Street Cleaning – a new risk factor for Legionella?

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 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 26-28o

 

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.