A person in the United States who had contact with dairy cattle in Texas infected with highly pathogenic avian influenza (bird flu) has also tested positive, according to the Centers for Disease Control and Prevention (CDC).

The individual reported eye redness as their only symptom.

According to the CDC the person was told to isolate and is being treated with an antiviral drug for flu.

“This infection does not change the H5N1 bird flu human health risk assessment for the U.S. general public, which CDC considers to be low,” it added.

The case involves only the second person reported to have tested positive for bird flu viruses in the US.

Bird flu

According to the CDC it has been monitoring any signs of illness among people exposed to the bird flu virus since outbreaks were first detected in US wild birds and poultry in late 2021.

The US Department of Agriculture (USDA) confirmed last week (March 26) that bird flu had been detected in sick cattle in two dairy herds in Texas and two dairy herds in Kansas

The USDA said that it is continuing to investigate an illness among dairy cows that is “causing decreased lactation, low appetite, and other symptoms”.

It has also confirmed that the “presence” of bird flu had been detected in a Michigan dairy herd that had recently received cows from Texas.

According to the USDA “presumptive positive test results” have also been received for additional herds in New Mexico, Idaho, and Texas.

The department has detailed that the strain of the bird flu virus found in Michigan is very similar to the strain confirmed in Texas and Kansas that it said “appears to have been introduced by wild birds”.

“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,” the USDA added.

It also highlighted that among the dairies whose herds are exhibiting symptoms, the affected animals have recovered after isolation with “little to no associated mortality reported”. 

The department has outlined that 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”. 

It also said that the US typically has a more than sufficient milk supply in the spring months due to seasonally higher production.

Milk supply

The department has stressed that there “continues to be no concern about 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 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,” it added.

Meanwhile the US Food and Drug Administration (FDA) has said it is “not aware that any milk or food product from symptomatic cows is entering interstate commerce”.