Los Angeles, California — Health officials are addressing concerns after Legionella bacteria was discovered in a cooling system at the Los Angeles County Medical Examiner’s Office and an employee later tested positive for Legionnaires’ disease.
The discovery was first made in May 2026 during maintenance work at the facility near downtown Los Angeles, according to reporting by NBC4. Officials later notified employees in the affected buildings about the finding.
Although an employee tested positive for the disease, authorities have not publicly established whether the infection was connected to the contaminated cooling system. The worker’s identity and current condition have not been disclosed.
Legionella Bacteria Found in Office Cooling System
The bacteria was detected in a cooling system at the Los Angeles County Medical Examiner’s Office during maintenance work in May 2026.
Legionella can grow in certain building water systems and spread through tiny contaminated water droplets or mist. Cooling equipment and plumbing systems can provide conditions that allow the bacteria to multiply if they are not properly maintained. Employees in the affected buildings were notified later in the year.
A spokesperson for the Medical Examiner’s Office declined to answer questions about the incident and referred inquiries to the Los Angeles County Department of Public Health.
The discovery has raised concerns about possible exposure in the workplace. However, the available information does not establish that the cooling system was responsible for the employee’s infection.
Employee Tests Positive for Legionnaires’ Disease
The Los Angeles County Department of Public Health confirmed that an employee tested positive for Legionnaires’ disease.
“The Los Angeles County Department of Public Health was notified of one Los Angeles County employee who tested positive for Legionnaire’s Disease,” a department spokesperson said.
Officials have not released the employee’s identity or provided details about the person’s health condition.
The department also reported that no additional cases had been identified among people with shared exposures to the employee.
“To date, no additional cases have been identified with shared common exposures to this individual,” officials said.
The distinction is important because finding Legionella in a building system and identifying a person with Legionnaires’ disease do not, by themselves, prove that the two events are directly connected.
Further information about the investigation and any additional environmental testing has not been detailed in the information released publicly.
What Is Legionnaires’ Disease?
Legionnaires’ disease is a serious type of pneumonia caused by Legionella bacteria. People generally become infected by breathing in small droplets of water containing the bacteria.
These droplets can come from contaminated plumbing systems, cooling equipment and other water sources that produce mist. The infection does not typically spread directly from one person to another.
Los Angeles County health officials have described Legionella as bacteria that are “commonly found in building plumbing systems, especially in older buildings.”
The bacteria’s presence in a water system does not automatically mean that people will become ill. The risk depends on factors including bacterial growth, the way contaminated water becomes airborne and whether people are exposed to the droplets.
Symptoms Can Develop Days After Exposure
Legionnaires’ disease can cause several symptoms associated with pneumonia and other respiratory illnesses.
Common symptoms include:
- Fever and chills
- Coughing
- Headaches
- Shortness of breath or difficulty breathing
- Other symptoms associated with respiratory infection
According to the U.S. Centers for Disease Control and Prevention, symptoms generally develop two to 14 days after exposure.
Older adults, smokers and people with weakened immune systems or certain underlying health conditions face a higher risk of developing severe illness.
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Legionnaires’ disease can be serious, but it is usually treatable with antibiotics. Anyone experiencing concerning respiratory symptoms after a possible exposure should contact a healthcare professional.
How Officials Monitor Legionella Risks
Public health agencies monitor Legionnaires’ disease cases and investigate potential sources of exposure when necessary.
Los Angeles County officials said healthcare providers are required to report symptomatic cases, allowing public health authorities to track infections and monitor higher-risk settings.
When Legionella is detected in a building’s water system, appropriate follow-up may involve assessing the system, evaluating potential exposure risks and determining whether corrective measures are needed.
However, the publicly available details in this case do not specify what remedial work, if any, was completed after the bacteria was discovered in May.
What Happens Next?
The key unanswered question is whether the employee’s infection was associated with the Legionella detected in the cooling system.
Officials have not publicly confirmed a direct link, and no additional cases involving people with shared exposure to the employee had been identified at the time of the reported update.
The discovery highlights the importance of maintaining building water systems and responding promptly when potentially harmful bacteria are detected.
Further details from the Los Angeles County Department of Public Health could clarify the extent of the investigation, the status of the affected cooling system and whether additional precautions were necessary.
What do you think workplaces should do when potentially dangerous bacteria are found in building water systems? Share your thoughts in the comments below.
