Confirmed Case

• A confirmed case of legionellosis is defined as a clinical illness [1] with laboratory confirmation of infection:
• isolation of Legionella sp. from respiratory secretions, lung tissue, pleural fluid, or other normally sterile fluids;
  OR
• a significant (e.g. fourfold or greater) rise in Legionella sp. IgG titre between acute and convalescent sera;
  OR
• seroconversion from non-reactive to IgG or IgM reactive or from IgM reactive to IgG reactive;
  OR
• demonstration of L. pneumophila antigen in urine;
  OR
• demonstration of Legionella spp. DNA by NAT from respiratory secretions, lung tissue, pleural fluid, or other normally sterile fluids.

Notes

1. Clinical illness is defined as two distinct illnesses: Legionnaires' disease, characterized by fever, myalgia, cough and pneumonia, and Pontiac fever, a milder illness without pneumonia.