Legionnaires' disease is an uncommon form of pneumonia. The disease has no particular clinical features that clearly distinguish it from other types of pneumonia, and laboratory investigations must therefore be carried out in order to obtain a diagnosis. The following microbiological and epidemiological case definitions are used for surveillance purposes:
MICROBIOLOGICAL DEFINITIONS
Confirmed case:
A clinical diagnosis of pneumonia with laboratory evidence of one or more of the following:
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Isolation (culture) of legionella species from clinical specimens
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Seroconversion (a four-fold or greater increase in titre) determined
using a validated indirect immunofluorescent antibody test (IFAT)
incorporating a monovalent L. pneumophila serogroup 1 antigen.
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The presence of L.pneumophila urinary antigen determined using
validated reagents/kits.
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Presumptive case:
A clinical diagnosis of pneumonia with laboratory evidence of one or more of the following:
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A single high titre of 128 using IFAT as above (or a single titre of
64 in an outbreak)
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A positive direct fluorescence (DFA) on a clinical specimen using
validated monoclonal antibodies (also referred to as a positive result
by Direct Immunofluorescence (DIF)).
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The incubation period ranges from 2 to 10 days but is usually 3 to 6 days. In rare cases some people may develop symptoms as late as three weeks after exposure.
| TREATMENT |
Erythromycin is effective in treating the disease.
| CRICKET ST THOMAS OUTBREAK |
Revised 17 March 2003
An outbreak of Legionnaires Disease has been declared centred around the hotel and leisure complex at Cricket St Thomas (specifically a jacuzzi).
Nearly 4,000 people who may have come into contact with the facilities before 27 February 2003 have been contacted to make them aware of the situation and to ask them to fill in a health questionnaire. To date a total of 11 people have been diagnosed, including one death in a woman from Hertfordshire.
The inquiry is ongoing and the suspect system closed since 27 February. No cases in people exposed after 27 February have been detected adding weight to the theory (and also giving cause for belief that the source has been identitifed and eliminated).
If your patient has been to Cricket St Thomas hotel this year, please phone the Somerset Health Protection Unit on 01823 333491.
| FURTHER INFORMATION |
| PHLS Legionnaires information |