A second person in the United States has contracted bird flu linked to dairy cows, as announced by the Michigan Department of Health and Human Services on Wednesday. This individual, a farmworker regularly exposed to infected livestock, experienced mild symptoms and has since recovered.

"The current health risk to the general public remains low," stated Dr. Natasha Bagdasarian, Michigan's chief medical executive, in a press release. "We have not seen signs of sustained human-to-human transmission at this point. This is exactly how public health is meant to work, in early detection and monitoring of new and emerging illnesses."

The Centers for Disease Control and Prevention (CDC) confirmed that the individual was being monitored for symptoms after exposure to infected dairy cows. The farmworker developed conjunctivitis, or pink eye, and a sample from the eye tested positive for the virus, while a nasal sample was negative.

During a press briefing, Dr. Nirav Shah, CDC’s principal deputy director, indicated that the negative nasal sample provides some reassurance. "It reduces the likelihood, it does not eliminate, but it reduces the likelihood of a respiratory route of transmission," Shah said.

This is the second documented case in the U.S. where a person developed pink eye from bird flu. The first case involved a Texas dairy worker in March, whose only symptom was pink eye. Further genetic analysis of the virus from the Michigan worker will provide more insights into its transmission and any potential mutations.

Michael Osterholm, an infectious disease expert and director of the Center for Infectious Disease Research and Policy at the University of Minnesota, remarked on the situation: "I don’t think this changes the risk picture in terms of the virus being transmitted to people and then transmitted among people."

Dawn O’Connell, the Assistant Secretary for Preparedness and Response at the Department of Health and Human Services, announced that the government has initiated the "fill and finish" process for approximately 4.8 million doses of a vaccine matched to the bird flu. This preparation aims to expedite vaccine distribution if the virus becomes more widespread.

Dr. Shah has urged state and local health authorities to continue monitoring for flu at enhanced levels throughout the summer, despite the end of the typical flu season. So far, no increases in influenza-like illnesses have been detected around the Michigan farmworker's location.

Since the H5N1 bird flu strain was first identified in 1997, over 900 human cases have been documented globally, with a fatality rate exceeding 50%. However, this rate might be overestimated as milder cases could go undetected.

In the U.S., this is the third recorded case of H5N1. In 2022, a Colorado inmate working on a commercial farm culling infected birds was diagnosed with the virus, experiencing only fatigue and recovering with Tamiflu.

No evidence currently suggests that H5N1 spreads from person to person. None of the Texas dairy worker's household members fell ill. However, Shah emphasized that while the general public's risk remains low, farmworkers' risk is higher.

The CDC advises individuals in contact with dairy cattle to wear protective gear, including safety glasses, waterproof aprons, and sanitizable boots. Osterholm anticipates more cases in the coming weeks, stating, "I wouldn't be surprised if we saw five, six, 10 cases in the next few weeks."

The Michigan Department of Agriculture and Rural Development reported additional infected herds this week, bringing the state's total to 19. Nationally, at least 51 herds in nine states, including Colorado, Kansas, Idaho, New Mexico, North Carolina, Ohio, South Dakota, and Texas, have tested positive for bird flu, according to the U.S. Department of Agriculture.