Measles is 'most infectious disease,' IDPH is prepared to stop the spread

Illinois (WAND) — Measles cases are rising across the United States. In 2024, the CDC totaled 285 cases for measles. Now, just three months into 2025, there have been 280 cases reported.

What is measles?

Measles is a highly contagious respiratory virus that can cause rash and fever. In severe cases, it can cause blindness, pneumonia, swelling of the brain, and even death. According to the Illinois Department of Public Health, 1 in 1000 cases result in death and 1 in 20 cases cause hospitalizations. In regards to infection, 1 in 10 patients will deal with a more severe disease, and 1 in 5 will get pneumonia.

The CDC considers measles to be one of the most infectious diseases. If there were a room of ten unvaccinated people, nine of those ten people would get infected if exposed to a person with measles.

Measles infections spread when someone that is infected coughs or sneezes, and an uninfected person breathes it in. It can also stay on surfaces; if someone touches the surface, and then touches their nose or their eyes, they can infect themselves. It can also stay suspended in the air for two hours after an infected person leaves the room.

Additionally, a person with measles can be infectious before they even present with symptoms. People can spread the measles four days before symptoms -- like the tell-tale rash -- appear, and four days after the symptoms onset they are still infectious and can spread it to others.

Stopping the spread

Judy Kauerauf, the Communicable Disease Section Chief with the IDPH explained that the best prevention method for measles is getting vaccinated. "The vaccine is very effective. With even one dose, it's 93% effective. And with the two doses, it's 95%."

Kauerauf clarified that Vitamin A does not prevent measles. "Vitamin A is something that clinicians may use for someone that has had been diagnosed with measles. But it absolutely will not prevent you from getting infected, or cause the same level of prevention of getting the vaccine."

In addition to protecting yourself, vaccinating protects those around you. Herd immunity protects small children who cannot get vaccinated, or people who have health conditions or are immunosuppressed.

If you are concerned if you are protected from measles via vaccine, you can speak to your physician to see if they would recommend a serologic test to check to see if you have immunity.

IDPH preparations

The CDC is not connecting the outbreaks in West Texas and New Mexico to the other cases across the country. They attribute cases outside those two states to traveling. "CDC put out with a health alert recently," Kauerauf said, "advising with upcoming travel, that persons that are traveling, to make sure that they are up to date on vaccines."

Kauerauf said the vaccine rates in Illinois have been declining for the last few years. "Our rates were at 97.5% in 2018, 2019 and then dipped just slightly, to 97.3% in 2021. But this current or the most recent data for which we have 23-24 school year, we're at 95.9%."

The vaccination rate in Gaines County in Texas -- the epicenter where the outbreak stems from -- is below 82%. Kauerauf explained that based off the rate of vaccinations in Illinois, IDPH has systems in place to control the situation. "95% are already vaccinated, you only have 5% [unvaccinated]. Once the virus is introduced, it then becomes the response that helps to curtail the outbreak."

IDPH has an in-depth system for contact-tracing infected patients, including identifying exposure locations. "Every time we go through an outbreak, we, we get stronger and we think about ways we could do things to be more efficient and effective." Kauerauf said.

If a patient has been exposed and isn't fully vaccinated, their doctor can administer a dose of the vaccine. "It's what we call post-exposure prophylaxis." "With a single dose of measles [vaccine] can protect someone from developing disease, or very severe disease. Measles has a longer incubation period, so getting that dose and how quickly the vaccine works to create that protection and that immunity -- a dose of vaccine can actually serve to prevent illness post-exposure."