- Sick dairy cows from Kansas and Texas have tested positive for bird flu.
- Federal and state veterinary and public health officials have been investigating an illness affecting cows in Texas, Kansas and New Mexico.
- There is currently no concern about the safety of the commercial milk supply or risks to consumers, USDA officials said.
Sick dairy cows in two states have tested positive for bird flu, federal officials said on March 25.
As of Monday, the highly pathogenic avian influenza (HPAI) virus was detected in unpasteurized, clinical milk samples from sick cattle at two dairy farms in Kansas and one in Texas, the U.S. Department of Agriculture (USDA) announced in a press release. A cow at another dairy in Texas also tested positive.
The USDA, the Centers for Disease Control and Prevention (CDC), and state veterinary and public health officials have been investigating an illness affecting mainly older dairy cows in those two states, as well as in New Mexico. Symptoms include decreased milk production and low appetite.
The infections appear to be due to wild birds, the USDA wrote. Farms have also reported finding dead wild birds on their properties.
“At this stage, there is no concern about the safety of the commercial milk supply or that this circumstance poses a risk to consumer health,” the USDA wrote.
Commercial milk supply is safe
Janet Buffer, with the Food and Policy Institute within the Milken Institute School of Public Health at George Washington University in Washington, D.C., said consumers do not need to be concerned about the avian flu virus or other viruses or bacteria when consuming pasteurized milk and milk products made from pasteurized milk.
“Milk that enters into the food system is tested and pasteurized to ensure it is safe for human consumption,” Buffer told Healthline. Pasteurization kills any viruses, bacteria or other microbes in the milk, without altering the milk’s taste, appearance or nutritional value.
In addition, milk from sick cows is diverted or destroyed so it doesn’t enter the food supply, the USDA wrote.
“The concern is when raw milk is purchased and consumed,” Buffer said.
Sales of raw milk, also known as unpasteurized milk, are regulated by each state. Many states have declared the sale of raw milk illegal, but others allow for its sale with conditions.
Raw milk can contain dangerous bacteria such as Salmonella, E. coli, Listeria and Campylobacter, or other harmful microbes. Raw milk is especially dangerous to children, older adults, pregnant women, and people with weakened immune systems.
Low risk to the public from bird flu
Federal and state agencies are conducting additional testing, including viral genome testing, the USDA said in its release. This will provide a better understanding of which strain or strains of the bird flu virus are involved in these cases.
Initial genetic testing by the National Veterinary Services Laboratories did not find any changes to the virus that would make it spread more easily to people. “[This] would indicate that the current risk to the public remains low,” the USDA wrote.
This is the first time HPAI has been detected in dairy cattle and only the second time it has been detected in a ruminant, the American Veterinary Medical Association (AVMA) said on March 25 in a press release.
Ruminants are animals that chew their cud, and include cattle, goats and sheep.
“The first detection of HPAI in dairy cattle in Texas and Kansas underscores the importance of adherence to biosecurity measures, vigilance in monitoring for disease, and immediately involving your veterinarian when something seems ‘off’,” AMVA President Dr. Rena Carlson said in the release.
For dairies whose herds are showing symptoms, on average about 10% of each affected herd is impacted, the USDA wrote in its release. Few or no cows have died as a result of their infection.
In addition, “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,” the department wrote.
What is bird flu?
The bird flu is a disease in birds caused by infection with avian influenza Type A viruses. These viruses occur naturally among wild aquatic birds but can infect domestic poultry such as chickens.
Avian influenza Type A viruses are classified into two categories:
- Low Pathogenic Avian Influenza (LPAI): The most common type, and causes no signs of disease or mild disease in chickens and other domestic poultry.
- Highly Pathogenic Avian Influenza (HPAI): Can cause severe disease and high death rates in infected poultry.
Some bird flu viruses can also spread to domestic animals such as cats and dogs, as well as to wild mammals.
Bird flu viruses don’t usually infect people, but can in rare cases. Infections in people range from no symptoms or mild illness to severe illness that can result in death. The bird flu viruses responsible for the most infections in people have been H7N9 and H5N1.
“Viruses jumping from one species to another should always be of concern,” Darin Detwiler, an associate teaching professor at Northeastern University and food safety advocate, told Healthline.
“This ‘flu’ has resulted in the killing of huge numbers of birds and impacted food availability and cost.”
From 2019 to 2022, the global avian flu outbreak has resulted in the loss of 40 million domestic birds and economic costs ranging from $2.5 to $3 billion, according to an industry report from the non-profit group FAIRR.
While pasteurization protects consumers from ingesting harmful pathogens in milk and milk products, Buffer said people should remain diligent when around domestic farm animals or wild animals. This will reduce the risk of becoming ill with any disease carried by those animals.
“If choosing to interact with animals such as cows, chickens, sheep and goats, always avoid touching your face with your hands, especially your eyes, nose and mouth,” she said, “and always wash your hands after coming into contact with the animals and their surroundings.”
What are the symptoms of bird flu?
Symptoms of bird flu infection in people include:
- eye redness (conjunctivitis)
- mild flu-like upper respiratory symptoms, such as cough, sore throat, and runny or stuffy nose
- pneumonia
- fever
- muscle or body aches
- headaches
- fatigue
- shortness of breath or difficulty breathing
Takeaway
Milk samples from sick cattle at two dairy farms in Kansas and one in Texas tested positive for highly pathogenic avian influenza (HPAI) virus, aka “bird flu” virus. A cow at another dairy in Texas also tested positive.
Officials from the USDA said there is no concern about the safety of the commercial milk supply due to the illness among cattle. Milk from affected animals is diverted or destroyed to keep it out of the food supply. Milk is also pasteurized, which kills any viruses, bacteria or other microbes.
Bird flu viruses occur naturally among wild aquatic birds, but can infect domestic chickens and other poultry. These viruses can also infect mammals, including domestic dogs and cats. In rare cases, people can become infected, with symptoms ranging from mild to severe.
