This increase also has been noted by other authors. Community or hospital outbreaks also produce variations in the incidence of Legionnaires’ disease. In one prospective study of community-acquired pneumonia requiring hospitalization carried out between 1985 and 1986 in our city, the incidence of pneumonia due to L pneumophila was 14.2 percent (32 of 226 cases), but the authors included data from 17 patients who were admitted during an outbreak. In our hospital, the actual incidence is 7 percent but no outbreak was detected during the period of study, so we can consider that this incidence reflects the role of L pneumophila as the causal agent of community-acquired pneumonia in our city.
Although males are affected more often than females, it is quite surprising that all patients in our series were males. History of smoking or alcoholism or both is frequent in patients with Legionnaires’ disease, data that we also have observed.
Pneumonia caused by L pneumophila usually affects people with an underlying disease and it was present in more than two thirds of our patients. Among our patients with underlying disease, when heart failure was present, the mortality was higher.
Clinical and laboratory findings of Legionnaires’ disease have been widely studied and our data are quite similar to those already described.