Measles can be deadly, and that's why health officials are so worried. One hundred thrity-one cases were reported during the first seven months of this year. There were seven outbreaks across the country.
For a typical year, health officials say one outbreak usually occurs, affecting 10 to 20 people. This year is different.
Measles is highly contagious, and that's why health officials are concerned about the recent outbreak.
"Healthy people who get measles can end up with pneumonia or Encephylitis - that's swelling of the brain - and people can die, so measles is a very serious disease," said Dr. Julie Morita, Chicago Department of Public Health.
On Thursday, the Centers for Disease Control announced that measles cases have been reported from coast to coast, striking 15 states, plus Washington D.C. Most of the states have had a few cases, but Illinois tops the list with the highest number of cases; 32 have been reported here.
There are 27 cases in New York and 19 in Washington state. The CDC says most of the cases happened because people, for religious or philosophical reasons, did not want to get vaccinated.
"I know the majority of school age children that were infected in Illinois were unvaccinated mainly because their parents felt that they didn't believe in the vaccine," said Morita.
Morita says studies prove the vaccines are safe. And she's concerned that the past will repeat itself.
In Chicago, health officials say the last measles epidemic happened in 1989-90. There were more than 2,200 confirmed cases. More than 600 people were hospitalized. And 12 victims died, mostly children. And now that children are headed back to school, Morita offers this advice.
"It's a great opportunity for parents to review their children's immunization records and make sure they're up-to-date and protected from serious diseases like measles," said Morita.
Several of the Illinois cases happened in DuPage County. Most were school age children. There was only one case in Chicago during that time frame. That was a man from Switzerland who works in Chicago.