[Survey of Legionella in the Parisian environment. Practical implications]

A qualitative and quantitative survey of environmental Legionella in the Paris area was undertaken because of its epidemiological implications. Over a 2-year period, 322 water samples from the Paris area (unrelated to a legionnaires' disease outbreak) were examined for the presence of Legionella. No Legionella strain was isolated from the main water supplies of the municipality or from the distribution entry points of 36 buildings. Inside buildings, however, 84/190 (44.2%) tap water samples yielded one or several strains of Legionella (10(2) to 10(6) CFU/l). Contamination was significantly more frequent in hot tap water than in cold tap water. Legionella was isolated from 11 out of 14 air-conditioning systems investigated. Sixty-four of the 132 strains isolated were L. pneumophila serogroup 1. Other strains were L. pneumophila serogroups 2 to 6 (including a serogroup 4-5 variant), L. longbeachae serogroup 2 and 6 atypical Legionella.