Legionellosis fact sheet (Legionnaires' disease, Pontiac fever) [Apr. 2008]

Georgia Department of Human Resources (DHR) Division of Public Health
LEGIONELLOSIS FACT SHEET (Legionnaires' disease, Pontiac fever)
(updated April 2008)
Agents: Legionella pneumophila and other Legionella species.
Brief Description: Legionellosis has two clinically and epidemiologically distinct manifestations: Legionnaires' disease and Pontiac fever. Both illnesses are characterized by anorexia, malaise, myalgia, headache, and fever; however, Legionnaires' disease is associated with pneumonia, while Pontiac fever is a milder, non-pneumonic illness.
Reservoir: Primarily aqueous. Drinking water from approximately 30% of municipal water systems in the United States will grow Legionella when cultured. Legionella-containing water that has been aerosolized by showers, air-conditioning cooling towers, evaporative condensers, humidifiers, respiratory therapy devices, whirlpool spas and decorative fountains have been implicated epidemiologically during outbreaks. There is evidence to suggest that locations in which the municipal water system is disinfected with monochloramine are less likely to have outbreaks of legionellosis. The organism has also been isolated from environmental sources such as water in creeks and ponds and soil along their banks. Potting soil has also been implicated as a source of Legionella in human cases of Legionnaires' disease.
Mode of Transmission: Transmission is by inhalation of contaminated aerosols; person-to-person transmission does not occur. Outbreaks occur when two or more people develop symptoms after exposure to the same source.
Risk Groups: Illness occurs most frequently among the elderly, cigarette smokers, persons with
chronic lung or immunocompromising disease, and persons receiving immunosuppressive drugs.
Incubation Period: For Legionnaires' disease: 2 to 10 days, most often 5 to 6 days. For Pontiac fever: 566 hours, most often 24-48 hours.
Diagnostic Testing: Culture Referral 1. Specimen: Pure Culture 2. Outfits: (culture referral) 3. Lab Form: 3410 4. Lab Test Performed: Culture identification, confirmation, and/or serotyping 5. Lab: Bacteriology, Georgia Public Health Laboratory (GPHL) and CDC NOTE: All isolates from human cases may be forwarded to GPHL for confirmation & identification. GPHL will forward to CDC for serotyping.
Treatment: Erythromycin is the drug of choice. Clarithromycin and azithromycin may be effective. Rifampin may be a valuable adjunct but should not be used alone.
Investigation: Patient interview should focus on potential sources of infection, particularly related to common areas. A thorough travel history is required. Determine if other cases have occurred, indicating the possibility of a common source outbreak.
Epidemiology Section 2 Peachtree Street NW 14th Floor Atlanta, Georgia 30303-3142
http://health.state.ga.us/

Georgia Department of Human Resources (DHR) Division of Public Health

Case Classification:

Legionellosis

Clinical Criteria: a.) Legionnaires' disease: fever, myalgia, cough, and clinical or radiographic

pneumonia, or b.) Pontiac fever: a milder illness without pneumonia.

Confirmed

Suspect

A confirmed case meets the clinical

A suspect case meets the clinical criteria and the following

criteria and the following laboratory

laboratory criteria:

criteria:

Fourfold or greater rise in antibody titer to specific

Detection of Legionella pneumophila

species or serogroups of Legionella other than L.

serogroup 1 antigen in urine using

pneumophila serogroup 1 (e.g., L. micdadei, L.

validated reagents, or

pneumophila serogroup 6), or

Isolation of any Legionella organism Fourfold or greater rise in antibody titer to multiple

from respiratory secretions, lung

species of Legionella using pooled antigen and validated

tissue, pleural fluid, or other
normally sterile fluid, or Fourfold or greater rise in specific

reagent, or Detection of specific Legionella antigen or staining of the
organism in respiratory secretions, lung tissue, or pleural

serum antibody titer to Legionella

fluid by direct fluorescent antibody (DFA) staining,

pneumophila serogroup 1 using

immunohistochemstry (IHC), or other similar method,

validated reagents.

using validated reagents, or Detection of Legionella species by a validated nucleic

acid assay.

Reporting: Report cases WITHIN 7 DAYS to the local health department, District Health Office, or the Epidemiology Section electronically through the State Electronic Notifiable Disease Surveillance System (SENDSS) at http://sendss.state.ga.us, or complete and mail CDC Form 52.56 (revised Aug. 1999), Legionellosis Case Report http://www.health.state.ga.us/pdfs/epi/notifiable/legionella.crf.02.pdf for each reported case.

Reported Cases of Legionellosis in Georgia, 1993-2007

Year

Number of Cases

1993

35

1994

118

1995

19

1996

3

1997

6

1998

8

1999

5

2000

10

2001

12

2002

19

2003

35

2004

43

2005

39

2006

38

2007

43

Epidemiology Section 2 Peachtree Street NW 14th Floor Atlanta, Georgia 30303-3142
http://health.state.ga.us/

Georgia Department of Human Resources (DHR) Division of Public Health
References: 1. Aspen Reference Group. Legionellosis (Legionnaires' Disease) In: Infectious Disease Resource
Manual. Nell Di Lima S, and Eutsey D, Eds. Aspen Publishers, Inc. 1999: p. 3:73.
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2. Beneneson, A, ed. In: Control of Communicable Diseases Manual. 16 ed. Washington, DC: American Public Health Association, 1995: pp. 256-258.
3. Centers for Disease Control and Prevention. Legionellosis 2005 Case Definition. http://www.cdc.gov/ncphi/disss/nndss/casedef/legionellosis_current.htm.
4. Centers for Disease Control and Prevention. Sustained Transmission of Nosocomial Legionnaires Disease -- Arizona and Ohio. MMWR 1997; 46(19): 416-421.
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5. Chin J, ed. Legionellosis. In: Control of Communicable Diseases Manual. 17 ed. Washington, DC: American Public Health Association, 2000: pp. 281-283.
Links:
CDC Legionellosis Fact Sheet-www.cdc.gov/ncidod/dbmd/diseaseinfo/legionellosis_g.htm.
Epidemiology Section 2 Peachtree Street NW 14th Floor Atlanta, Georgia 30303-3142
http://health.state.ga.us/