The case was confirmed in a dairy worker in Colorado.
A fourth case of avian influenza linked to the ongoing bird flu outbreak in dairy cows was confirmed in a Colorado dairy worker on Wednesday, according to the Centers for Disease Control and Prevention (CDC).
So far, one case has been reported in Texas and two in Michigan.
As with previous cases, the patient is a dairy worker who had contact with cows that tested positive for H5N1 avian influenza.
The worker had been under surveillance due to exposure to infected cattle and had reported symptoms to state health officials.
Test results at the state level were inconclusive, but samples sent to the CDC for additional testing tested positive for influenza A, federal health officials said.
The patient only complained of eye symptoms and was treated with oseltamivir, an antiviral drug used to treat influenza, and subsequently recovered.
The CDC says the risk to the general public remains low, but advises people to avoid close, prolonged, or unprotected contact with sick or dead animals, as well as unprotected contact with animal waste, garbage, unpasteurized milk, or any material that has been in contact with or near an animal suspected or confirmed to have avian influenza.
In early March, the U.S. Department of Agriculture announced that a strain of avian flu that has sickened millions of birds across the United States has been identified in several mammals this year.
Weeks later, federal and state public health officials announced they were investigating an illness that was causing symptoms such as reduced milk production and loss of appetite among mostly older dairy cows in Kansas, New Mexico and Texas.
The USDA statement At the time, the company said it had “no concerns about the safety of commercial milk and that the situation does not pose a risk to consumer health.”
Colorado currently has more reported cases of avian influenza in livestock than any other state, with 23 livestock herds affected in the past 30 days as of July 1. USDA Interactive Dashboard.
In late April, it was reported that fragments of avian flu had been found in samples of pasteurized milk, but the fragments were inactive remains of the virus and could not cause infection.
Federal agencies maintain that the U.S. commercial milk supply is safe because it is pasteurized and dairy farmers are required to destroy milk from sick cows, so the milk supply cannot be contaminated by sick cows.
The CDC said in a summary in May that part of the federal government’s preparedness efforts is preparing for “potential increased risks to human health” from bird flu, including packaging bird flu vaccine in vials to bolster the national stockpile.