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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.
2010:
35 cases (0.5 cases/100,000 population) were reported with 4 deaths; 15 (43%) were
admitted to intensive care units and 11 (31%) required ventilation. Median age was
61 years (range 28-89) and 26 (74%) reported at least one of the following risk factors:
chronic liver disease, immunosuppressive therapy, chronic diabetes, chronic lung disease,
or smoking. Of cases with a species identified, 31 (89%) had L. pneumophila. 9 (26%)
were travel-associated with 3 cases reporting travel to Mexico.
Purpose of Reporting and Surveillance
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To identify sources of transmission (e.g., contaminated water source) and prevent
further transmission from such a source
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To identify outbreaks and educate potentially exposed persons about signs and symptoms of disease, thereby
facilitating early diagnosis and treatment
Legal Reporting Requirements
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Health care providers:
notifiable to local health jurisdiction within 24 hours
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Health care facilities:
notifiable to local health jurisdiction within 24 hours
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Laboratories:
Legionella species notifiable to local health jurisdiction within 24 hours; specimen
submission is required – culture (2 business days)
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Local health jurisdictions:
notifiable to the Washington State Department of Health (DOH) Communicable Disease Epidemiology (CDE)
within 7 days of case investigation completion or summary information required within 21 days
Last update
December 2011 |
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