The rate of Legionella (also known as Legionellosis or Legionnaires disease) has been steadily rising in Windsor-Essex County (WEC), with 11 reported cases in 2021, 12 reported cases in 2022 and 14 reported cases in 2023. Legionella is caused by the bacterium Legionella and is found within natural water environments and human-made water systems such as cooling towers and hot tubs. The disease is transmitted by inhaling Legionella-contaminated, aerosolized water droplets and can cause flu-like symptoms or pneumonia. The typical incubation period is 2 to 10 days, but more commonly 5 to 6 days.
Valid Testing for Legionella
The following are approved tests for Legionella:
- L. pneumophila serogroup 1 urine antigen test (UAT).
- Standard culture for all Legionella species with confirmation to species level.
- Serogrouping of L. pneumophila and other Legionellae with 2 or more serogroups.
- L. pneumophila serum antibody tests.
- NAAT for L. pneumophila and Legionella spp.
While UATs are the most rapid and sensitive test that can be conducted, they only detect infection with L. pneumophila serogroup 1. Cultures allow for identifying specific strains, which is crucial for linking cases to a common environmental source. Due to the limitation of urine testing results, effective epidemiological comparison of clinical and environmental isolates is impossible, limiting the identification and investigation of potential outbreaks.
Recommendations
The WECHU strongly recommends that confirmatory cultures of lower respiratory secretions (e.g., sputum) be collected concurrently with urine if a healthcare provider is testing for Legionella.
For questions or concerns, please contact the Infectious Disease Department at the Windsor-Essex County Health Unit at 519-258-2146 ext. 1420 from 8:30 a.m. – 4:30 p.m. Monday to Friday.
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