Third Person Catches H5N1 Bird Flu, This Time With Respiratory Symptoms

A third dairy worker in the United States has tested positive for H5N1 highly pathogenic avian influenza.

The latest case involves a farmworker in Michigan, who has experienced respiratory symptoms, according to the Michigan Department of Health and Human Services. The first two cases—another in Michigan and one in Texas—had discharge from their eyes, but this third case has broader symptoms.

This is the latest human development in the bird flu outbreak that has affected many more cattle in at least nine states, based on reports compiled by the United States Department of Agriculture.

But is this a “holy cow” moment in this outbreak? Does this third human case represent a change in the virus properties that make it more likely to cause consequential disease in humans?

Well, a U.S. Centers for Disease Control and Prevention report indicated that the respiratory symptoms consisted primarily of a cough without any fever, in addition to a watery discharge from the eyes. This patient received oseltamivir, an antiviral treatment, has remained isolated at home and apparently has been recovering without complications.

The CDC is still in the midst of sequencing the genome of the virus captured from samples from the patient to see if the virus has evolved in any concerning ways. So far, there’s been no indication that it has spread from human to human in any way.

The absence human-to-human transmission is key. For an epidemic or a pandemic to occur among humans, there has to be sustained human-to-human transmission. It’s not as if every human works with, lives with and parties with cows. Therefore, the spread to date has been limited to humans who have had close interactions with cows. For example, this third individual reportedly may have caught the virus when interacting with a sick cow without wearing a face mask. The first Michigan case had contaminated milk splash in his eye.

Therefore, the CDC is saying that this third case currently “does not change CDC’s current A(H5N1) bird flu human health risk assessment for the U.S. general public because all three sporadic cases had direct contact with infected cows. Risk depends on exposure, and in this case, the relevant exposure is to infected animals. The risk to members of the general public who do not have exposure to infected animals remains low.”

If you do find yourself getting close to cattle (or birds for that matter), it’s a good idea to maintain some bovine intervention: Wear personal protective equipment and be on the lookout for any flu-like symptoms. Be cautious around any such animals as you may not be able to tell if they are infected. Cows don’t tend to say, “Dude, not feeling so good,” or “I got a fever and need some cowbell.”

Also, stay aware of what’s happening with this HPAI outbreak. The H5N1 HPAI may not currently be a larger threat to humans who don’t hang with cows or drink raw milk. But flu viruses can continue to mutate. And while most mutations may not make a difference, you never know when a given mutation may end up giving you the bird.