256
What is interesting is thatmore of the 44outbreakswere causedbyhot and
coldwater systems (25%) thanby any other type of system. This challenges the
often held assumption that cooling towers cause most outbreaks. However,
while cooling towers caused fewer outbreaks in this study, they did cause
most of the individual cases of disease. Spa pool also were implicated in
causing 14% of the outbreaks, although most of the cases linked to spa pools
are classed as Pontiac Fever and not classic Legionnaires’ Disease.
Outbreaks by Failing (n=24 from 17 outbreaks)
This chart provides information as to the causes of individual outbreaks.
By a considerable margin, problems with the “Scheme of Control” have been
regarded as the failing that led to the outbreak. This strongly emphasizes the
need for clear, distinct actions, which would include tasks such as monitoring
of temperatures, flushing of little used outlets, inspection of water storage
0 10 20 30 40 50 60 70
Risk Assessment
Scheme of Control
Cleans and Disinfections
Training and Competence
