CHICAGO (CBS) — Three cases of Legionnaires’ disease confirmed in just two days at a senior living community in McHenry County.

State health officials said the third case linked to McHenry Villa was confirmed Thursday. They along with county health officials and workers are now trying to determine the source.

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At the McHenry Villa Senior Living Community, there were no obvious signs posted warning of Legionnaires. But state health officials said three cases are linked to the facility.

Legionnaires is a serious lung infection that people can get by breathing in small droplets of water containing Legionella bacteria.

In September, the facility flooded after a water pipe burst, but McHenry Villa’s executive director said they do not know if that flooding had anything to do with the cluster of Legionnaires’ cases.

According to state health officials all three residents had potential outside exposures.

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Two of those potentials exposures were at Centengra Hospital-McHenry which is now owned by Northwestern Medicine.

In a statement, a hospital spokesperson said in part “within the last month, we completed a routine water test at our McHenry Hospital and the results showed there was no Legionella. We do not believe our hospital was the site for this exposure.”

The executive director at McHenry Villa said they are notifying all residents and staff as well as following all recommendations to minimize exposure to everyone.

Also, a third case of Legionnaires’ disease was reported at the Warren Barr South Loop nursing home.

Two cases at the center were reported in October.

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Investigators believe the infected resident was exposed to the bacteria before the facility switched to bottled water while environmental assessments are being done.