CLINICAL DESCRIPTION

An acute bacterial disease with two currently recognized, distinct clinical and epidemiological manifestations: Legionnaires' disease, which is characterized by fever, myalgia, cough, pneumonia, and Pontiac fever, a milder illness without pneumonia. The incubation period for Legionnaires' disease is 2 to 10 days, most often 5 to 6 days; Pontiac Fever 5 to 66 hours, most often 24 to 48 hours. A single case of Pontiac fever is not reportable, however it should be investigated because Pontiac fever often occurs as an outbreak, which is reportable.

1. CONFIRMED
   A clinically compatible case AND:
   • Isolation of Legionella pneumophila from respiratory secretions, lung tissue, pleural fluid, or other normally sterile body fluids, OR

   • Demonstration of a fourfold or greater rise in the reciprocal immunofluorescence antibody (IFA) titer to greater than or equal to 128 against Legionella pneumophila serogroup 1 between paired acute- and convalescent-phase serum specimens, OR

   • Detection of Legionella pneumophila serogroup 1 in respiratory secretions, lung tissue, or pleural fluid by direct fluorescent antibody testing, OR

   • Demonstration of Legionella pneumophila serogroup 1 antigen in urine by radioimmunoassay or enzyme-linked immunosorbent assay.
     
     
2. PROBABLE
   
   Not used
   
   
3. POSSIBLE
   
   Not used
   
   

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