Legionellosis (Legionella species)

Clinical criteria
Legionnaires’ disease
Any person with pneumonia
Pontiac fever
A self limiting influenza like illness characterised by fever, headache, myalgia and non-productive cough. Patients recover spontaneously without therapy after 2-5 days. No signs of pneumonia. Pontiac fever is frequently associated with Legionnaires’ disease outbreaks.

Laboratory criteria
– Laboratory criteria for case confirmation

At least one of the following three:
– Isolation of Legionella spp. from respiratory secretions or any normally sterile site
– Detection of Legionella pneumophila antigen in urine
– Significant rise in specific antibody level to Legionella pneumophila serogroup 1 in paired serum samples

– Laboratory criteria for a probable case

At least one of the following four:
– Detection of Legionella pneumophila antigen in respiratory secretions or lung tissue e.g. by DFA staining using monoclonal-antibody derived reagents
– Detection of Legionella spp. nucleic acid in respiratory secretions, lung tissue or any normally sterile site
– Significant rise in specific antibody level to Legionella pneumophila other than serogroup 1, or other Legionella spp. in paired serum samples
– Single high level of specific antibody to Legionella pneumophila serogroup 1 in serum

Epidemiological criteria
NA

Case classification
A. Possible case
NA
B. Probable case
Any person meeting either of the clinical criteria AND at least one laboratory criterion for a probable case
C. Confirmed case
Any person meeting either of the clinical criteria AND at least one laboratory criterion for a confirmed case 

Current as of: 22 January 2019