SURVEILLANCE FOR LEGIONNAIRES-DISEASE - RISK-FACTORS FOR MORBIDITY AND MORTALITY

Background: To augment available information about the epidemiology of legionnaires' disease, we analyzed data reported to the passive surve illance system at the Centers for Disease Control and Prevention, Atla nta, Ga, from 1980 through 1989. Methods: Risk of disease associated w ith specific demographic characteristics and health conditions was cal culated by comparing the surveillance group with the US population. Ri sk of death was calculated using multivariate logistic regression mode ls. Results: A diagnosis of legionnaires' disease was confirmed on the basis of clinical and laboratory criteria for 3254 patients. Disease rates did not vary by year, but were higher in the northern states and during the summer. Legionella pneumophila, serogroup 1, constituted 7 1.5% of fully identified isolates. This study confirmed previously ide ntified risk factors for legionnaires' disease. In addition, a markedl y elevated risk was identified for persons with acquired immunodeficie ncy syndrome (rate ratio, 41.9; 95% confidence interval, 12.9, 71.0), or hematologic malignancy (rate ratio, 22.4; 95% confidence interval, 19.0, 25.9). Likelihood of death was increased in patients who were el derly or male; those with hospital-acquired infection, renal disease, malignancy, or immunosuppression; and chose from whom L pneumophila, s erogroup 6, was isolated. Conclusions: Infection with Legionella remai ns an important cause of disease and death in the United States. Diagn osis and treatment of legionnaires' disease should be targeted at pati ents at increased risk for illness and complications due to Legionella infection. Diagnostic tests for legionnaires' disease based on specie s other than L pneumophila, serogroup 1, should be developed and teste d. Recommendations for prevention of legionnaires' disease should be f ocused on settings where there are persons at greatest risk for illnes s or serious outcome.