Legionnaires' Disease in Non-Legionnaires

Abstract

Seventeen patients with illness resembling Legionnaires'' disease were evaluated for antibodies to the Legionnaires'' bacillus. Three patients were Legionnaires who developed pneumonia after attending the July 1976 convention. All three were seropositive (titers .gtoreq. 1:128) to the Legionnaires'' bacillus. None of the remaining 14 patients were Legionnaires. Five were seropositive and 9 seronegative (titers .gtoreq. 1:32). The seropositive patients had illnessess best explained by Legionnaires'' disease, whereas the seronegative patients had illnesses better explained by other diagnoses. This correlation between serology and clinical findings supports the specificity of the antibody test for Legionnaires'' disease. Of the 5 non-Legionnaire seropositive cases, 2 occurred before, and one 3 mo. after, the convention. The case histories of these 5 patients are presented. Disease generally involved the lungs, kidneys and the CNS. Although the pathogenesis of this multiple organ involvement is unclear, a possible explanation is the production of a toxin by the Legionnaires'' bacillus.