A farmworker in Michigan is the second person to become infected with the current H5N1 bird flu virus.
The farmworker had mild symptoms and has since recovered, local health officials said.
According to Michigan’s chief medical executive, Natasha Bagdasarian, the current health risk to the public remains low, but the virus has circulated in dairy and poultry farms across the country this spring.
Here’s what we know about the bird flu infections.
Avian influenza, commonly called bird flu, usually spreads in birds and other animals but can infect humans if they come in contact with an infected animal’s body fluid.
It was first detected in dairy cows in March but data from viral samples found that it had been circulating in cattle for at least four months and caused a drop in milk production.
The U.S. Department of Agriculture (USDA) has confirmed that there are outbreaks in 51 cattle herds across the country in states including Michigan, New Mexico, North Carolina, Kansas, Colorado, Idaho, Ohio, South Dakota and Texas.
“This disease is deadly to domestic poultry. While it causes less severe illness in cattle than in poultry, the disease remains of concern for all livestock and also for humans who come into contact with infected animals,” the USDA said in an update Wednesday.
Since 2022, there have been two human cases related to bird and dairy exposure in the United States. One case was reported in Colorado in 2022 and one reported in Texas earlier this year.
A Texas man working on a commercial dairy farm contracted the bird flu earlier this year and had minor symptoms. He received antiviral treatment and is recovering. His household members did not become sick, the CDC said.
The Michigan farmworker was confirmed this week to be the second person infected in 2024 with the bird flu and reported similar symptoms, which indicated an eye infection.
The worker was enrolled in the state’s active monitoring program, but officials did not say when he was tested or when the positive test was reported.
Officials said it was reassuring that the worker’s nasal sample tested negative while his eye swab tested positive, meaning it “reduces the likelihood” of a respiratory route of transmission.
The infection is spreading rapidly among cattle, public health and infectious disease experts say the United States has an incomplete picture of how the virus is spreading across the country.
Officials stressed the importance of more farmworkers signing up to participate in the screenings. They said they caught the Michigan worker’s infection because they were looking for it and he was enrolled in the monitoring program.
“Today’s news underscores the continued importance of limiting nonessential farm visits, including farm tours and field trips, as well as the use of personal protective equipment when working with livestock,” Michigan Department of Agriculture and Rural Development (MDARD) Director Tim Boring said in a statement.
While health officials have said the risk of catching the infection remains low, they also say people that have jobs or recreational activities that could expose them to infected birds, cattle or other animals are at higher risk and should take precautions.
The USDA said it is confident that the country’s meat supply is safe.
Researchers did a study on ground beef purchased from local retailers in states with confirmed infected herds and incubated it with the virus to determine if the virus would remain after the beef was cooked.
No virus was detected in burgers cooked to 145 and 160 degrees Fahrenheit, meaning if meat is cooked to the recommended temperature, it’s sufficient to kill any infection.
The virus has been found in high levels in the raw unpasteurized milk of infected cows. The Centers for Disease Control and Prevention warned that people who drink raw milk could become infected, but the agency has long warned that raw milk is considered one of the “riskiest” foods to consume.
Viral remnants have been found in samples of milk sold at local retailers, but the Food and Drug Administration said the products are safe to drink since they’ve been pasteurized and that process kills the virus.
Bird flu is also not transmissible by eating properly cooked poultry and eggs.
