CHICAGO (CBS) – The number of mumps cases in Lake County has increased to four. Three of them are at Barrington High School.

CBS 2’s Sandra Torres has the story.

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The third case officially heightens the status to an outbreak and public health officials believe more cases will be reported in the coming days.

Barrington High School officially has a mumps outbreak.

“We now have three confirmed cases of mumps,” said Brian Harris, District 220 Superintendent.

Harris has been monitoring the situation closely, making sure parents, students and staff are informed.

“Make sure to share factual information in a timely and accurate fashion,” Harris said.

The number of cases fluctuate daily, but the Lake County Health Department reports that as of Wednesday there are four confirmed mumps cases in the county. Three of them at Barrington High School, two student with vaccines up to date and one adult who was not able to obtain his vaccination records. The fourth case in an adult in Barrington, not related to the school.

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“This number has been exceeded substantially,” said Victor Plotkin with the Lake County Health Department.

He said the county has not seen an outbreak like this in over 15 years.

“We have normally two to three cases per year only and with this outbreak, it is unfortunate, but we are optimistic,” Plotkin said.

He is optimistic, but as more cases are reported it is even more important to be aware of personal hygiene, especially if you live in the area.

“Cough etiquette is important and discarding used tissue is equally important,” Plotkin said.

As seen with confirmed cases, Lake County health officials said even with vaccines, there is a risk. But without vaccines, the number of cases at Barrington High School would have been much higher.

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That is why the health department wants everyone to have their vaccinations up to date, because in order for the outbreak to be declared over, there must be no confirmed cases at the location for 50 days.