vehicles, and other objects or materials. Therefore, both dairy and poultry producers should re-double biosecurity efforts and be vigilant about monitoring for and controlling disease in their herds and flocks.”

The USDA’s actions underscore the continued animal health concern and focus on the well-being of animals and those who care for them, Gregg Doud, president and CEO of the National Milk Producers Federation, said in a statement.

“The presence of this virus in dairy herds, as well as dairy farmers’ own commitment to animal and human health, makes USDA’s actions on testing and interstate travel appropriate,” he said. “Dairy farmers stand ready to take a proactive approach to ensuring that we better understand the spread of the virus, do what we can to limit that spread, and ensure the health of our animals and workers.”