Rapid And On-Site Immunochromatographic Cassette Test For Detecting Legionella Pneumophila Antigen Contamination in Water

Legionnaires' disease, named after the outbreak in 1976 at the American Legion conventionin Philadelphia, is caused by Legionella pneumophila and is characterized as an acute febrile respiratory illness ranging in severity from mild illness to fatal pneumonia.1The disease occurs in both epidemic and endemic forms and sporadic cases are not easily differentiated from other respiratory infections by clinical symptoms. An estimated 25,000 to 100,000 cases of Legionella infection occur in the United States annually. The resulting mortality rate, ranging from 25% to 40%2, can be lowered if the disease is diagnosed rapidly and appropriate antimicrobial therapy is instituted early. Known risk factors include immunosuppression, cigarette smoking, alcohol consumption and concomitant pulmonary

disease.2 The young and the elderly are particularly susceptible.

Legionella pneumophila is responsible for 80-90% of reported cases of Legionella infection with serogroup 1 accounting for greater than 70% of all legionellosis.. Current methods for the laboratory detection of pneumonia caused by Legionella pneumophila require a respiratory specimen (e.g. expectorated sputum, bronchial washing, transtracheal aspirate, lung biopsy) or paired sera (acute and convalescent) for an accurate diagnosis. These techniques include Legionella culture, direct fluorescent antibody (DFA), DNA probe, and indirect fluorescent antibody (IFA). All of these rely on either obtaining an adequate

respiratory specimen for sufficient sensitivity, or collecting sera at a two to six week interval. Unfortunately, one of the presenting signs of patients with Legionnaires' disease is the relative lack of productive sputum. In many patients, this necessitates the use of an invasive

procedure to obtain a respiratory specimen. Diagnosis by serological techniques is usually retrospective in nature, and even then, patient compliance in obtaining the necessary specimen is poor.