Measles case confirmed in Kane County, health department says

A Kane County resident has been confirmed to have measles, the Kane County Health Department said Monday.

The case is the fifth reported in the state so far in 2026, according to Kane County Health Department Executive Director Michael Isaacson.

Now, the health department, working with the Illinois Department of Public Health, is identifying and contacting individuals who may have been exposed — as well as reminding the public about the importance of vaccination against the disease.

Cases of measles, one of the most contagious viruses known to medicine, are on the rise in the United States.

Last month, the number of cases in the U.S. surpassed the tally for all of 2025, which had previously been the worst year for measles in more than three decades, the Associated Press reported. Like other diseases, however, it’s hard to say exactly how far-reaching the spread is, since some people don’t seek treatment when they get sick.

Illinois has also seen higher numbers in recent years, with the Illinois Department of Public Health reporting 91 cases since 2023, after seeing no reported cases in the several years prior.

But this recent case is Kane County’s first since 2019, and only its third in the past roughly 30 years, according to Isaacson.

Once a case is identified, the first thing the health department does is ensure that the person is isolated so they are not potentially exposing more people to the disease, Isaacson said.

At the same time, the health department is working to identify the places that person may have been so it can identify any potential contacts, according to Isaacson. The health department would then ensure that any contacts are up to date on their vaccinations, he said. If they’re not up to date, a contact would need to quarantine.

Investigating measles cases is “a very onerous process,” Isaacson said, because of how contagious it is.

The disease can spread through the air when an infected person coughs or sneezes, according to the state’s Department of Public Health. Symptoms can include high fever, cough, runny nose, red eyes and a rash that often begins on the head and then spreads.

Individuals are asked to follow any quarantine instructions provided by the Kane County Health Department or another public health authority and to monitor for symptoms for 21 days after a potential exposure, according to the county health department.

A person who develops symptoms and believes they may have been exposed to measles should call their healthcare provider before going to a medical office, urgent care or emergency department, the news release said, because it allows the facility to make appropriate arrangements to protect other patients and healthcare workers.

Although the county has not seen significant numbers of cases, Isaacson framed the broader issue in part in terms of falling vaccination rates.

In 2000, the U.S. eliminated local measles spread by maintaining high vaccination rates, but those rates have fallen in recent years to below the 95% coverage needed to prevent outbreaks. In November, international health officials will meet to determine if the U.S. and Mexico have lost their measles-free status.

“Even though the number of cases has been low, one thing that concerns us is the number of people who are opting not to vaccinate their children has continued to rise over the last several years,” Isaacson said. “So that’s leading to more cases of measles across the country.”

Two doses of the vaccine are about 97% effective, according to the news release from the county health department. And the individuals primarily at risk for the disease are those who are unvaccinated, Isaacson said.

And vaccination is not just about protecting yourself from measles, Isaacson added.

“(The) vaccine not only protects the person, but it protects the people around them, too,” he said.

The Associated Press contributed.

mmorrow@chicagotribune.com