Second human case of bird flu linked to dairy cows found in Michigan

A second person in the United States has been infected with avian flu linked to dairy cows, the Michigan Department of Health and Human Services reported Wednesday.

The individual, a farmworker who was regularly exposed to infected livestock, had mild symptoms and recovered, the department said.

“The current health risk to the general public remains low,” Dr. Natasha Bagdasarian, Michigan’s chief medical officer, said in a news release. “We have not seen signs of sustained human-to-human transmission at this point. This is exactly how public health is supposed to work, when it comes to early detection and surveillance of new and emerging diseases.

The individual was being monitored for symptoms following exposure to infected dairy cows, the Centers for Disease Control and Prevention said in a statement. The person developed conjunctivitis, or pink eye, and a sample taken from the eye tested positive for the virus.

This is the second case of a person developing pink eye following avian flu infection. It was also the only symptom seen in the Texas dairy worker who was diagnosed in March in the first documented case of transmission of the virus from dairy cows to humans.

The CDC said it was sequencing samples taken from the Michigan employee to determine whether the virus had mutated in a way that allowed it to spread more easily between people.

The Michigan Department of Agriculture and Rural Development confirmed additional cases in cows this week, bringing the total number of infected herds in the state to 19 as of Wednesday.

Nationally, at least 51 herds across nine states have been affected, according to the U.S. Department of Agriculture. In addition to the Michigan herds, dairy cattle in Colorado, Kansas, Idaho, New Mexico, North Carolina, Ohio, South Dakota and Texas have also tested positive for bird flu.

Federal health officials are expected to hold a news conference on the matter later Wednesday afternoon.

On Tuesday, CDC Principal Deputy Director Dr. Nirav Shah asked state and local health officials to continue monitoring the flu “at increased levels” throughout the summer, even though the flu season typical is complete and virus detection testing is complete. falls to a minimum at this time of year.

Avian influenza, also known as H5N1, is a type of influenza A virus.

Shah said the CDC recommended states “increase the number of influenza A virus-positive samples submitted for subtyping to help detect even rare cases of human H5N1 virus infection in the community,” the agency said in a press release Tuesday.

Since the H5N1 virus was first identified in 1997, just over 900 cases have been documented worldwide in humans. More than 50% of these patients died, according to the CDC. But this mortality rate may be overestimated, as cases can also be mild and go unnoticed.

This is the third case of H5N1 in the United States. In 2022, a Colorado inmate was diagnosed with the virus. The man worked on a commercial farm and culled birds suspected of being infected. His only symptom was fatigue and he recovered with a course of Tamiflu.

There is currently no evidence that H5N1 is transmitted from person to person. None of the people living with the Texas dairy worker got sick.

The CDC recommends that anyone in contact with dairy cattle wear protective equipment, including safety glasses, waterproof aprons and boots that can be disinfected.