Increased vigilance for legionellosis and testing recommendations
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To: Local Health Care Providers
Situation summary
Recent concurrent Legionella clusters in parts of Southern Ontario may signal an earlier-than-usual start to Legionella season in Ontario. In response, Public Health Sudbury & Districts is advising health care providers to remain alert for possible cases. There is currently no evidence of increased local transmission in our area, and the overall risk to the public remains low.
Clinical alert
Clinicians are advised to maintain a high index of suspicion for legionellosis in patients presenting with community-acquired pneumonia, particularly:
- adults 60 years and older
- individuals with risk factors such as:
- smoking
- chronic lung disease
- immunocompromising conditions
- recent exposure to large or complex water systems (e.g., travel, health care facilities, institutional settings)
- patients who have failed outpatient antibiotic treatment for community-acquired pneumonia
Testing recommendations
TWhere feasible, both the Urinary Antigen Test (UAT) and culture should be performed to optimize diagnosis and support public health investigation.
- UAT:
- allows for rapid diagnosis
- detects only Legionella pneumophila serogroup 1
- does not detect non–serogroup 1 infections
- does not allow for molecular typing or sequencing
- lower respiratory specimens (for example, sputum) for culture:
- identify additional species and serogroups beyond Legionella pneumophila serogroup 1
- enable genetic sequencing
- can link clinical specimens to environmental specimens through genetic sequencing during outbreak investigations
- support public health efforts to identify and control sources of exposure
Summary
Although current local risk remains low, heightened clinical vigilance is warranted. Early consideration of legionellosis and appropriate diagnostic testing are key to supporting effective patient care and public health response.
Reporting to Public Health
For questions, please contact Public Health Sudbury & Districts.
Sincerely,
Original Signed By
Emily Groot, MD, MPH, FRCPC (she/her)
Associate Medical Officer of Health