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PLUMBING CONNECTION
SPRING 2016
DESIGNING FOR HEALTHY HOSPITAL
WATER SYSTEMS
S
ince the first documented outbreak of Legionellosis in
Philadelphia in 1976, more than 42 Legionella species
have been identified. Hospitals are one of the highest
risk environments for Legionella as they have large and
complex water systems that are difficult to monitor, filter,
temper and flush. Couple this with the vulnerability of those
using the systems and the threat of Legionella in hospitals
intensifies.
So what exactly is Legionella and what measures can we
take to prevent it spreading?
BACKGROUND
Legionella bacteria occur everywhere in lakes and
rivers, although the concentration of Legionella in natural
habitats is low. Elevated temperature, inorganic and organic
contents of the water and the presence of biofilm play key
roles in its growth and spread. These factors may explain
why Legionella increases in density in artificial habitats
such as man-made warm water systems. The disease
causing bacteria start to multiply in water at temperatures
over 20°C with the highest concentrations found in water
samples of 30-40°C. Optimum conditions for Legionella
growth are found in warm stagnant water reaching a
temperature of around 35°C.
While the Legionella bacteria is commonly portrayed as
rare, scientific research has shown that this is not the case.
Research by the Centers for Disease Control and Prevention
(CDC) found that 70% of hospitals tested had Legionella
bacteria in their water systems.
LEGIONNAIRE’S DISEASE – TRANSMISSION AND RECENT
OUTBREAKS
The diseases caused by Legionella are collectively termed
Legionellosis. Legionnaires’ disease is the pneumonic form
of Legionellosis, while the benign flu-like form is called
Pontiac fever. Legionnaires disease has an incubation
period of 2-10 days and begins with a mild cough, malaise,
muscle aches, low fever and gastro-intestinal symptoms.
Later symptoms include high fever, alveolitis, kidney failure,
diarrhoea and bronchiolitis.
Legionellosis is transmitted by breathing in fine droplets
of water that contain the bacteria. It can’t be transmitted
person to person or by drinking contaminated water.
A significant outbreak of Legionnaire’s disease occurred
in February 2015 in New York, resulting in the death of
12 people with at least 100 others infected. In the UK,
clinical studies have shown that Legionnaires accounts for
around 3% of the 200,000 cases of community acquired
pneumonia’s diagnosed each year
1
. This means that the
actual number of cases occurring may be over 10 times
higher than the number of reported cases and could be
more than 5000 cases per annum. Additionally, worldwide
incidences of hospital-acquired Legionnaires disease
are increasing. While effective antimicrobial treatment
is available, this is often complicated by underlying
PLUMBING CONNECTION
TEAMS UP WITH
ENWARE
TO DISCUSS HOW YOU CAN HELP PREVENT LEGIONELLOSIS BY
MAKING SURE THAT THE WATER SYSTEMS IN BUILDINGS ARE MAINTAINED.
By integrating a thermostatic mixer into a point-of-use
mixer, the risk of Legionella is minimised.
LEGIONELLA