TECHNICAL
67
Does Legionella
really affect us in our
daily lives?
By By Patrick Gordon
Just to recap. What is Legionella, or also known as
Legionnaires’ disease?
I have attached an extract copy of the
definition from an article published by the
SaNTHNet dated Friday, 06 October 2017:
Legionnaires’ disease is recognised worldwide as an
important cause of both community- and hospital-
acquired pneumonia. It is caused by Gram-negative
bacilli of the Legionella genus. The mortality rate
in infected individuals ranges between 10 – 20%.
It was named after a large outbreak in 1976 that
occurred at a meeting of the American legion, which
affected 221 people, causing 34 deaths. Legionella
bacteria are common and can be found naturally in
environmental water sources, including rivers, lakes,
natural pools and moist soil. Water temperatures
in the range of 20°C to 50°C favour growth of the
organism. Legionella pneumophila serogroup
1 is the most important species of Legionella that
causes disease in humans, although other species
can occasionally cause disease. Legionella spp.
may also cause Pontiac fever, a mild, self-limiting
flu-like illness.
Who can get Legionnaires’ disease?
All persons can develop Legionnaire’s disease.
However, the risk is higher in persons over the age of
50 years. Male gender, persons with immunodeficiency
syndromes or chronic underlying medical conditions
of the lung, heart or liver and smokers are also at
increased risk.
Where does Legionnaires’ disease occur in
South Africa?
Legionnaires’ disease Legionnaire’s disease may
manifest as sporadic cases, small clusters, or outbreaks
of disease that can involve hundreds of cases. It is also
an important cause of travel-related illness, and may
be acquired on cruise ships, in hotels and resorts. In
South Africa, both sporadic cases and outbreaks of
Legionnaires’ disease have been described. Serological
testing identified that approximately 8% of community
January 2020 Volume 25 I Number 11
acquired pneumonias are caused by Legionella
species. Prospective surveillance identified 21/1 805
(1.2%) cases of legionellosis amongst persons with
severe respiratory illness However, due to difficulties in
diagnosis and lack of awareness of the disease, very
few cases are diagnosed in South Africa at present.
It is very likely that sporadic cases, clusters and even
outbreaks occur and are missed.
How is Legionnaire’s disease transmitted?
Persons become infected by breathing in water droplets
containing the Legionella bacteria. Water droplets are
generated by spraying or bubbling air through water
in which the bacteria are present. Human-to-human
transmission of Legionella has never been documented.
The incubation period for Legionnaires’ disease is
2 – 10 days. Wherever water droplets can be created
there is a risk of infection, including:
• Hot and cold water systems (e.g. showers and taps)
• Cooling towers and evaporative condensers of air
conditioners
• Spa baths (jacuzzis) and whirlpool baths and natural
pools or thermal springs
• Turkish baths and saunas
• Ornamental fountains (particularly indoors) and
sprinklers
• Humidified food display cabinets
• Respiratory therapy equipment
Patrick Gordon, general
manager at CalAfrica
since June 2019, started
in the plumbing retail
business in 1985 with
the Boumat Group.
In 2000 he moved
from the retail to the
manufacturing sector
when he joined Cobra
Watertech. He remained
with the company
for 19 years, rising
rapidly in various roles
from product support
manager / product
development manager,
a role which was
expanded in 2005 to
national product support
manager with, latterly,
more than half his life
spent on technical
training. He has also
qualified as a facilitator
and assessor. He is the
featured personality in
the August 2019 issue of
Plumbing Africa.
How can Legionnaires’ disease be prevented?
The proper design, maintenance and temperature of
potable water systems are the most important method
for preventing the amplification of Legionella. Hot
water should be maintained above 60˚C and delivered
to taps at temperatures above 50˚C. Cold water
should be maintained below 20˚C. Plumbing systems
should be flushed regularly, and low flow areas
eliminated. There are currently no vaccines to prevent
Legionnaires disease.
www.plumbingafrica.co.za