Oakland County health officials detail Legionella testing, remediation at courthouse and county buildings

Oakland County health and facilities officials told the Board of Commissioners on Dec. 26 that the county is conducting an ongoing Legionella (legionellosis) investigation after two cases linked to county addresses prompted environmental testing and remediation.

Kate Guzman, health officer for the Oakland County Health Division, said the county investigates every reported case of legionellosis and interviews patients to determine whether environmental testing is needed. Health staff reported 41 legionellosis cases in 2025 countywide and said the incubation period is commonly 5–6 days (range 2–14). Guzman emphasized that Legionnaires' disease is treated with antibiotics and is not typically spread person-to-person.

Diana McBroom, director of risk management, described the timeline: county facilities reported an employee diagnosed Nov. 6; coordinating calls with the health division and facilities occurred Nov. 18; samples were collected Nov. 25; Building 38E tested positive on Dec. 4; and additional sampling and remediation followed. Health staff said a shared-address investigation and state guidance (MDHHS outbreak definitions) were key to deciding when to shift to an outbreak investigation.

County facilities and risk-management staff described immediate remediation steps at affected sites: installation of 0.2-micron filters on fixtures, hyperchlorination and flushing at Building 38E, extension of flushing protocols, and provision of N100/N95 masks and a Legionella-specific nurse-on-call for employees. Facilities staff said filters were installed across high-priority locations and that staff temporarily remove filters to collect swab and bulk samples, then replace them.

Testing results presented to the board showed that initial sampling at Building 38E on Nov. 25 returned six positive samples; after hyperchlorination and flushing later rounds showed only one very low positive (reported as 0.8 colony-forming units in one location) and continued improvement across rounds. Courthouse sampling (first round Dec. 15) showed 6 of 23 positive samples, improving to 3 of 23 after targeted flushing and remediation. County consultants have taken over ongoing sampling, which the county intends to continue for nine rounds at Building 38E and for scheduled rounds at the courthouse.

Officials said they are prioritizing additional testing at high-risk locations including the main jail and jail annex, Port Complex East and West wings (separate plumbing loops), Children's Village, the North Oakland Health Center, and the medical examiner's office. A facilities representative said county campus flushing covers roughly 40 buildings.

County staff said they will work with a water consultant to implement immediate water management plans for higher-risk buildings and develop a longer-term formal water management plan. A water-safety committee is proposed to include facilities management, the health division, risk management, consultants and stakeholder representatives (courts, labor, board members) to improve coordination and information sharing.

Board members pressed staff about the perceived time between initial notification and sampling; health and risk-management officials said outbreak investigations follow prescriptive state protocols and that some sampling supplies used in investigative testing were issued through the state, which contributed to timing constraints. Commissioners requested a detailed timing plan and monthly updates; staff agreed to provide them.

The board received and filed the presentation; no formal policy action was taken during the meeting.