[Levels of anti-Legionella antibodies in a healthy Neapolitan population].

Legionella pneumophila was firstly recognized as the causative agent of a serious pneumonia about a decade ago. Since then a number of studies was carried out in order to define the epidemiological and clinical features of the microorganism. So far a high variability of the geographic distribution of the infection has been reported, with prevalences up to 50% of healthy populations. Therefore, a seroepidemiological survey was carried out on prevalence of Legionella pneumophila infections among healthy people in Naples. 562 serum specimens were randomly collected and examined by the indirect fluorescent antibody technique for antibodies against serogroups 1 to 6 of Legionella pneumophila, using 1:256 as the cut off titer. An overall prevalence of 23% was observed among the 562 persons tested. 24.5% among males and 21.9% among females had antibodies against Legionella pneumophila. There were no significant differences associated with sex and age, even though an apparent increase with age was observed. The highest prevalence was found for antibodies against serogroup 3 (9.4%). This finding was confirmed in all the age-sex groups, but among males aging between 21 and 40 years and among elderly people, 12.1% of persons tested had antibodies against only one serogroup of Legionella pneumophila, whilst 5.3%, 3.4% and 2.1% of subjects had antibodies against 2, 3 and 4 serogroups respectively. No serologic cross reactivity of Legionella pneumophila groups was found among seropositivities to different serogroups.