The U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed the detection of highly pathogenic avian influenza (HPAI) in a dairy herd in Idaho. APHIS shared on Friday, March 29 that its National Veterinary Services Laboratories (NVSL) in Ames, Iowa, was working to confirm presumptive positive test results from an Idaho herd; this announcement is a follow up to that information.

This marks the first known case of HPAI in cattle in Idaho. To date, USDA has confirmed the detection of HPAI in dairy herds in Texas (7) Kansas (2), Michigan (1), and New Mexico (1).

The NVSL is currently performing confirmatory tests on presumptive positive results from Kansas, New Mexico, Ohio and Texas. It is important to note that, while these samples are from cattle with at least some clinical signs in common with other cattle diagnosed with HPAI, the presence of HPAI should not be considered confirmed until the NVSL analysis is complete.

APHIS has created a landing page with recent announcements pertaining to HPAI detections in livestock, as well as biosecurity information and other resources. Going forward, APHIS will post confirmed detections of HPAI in livestock on that landing page by 4:00 p.m. ET each day.

APHIS continues to work closely with the Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC), as well as state veterinary and public health officials, to investigate and diagnose the illness in dairy cows causing decreased lactation, low appetite, and other clinical signs.

USDA and federal and state partners will continue to share additional updates as information becomes available. APHIS has also prepared a Frequently Asked Questions document, which can be accessed here as well as a document with recommendations for state animal health officials, veterinarians, and producers, which may be found here.

On April 1, CDC reported that a person in Texas has tested positive for HPAI A(H5N1) virus; the CDC also stated in its announcement that this infection does not change the A(H5N1) bird flu human health risk assessment for the U.S. general public, which CDC considers to be low. However, people with close or prolonged, unprotected exposures to infected birds or other animals (including livestock), or to environments contaminated by infected birds or other animals, are at greater risk of infection. CDC has interim recommendations for prevention, monitoring, and public health investigations of HPAI A(H5N1) viruses.

Federal and state agencies continue to conduct additional testing in swabs from sick animals and in unpasteurized clinical milk samples from sick animals, as well as viral genome sequencing, to assess whether HPAI or another unrelated disease may be underlying any symptoms.

The NVSL has also confirmed that the strain of the virus found in subsequent states is very similar to the strain originally confirmed in cattle in Texas and Kansas that appears to have been introduced by wild birds (H5N1, Eurasian lineage goose/Guangdong clade 2.3.4.4b). Initial testing has not found changes to the virus that would make it more transmissible to humans. While cases among humans in direct contact with infected animals are possible, this indicates that the current risk to the public remains low.

There continues to be no concern that this circumstance poses a risk to consumer health, or that it affects the safety of the commercial milk supply because products are pasteurized before entering the market. Dairies are required to send only milk from healthy animals into processing for human consumption; milk from impacted animals is being diverted from the commercial milk tank or destroyed so that it does not enter the human food supply. In addition, pasteurization has continually proven to inactivate bacteria and viruses, like influenza, in milk. Pasteurization is required for any milk entering interstate commerce for human consumption. FDA’s longstanding position is that unpasteurized, raw milk can harbor dangerous microorganisms that can pose serious health risks to consumers, and FDA is reminding consumers of the risks associated with raw milk consumption in light of the HPAI detections.

Because of the limited information available about the transmission of HPAI in raw milk, the FDA recommends that industry does not manufacture or sell raw milk or raw/unpasteurized milk cheese products made with milk from cows showing symptoms of illness, including those infected with avian influenza or exposed to those infected with avian influenza. By exposure, FDA generally means cattle located on a premises with cattle with suspected or confirmed H5N1. Given the variety of premises sizes and the potential for state requirements, FDA recommends producers consult with state regulatory officials and their veterinarian for further guidance. At this time, the FDA is not aware that any milk or dairy product from symptomatic cows is entering interstate commerce. Furthermore, on farms where HPAI has been confirmed, or is suspected, if milk is intended to be used to feed calves or other animals (including pets), FDA strongly encourages that it be pasteurized or otherwise heat treated to kill harmful bacteria and viruses, such as influenza, before feeding to livestock or other animals. FDA posted a document with questions and answers regarding milk safety during HPAI outbreaks. Additional food safety information from FDA, including information about the sale and consumption of raw milk, can be found here.

Milk loss resulting from symptomatic cattle to date is too limited to have a major impact on supply and there should be no impact on the price of milk or other dairy products. Further, the U.S. typically has a more than sufficient milk supply in the spring months due to seasonally higher production.

Federal agencies are also working with state and industry partners to encourage producers and veterinarians to report cattle illnesses quickly so that we can monitor potential additional cases and minimize the impact and risk to farmers, farmworkers, consumers and other animals. Producers are urged to work with their veterinarian to report cattle illnesses quickly and practice enhanced biosecurity measures. More information on biosecurity measures can be found here.