US issues warnings after avian flu first

The US Centre for Disease Control (CDC) has revealed that a man has contracted Avian flu in what is thought to have been the first bovine to human transition.

The victim from Texas tested positive for highly pathogenic avian influenza (HPAI) A(H5N1) virus. The person had been exposed to dairy cattle in Texas presumed to be infected with the virus.

The news has prompted US health agencies to warn the population not to drink unpasteurised milk as it looks to contain the spread of the virus in cattle.

The patient reported eye redness (consistent with conjunctivitis), as their only symptom, and is recovering. The CDV said the patient was told to isolate and is being treated with an antiviral drug for flu.

The CDC added: “This infection does not change the H5N1 bird flu human health risk assessment for the US 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.”

It added the CDC is working with state health departments to continue to monitor workers who may have been in contact with infected or potentially infected birds/animals and test those people who develop symptoms.

This is the second person reported to have tested positive for influenza A(H5N1) viruses in the United States. A previous human case occurred in 2022 in Colorado. Human infections with avian influenza A viruses, including A(H5N1) viruses, are uncommon but have occurred sporadically worldwide.

“CDC has been monitoring for illness among people exposed to H5 virus-infected birds since outbreaks were first detected in US wild birds and poultry in late 2021,” it added. “Human illnesses with H5N1 bird flu have ranged from mild (e.g., eye infection, upper respiratory symptoms) to severe illness (e.g., pneumonia) that have resulted in death in other countries.”

The CDC added H5 bird flu is widespread among wild birds in the US and globally.

HPAI in dairy cows was first reported in Texas and Kansas by the US Department of Agriculture (USDA) on 25 March 25.

Unpasteurized milk from sick cattle collected from two dairy farms in Kansas and one in Texas, as well as a throat swab from a cow in another dairy in Texas, tested positive for HPAI A(H5) viruses that are widespread among birds globally. On 29 March the USDA’s National Veterinary Services Laboratories (NVSL) confirmed HPAI in a Michigan dairy herd that had recently received cows from Texas.

The CDC added: “According to FDA and USDA, there are not concerns with the safety of the commercial milk supply at this time because products are pasteurised 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, pasteurisation has continually proven to inactivate bacteria and viruses, like influenza, in milk. Pasteurisation is required for any milk entering interstate commerce for human consumption. FDA’s longstanding position is that unpasteurized, raw milk can harbour 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.”