[Legionellosis in Israel--a view of the situation]

Infection with Legionella remains an important cause of disease and death. We analyzed our laboratory data from 1993 through 1997, augmented by our 20 years of experience. The incidence of Legionella as a cause of pneumonia varied in our study from 5%-9%, with a slight increase during the winter. Isolation of these microorganisms from different water sources was higher during the summer and ranged from 7%-70%. Special laboratory tests are necessary to diagnose the disease and monitor these bacteria in water samples. The serologic method--indirect immunofluorescent assay--for 41 serogroups of Legionella was the main diagnostic method used. Legionella sg. 1 was the most frequent cause of the disease, with an incidence of 52% in 1993, decreasing to 15% in 1997. An increase in the incidence of seropositivity to "other Legionellae" is characteristic for our country. No correlation was found between the incidence of isolation of a specific strain and exposure. However, it is well known that the disease is overtreated but underdiagnosed, which requires reversal. Larger studies of Legionella colonization in water supplies and in air are needed in order to establish the risk of infection. Water sources are presently under-studied, as are respiratory devices in hospitals, or they are not studied at all in Israel, such as in mist machines in supermarkets, in dental clinics, and in ships and airplanes.