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Cause:
Bacteria in the genus Legionella, commonly L.
pneumophila serogroup 1 but also other serogroups or
other species such as L. micdadei, L. bozemanii,
L. longbeachae and L. dumoffii.
Illness and treatment:
There are two clinically and epidemiologically distinct
illnesses: Legionnaires’ disease with fever, muscle
aches, cough, pneumonia; and Pontiac fever, a milder
illness without pneumonia. Treatment is with antibiotics.
Sources:
The organism is ubiquitous.
Hot water systems (showers), air conditioning cooling
towers, evaporative condensers, humidifiers, whirlpool spas,
respiratory therapy devices, decorative fountains, and
potting soil have been implicated epidemiologically in
outbreaks.
Additional risks:
Illness is more common with age over 65 years, smoking,
diabetes, chronic lung disease, or immunosuppression
(particularly due to corticosteroids or organ transplant).
Prevention:
Maintain cooling towers properly. Do not use tap water in
respiratory therapy devices.
Recent Washington trends:
Each year there are fewer than 30 reports, with one to 4
deaths.
2008:
19 cases (0.3 cases/100,000
population) were reported with one death. Ages ranged from
25 to 82 years (median 62 years). Of 18 patients with risk
factor data, 14 (78%) reported as least one of the following
risk factors: chronic liver disease, immunosuppressive
therapy, chronic diabetes, chronic lung disease, or smoking.
Purpose of Reporting and
Surveillance
- To identify sources of
transmission (e.g., contaminated water source) and prevent
further transmission from such a source.
- To identify outbreaks and educate potentially exposed
persons about signs and symptoms of disease, thereby
facilitating early diagnosis and
treatment.
Legal Reporting Requirements
-
Health care providers: notifiable to
local health jurisdiction within 3 work days
-
Hospitals: notifiable to local health
jurisdiction within 3 work days
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Laboratories: no requirements for
reporting; specimen submission is not required
-
Local health
jurisdictions: notifiable to the Washington State
Department of Health (DOH) Communicable Disease
Epidemiology Section (CDES) within 7 days of case
investigation completion or summary information required
within 21 days
Last
update
November 2009 |
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