How common is the Legionella infection?

Infection by Legionella, despite its recent discovery, is fairly common. Most of us have, at some point in our lives, encountered this bacteria and have subsequently built up antibodies against it. 95% of those who come into contact with it will develop Pontiac Fever, which can easily pass for normal influenza. It has also been speculated that infection by Legionella is responsible for suburban neurosis (aka Sick Building Syndrome) – sore throat, slight headache, tiredness – although findings are, at this time, inconclusive. Most of those who develop full-blown Legionnaires’ Disease are those who are old, very young or whose immune systems have been compromised by disease or the environment.

Some major outbreaks of Legionnaires’ Disease and other Legionella-caused diseases are summarised in the table below:

Year

Country

Place

Disease

No. infected

Deaths

2002

Tennessee, USA

Restaurant

Pontiac Fever

100

0

2001

Murcia, Spain

Downtown neighbourhood

Legionnaires’ Disease

745

4

2000

Melbourne, Australia

Melbourne Aquarium

Legionnaires’ Disease

113

2

1999

Netherlands

Flower Show

Legionnaires’ Disease

188

4

1998

Melbourne, Australia

Victoria

Legionnaires’ Disease

270

0

1997

Singapore

Air-conditioned office buildings

Sick Building Syndrome

560

0

1985

England

Stafford Hospital

Legionnaires’ Disease

101

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