New legionella test results from county buildings show at least one has signs of the bacteria. But county officials note it is two fewer than the previous round of tests.

Results from 23 samples collected Jan. 13 and 14 at the county’s circuit courthouse, 1200 N. Telegraph Road in Pontiac, found traces of legionella in a men’s room in the clerk’s vital records office.

Legionella is a bacteria found in the ground and in some water systems. The bacteria can cause a type of pneumonia called Legionnaire’s disease or a less-severe lung infection called Pontiac fever. County health officials have emphasized that such infections are rare.

The county has been testing water systems since November after a custodian’s Legionnaire’s disease was traced to the sheriff’s administration building on the county’s Pontiac campus.

In April 2025 a man diagnosed with Legionnaire’s listed the county’s circuit courthouse among the places he visited. That man later died, according to Lisa Brown, county clerk and register of deeds. The man has not been identified by name; the county custodian’s condition has not been shared with the media.

In addition to follow-up testing, the county is following what county spokesman William Mullan called “rigorous preventive measures,” including regular flushing, water temperature monitoring and temperature adjustments.

The county installed 300 filters and reinstalled three that malfunctioned, he said. Earlier this month, Brown told the county commission’s health and safety committee that at least one of the malfunctioning filters sprayed a man using a sink.

County tests will continue through May in areas where legionella was initially detected.

Last week the county started its routine-testing program to meet standards set by the U.S. Centers for Disease Control and Prevention. These tests are at buildings where legionella has not been detected.

Routine tests in the east and west wings of the courthouse and the medical examiner’s office on the county’s Pontiac campus showed no signs of legionella in the Jan. 23 results. Twelve samples were collected in the courthouse and five were collected in the medical examiner’s office. Buildings with clean-water results do not have to be immediately retested, under CDC guidelines.

Routine tests at the county jail will start Tuesday, Jan. 27.