Legionella pneumophila serogroup 3 prevalence in drinking water survey in Israel (2003–2007)

A 5-year survey (2003 to 2007) was carried out on various drinking water sources in Israel for detection of Legionella spp. The most frequently isolated species was L. pneumophila serogroup 3 (prevalence 60.44±5.6) followed by L. pneumophila serogroup 1 (26.98±5.2) and other serogroups and unidentified species (12.6±9.8). L. pneumophila serogroup 1 is the worldwide prevalent serogroup in water sources while serogroup 3 was only occasionally reported. Previous reports on L. pneumophila serogroup 1 as the main causative of respiratory disease in Israel revealed a drop from 52 to 15% in incidence during a 5-year survey, with a rise in the incidence of seropositivity to “other Legionellae”, mainly sg. 3. As antigenuria is the main clinical tool to detect Legionellosis among infected patients, the shift from serogroup 1 to serogroup 3 in water sources will go undetected for obvious reasons. The process of serogroups prevalence shift in water sources is an interesting issue that has to be investigated further in order to advance our understanding of Legionella epidemiology.