Cluster of cases of Legionnaires’ disease in Langley

Legionnaires’ disease is a pneumonia caused by Legionella species. Legionella can grow and spread in manmade building water systems that aerosolize water such as cooling towers, hot tubs, decorative fountains and large plumbing systems. Legionnaires’ disease is increasing in frequency as the climate changes. Testing for Legionella can help Public Health in investigating and addressing environmental sources of Legionella to prevent further transmission.

Patients can get Legionnaires’ disease when they breathe in aerosolized water droplets containing Legionella. While most healthy people do not get Legionnaires’ disease from being exposed to Legionella, some are at higher risk for developing pneumonia, including the elderly, those who smoke tobacco, people with chronic lung conditions and those with immunocompromising conditions.

Consider testing patients for Legionella who are symptomatic with pneumonia-like symptoms (e.g., coughing, fever, shortness of breath, fatigue) and who indicate they have been in the commercial areas of the City of Langley, Willowbrook, and/or adjacent areas in Surrey within 19 days prior to symptom onset. Testing for Legionella is not recommended for asymptomatic patients regardless of whether they spent time in Langley.

While the cluster is under investigation, we recommend the following testing for Legionella in symptomatic patients (order in addition to usual diagnostic testing as indicated for pneumonia):

1. Community outpatients (samples collected at Lifelabs will be forwarded to the BC Centre for Disease Control (BCCDC) Public Health Laboratory for testing):
   
   • Respiratory sample (e.g., sputum) for culture and respiratory panel PCR, and
   • Urine antigen test for Legionella
2. Hospitalized patients:
   
   • Lower respiratory sample (e.g., sputum, bronchial washing, pleural fluid) for culture, and
   • Lower respiratory sample for nucleic acid testing, and
   • Urine antigen test for Legionella

Obtaining a lower respiratory sample for Legionella culture in addition to urinary antigen test is of particular importance. The Legionella urinary antigen test only detects Legionella pneumophila serogroup 1, whereas Legionella culture can detect other serogroups of Legionella pneumophila or other species of Legionella. Additionally, culture isolates can be typed and potentially linked to other cases and environmental sources.

For patients with pneumonia where Legionella is suspected, empiric antibiotic treatment should cover for Legionella (e.g., a fluoroquinolone, macrolide or tetracycline). Ideally, respiratory samples should be obtained before antibiotic therapy is started.

Patients with suspected or confirmed Legionella infection do not require isolation or contact precautions. Person-to-person spread of Legionella is exceedingly rare. For laboratory-confirmed cases, Public Health will follow-up and get case histories on potential environmental exposures. For patient information on Legionnaires’ disease, see the HealthLinkBC file. BCCDC requisition is available through the E-Lab Handbook.