A person in Texas has been diagnosed with avian influenza following the recent discovery of the virus in dairy cattle, state officials have said.

The Texas Department of State Health Services said the human case of avian influenza A(H5N1) was identified in a person who had direct exposure to dairy cattle presumed to be infected with the virus.

So far, the US Department for Agriculture (USDA) has identified 12 cases in cattle, with New Mexico the latest state to declare an incident on April 1.

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Texas is the most prolific state, with seven herds affected.

According to the Texas state health department, the primary symptom of the first human case was conjunctivitis.

According to the CDC, this is the second human case of H5N1 flu in the United States and the first linked to an exposure to cattle.

Avian influenza A(H5N1) is a type of flu virus that usually infects wild birds and can spread to domestic birds and other animals.

It occasionally infects people, though it is extremely rare for it to be transmitted from one person to another.

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Initial testing shows the virus has not changed in a way to make it more likely to spread among humans.

The Texas Department of State Health Services said: “DSHS is providing guidance to affected dairies about how to minimise workers’ exposure and how people who work with affected cattle can monitor for flu-like symptoms and get tested.

“Illnesses in people with H5N1 flu infections have ranged from mild, such as eye infection and upper respiratory symptoms, to severe, such as pneumonia and death.”

Veterinary experts remain adamant that the H5N1 virus has not changed in the process and is therefore no more transmissible to humans.

“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 pasteurised before entering the market,” said a USDA spokesman.

“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.”