Legionella: the Silent Passenger
November 20, 2017
This is the first study linking Legionnaires’ disease to street cleaning (Emerg. Infect. Dis. 2017. vol. 23)
- A street cleaning worker in Barcelona was diagnosed with LD.
- Exposure to aerosolized water from the high-pressure hoses of cleaning trucks was the only risk factor identified in this case.
- An epidemiologic investigation revealed L. pneumophila serogroup 1 (LP SG1) in the tank water and foam liner of two trucks used by the worker in the preceding weeks before illness onset.
- Unfortunately, definitive transmission could not be confirmed. Since the patient was diagnosed by a urinary antigen test, there was no clinical isolate of Legionella that could be compared with the environmental strains.
- It was interesting to note that a second employee had been diagnosed with LD 4 years earlier.
Several factors were conducive for Legionella amplification.
- Untreated groundwater was used to fill the truck tanks.
- The trucks were infrequently disinfected (once per year) with 20-ppm chlorine solution.
- The foam tank liners absorbed water and were never cleaned or replaced.
- Water temperatures in the tanks ranged from 26-28oC.
Foam tank liners were implicated as a potential reservoir for Legionella.
- The tanks were cleaned and disinfected according to guidelines for potable hot water systems, but continued to yield LP SG1 from samples of tank water, hose water, and foam.
- The foam was subsequently removed from the trucks and a water management plan was adopted.
Previous studies have implicated water tanks in asphalt paving machines and recreational vehicles as possible sources of Legionella.
