Psittacosis in a highly endemic area in Italy.

In one locality in Italy where the incidence of psittacosis has increased rapidly since 1980, a hospital-based study and a seroepidemiological survey were carried out in order to define the clinical and epidemiological features of psittacosis in that area. Registers of the Virology Unit of the University of Ancona, Italy, were reviewed and all hospitalized patients with a serological diagnosis of psittacosis were identified. A total of 76 cases were found and studied. A presumptive bird source was identified in 80% of 62 patients, on whom a detailed investigation had been possible. Poultry represented the most frequent probable source of infection. Clinically, the predominant pattern of illness was a moderately severe lower respiratory tract infection, with chest X-rays showing pulmonary shadowings in 68 patients (89%). In the seroepidemiological study, 51 out of 143 subjects were exposed to birds (35.7%), but only 7 out of 96 urban adult blood donors (7.3%) were positive for chlamydial antibodies using the microimmunofluorescence test.