The infection of a farm worker in Wisconsin with avian flu has been confirmed by the Centers for Disease Control and Prevention (CDC). (Stephen Ausmus | Agricultural Research Service, USDA)

A Barron County farm worker has been confirmed to have been infected with avian influenza, the state health department reported Friday. The confirmation was made by the federal Centers for Disease Control and Prevention (CDC).

With the CDC analysis in hand, “the case will now be reported as a confirmed human case” of the highly pathogenic avian influenza H5N1, the Wisconsin Department of Health Services (DHS) announced. It is the first reported case of the virus in a human in Wisconsin. 

The presumed infection was first reported Wednesday in a farm worker who was one of 19 people exposed to a poultry flock in Barron County where the avian flu virus was detected. The flock has been destroyed to prevent the spread of the virus. 

The individual has been treated with antiviral drugs and is recovering, according to DHS. 

Bird flu was found in a Kenosha flock of chickens and ducks, which will be destroyed to prevent the spread of the highly contagious virus. (Photo by Stephen Ausmus | Animal Research Services, USDA)

A farm worker in Barron County has tested positive for avian influenza after being exposed to a poultry flock infected with the virus, Wisconsin health officials said Wednesday. The woman is the first person identified with the infection in Wisconsin.

At the other end of the state, a case of the highly contagious disease has turned up in a Kenosha County poultry flock, according to the state agriculture department. The flock has been isolated and will be destroyed.

The risk of illness for the general public remains low, according to the Wisconsin Department of Health Services (DHS), while people working with infected animals or who might be otherwise exposed to them are at higher risk.

Also Wednesday, the federal government reported the first severe case of bird flu in a patient in Louisiana. That was believed to be associated with wild birds, not domestic poultry. 

The infected woman in Barron County was identified through a test at the Wisconsin State Lab of Hygiene. The diagnosis is pending confirmation at federal Centers for Disease Control and Prevention (CDC).

She was exposed to the Barron County poultry flock where the state Department of Agriculture, Trade and Consumer Protection (DATCP) identified an infection with highly pathogenic avian influenza (HPAI H5N1) last week. The flock was destroyed.

After the infected flock was identified, DHS and Barron County Health and Human Services began monitoring farm workers who may have been exposed to the birds, said Thomas Haupt, a DHS research scientist and epidemiologist, in an online news conference Wednesday.

The woman who tested positive was one of two people tested. 

“She had relatively mild symptoms but symptoms that would be consistent with influenza, including sore throat, slight fever, some fatigue, some eye discharge,” said Haupt. He said she was improving after being treated with an antiviral medication and was expected to make a full recovery.

Public health officials are monitoring another 17 people who were exposed.

State public health veterinarian Dr. Angie Maxted said when people are infected with a communicable disease, public health agencies contact family and other household members to test them for the illness and inform them about preventive measures.

The Kenosha flock where an H5N1 infection was reported Wednesday is a “backyard flock” — one that is raised for a family’s own use, with limited, local sales of eggs or other products, said Dr. Darlene Konkle, DATCP state veterinarian. The flock consisted of 88 chickens and five ducks.

Haupt said the Kenosha County residents who might have been exposed are being tested for the virus. There are no concerns that members of the general public were at risk, however. Maxted said that it appears only the flock’s owners were exposed to the birds.

According to DATCP, the birds from the flock where the infection was reported will not enter the food supply.

In addition, poultry within a 10 kilometer (6.2 mile) area of the Kenosha flock will be restricted from being moved on or off any premises, said DATCP, which establishes a control area around any premises where an infection is found.  

DATCP has a mapping tool that poultry producers and owners can consult to learn whether their poultry are in an active control area or surveillance zone.

Concern about the virus has been heightened for the last three years, with reports of infections in both wild and domestic birds in North America since December 2021.

Konkle said DATCP has been sending information to dairy, poultry and other livestock producers all year, encouraging them to improve biosecurity measures to prevent the spread of disease and protect their birds and animals.

The H5N1 HPAI virus is highly contagious and can be fatal to domestic poultry. The severity of the illness varies depending on its strain and on which species of animal it affects, according to DATCP.

The virus spreads by contact with infected birds, commingling with wild birds or their droppings, and through clothing or equipment used by people working with infected birds or animals.

DHS has a web page with guidance for Protective Actions for People. The department can provide a limited amount of surplus personal protective equipment for farm workers, businesses and processors from the department’s medical stockpile through its Office of Preparedness and Emergency Health Care.  

State law requires all Wisconsin livestock owners to register where their animals are kept, which helps health officials alert flock and herd owners.

Avian flu in domestic birds tends to increase late in the year, likely due to weather conditions and the flow of migrating birds through Wisconsin. “There’s more opportunity, when it’s circulating in these wild birds” for the virus to spread, Konkle said.

People who have contact with livestock and animals are at higher risk for exposure to the H5N1 avian flu virus and should avoid contact with sick or ill animals, said Maxted.

When they must be in contact, people should follow “common sense” precautions, washing their hands frequently and wearing protective clothing including gloves, respiratory protection and eye protection, she said, and clothing exposed to animals should be cleaned and disinfected.

Haupt said the DHS bureau of environmental and occupational health has been working with farmers and farm workers to inform them about the risks of avian influenza and precautions to protect themselves from the virus. The agency urges people who do get sick to take time off.

“If someone is sick, if you don’t have to work — don’t work,” Haupt said. “Stay home, give yourself time to heal.”

This report has been updated to correct the number of people in Barron County being monitored after avian flu exposure.