Nine residents of Illinois’ McHenry County were sickened with Legionnaires’ disease in less than a month, according to the McHenry County Department of Health, and officials are scrambling to identify if any “common denominators” exist between the individuals who were sickened.

Residents of Algonquin, Crystal Lake, Huntley, McHenry and Wonder Lake in McHenry County were diagnosed with Legionnaires’ disease, a sometimes-fatal, upper-respiratory illness, between June 7 and July 1. Their ages ranged from 46 to 82 years old.

No link or common source has been identified as to why nine residents of five cities in one county have come down with the pneumonia-like illness.

“I can tell you eight people were hospitalized, (and) seven have been released,” Keri Zaleski, the McHenry County Department of Health public information officer, said in an email to the Woodstock Independent. “(Federal privacy) laws prevent any further information about this.”

None of the individuals sickened were patients or residents of long-term-care facilities, but they – along with other health-care providers and local municipalities – were being alerted “as a precautionary measure,” according to Zaleski.

Help with the investigation
The Illinois Department of Public Health (IDPH) is assisting in the investigation, and local officials have contacted the Centers for Disease Control and Prevention (CDC) to update them on the situation.

There were four cases of Legionnaires’ disease in McHenry County in 2017, nine in 2016, and three in 2015.

The county is located in northern Illinois, and its northern-most border lies on the Wisconsin state line. According to the 2010 census, it had a population of 308,760, making it the sixth-most populous county in Illinois.

Similar but different?
In neighboring Kane County, the county directly south of McHenry County, officials are investigating two cases of Legionnaires’ disease from May and June to determine whether they are related to the current situation in McHenry.

“For all we know, the cases are not related to what is going on in McHenry County,” Tom Schlueter, Kane County Health Department spokesperson, told the Aurora Beacon-News. “We’ll be working with the Illinois Department of Public Health and McHenry County to determine if we have any similar cases.”

The two cases are the only cases to be reported in Kane County this year, down from 17 cases confirmed in 2017.