CHICAGO (CBS) — Cook County and Illinois public health officials have begun investigating a cluster of measles cases linked to a daycare center in Palatine.

In a joint statement, the Illinois Department of Public Health and the Cook County Department of Public Health said the cluster includes five infants who have ties to KinderCare Learning Center, located at 929 E. Palatine Rd. in Palatine.

“We are focused on ensuring the continued health and safety of the rest of our center,” KinderCare operators said in a prepared statement. “We are following Public Health officials’ guidance and excluding unvaccinated children and staff.”

The daycare center and its buses have been sanitized in response to the measles outbreak.

All five of the children are less than a year old, including four from the suburbs, and one from Chicago. Lab tests have confirmed measles cases in two of the children; the other three have been tentatively diagnosed with measles, but doctors were waiting for lab tests to confirm it.

All of the children are reported to be at home and doing OK.

“Individuals who are under the age of one or with certain clinical conditions cannot be vaccinated and are therefore at highest risk for measles. Residents are strongly encouraged to get vaccinated to protect themselves and the most vulnerable members of the community,” officials said.

Students, staff, and faculty at the daycare center have been notified, and anyone who hasn’t received a measles vaccination has been told to stay at home, and away from unvaccinated people for the next 21 days.

The nearby school district is also taking precautions because of the measles outbreak. Sixty-five kids who attend that KinderCare also go to Palatine’s Community Consolidated School District 15. They have all been vaccinated.

But about 200 other kids in the district have not. The district sent emails to parents saying they are working closely with health officials to keep children safe.

Officials said the source of the infection is unknown, and it’s unclear if the cases are linked to a measles case last month in the suburbs, or to the measles outbreak that has been linked to Disneyland.

Measles Fact Sheet

Cook County health officials predict there will be more measles cases associated with the Palatine daycare center, as many as 10.

Dr. Rachel Rubin stressed that measles is a serious illness with potentially serious complications. Previously, she says there have only been 10 documented cases in Illinois in the last five years.

Symptoms of measles include fever, red and sore eyes, runny nose, cough, and rash. Measles can cause more severe health problems, including pneumonia, encephalitis, and death; it is transmitted by coughing and sneezing, and can survive in the air and on surfaces for up to two hours. People who have measles are contagious from four days before a rash starts, through four days afterward.

“This situation continues to underscore the importance of getting vaccinated. Vaccinations are the safest, most effective way to protect individuals from measles and other potentially dangerous communicable diseases,” officials said.