Potable water as a source for legionellosis.

Abstract

Several lines of evidence have been examined in attempts to implicate potable water as a source for legionellosis. Success has been mixed. The strongest evidence has been the similarity of strains recovered from patients and from potable water and the cessation of outbreaks following institution of measures to eradicate Legionella from potable water systems. Epidemiologic efforts to identify the effective mode of exposure to water (e.g. ingestion) have been remarkably unsuccessful. Although L pneumophila can clearly be acquired on occasion from potable water, the proportion of cases traceable to this source is unknown, as is the role of potable water as a source of infection by other Legionellae. Hyperchlorination, raising hot water temperatures to greater than 55 degrees C, and replacing rubber gaskets are useful methods for controlling outbreaks of legionellosis traced to potable water systems but are not yet justified as routine preventative methods in the absence of such an outbreak.

Legionnaires disease: historical perspective.

“…The evidence for cooling towers and evaporative condensers (185) and potable water (99) has been recently reviewed.…”

“…Because of the ubiquity of legionellae in the environment, the lack of association of most isolates with human disease, and the adverse effects on humans or the environment of procedures designed to eliminate the bacteria (99), it seems most prudent to concentrate scarce resources on reliable documentation of human infection. Once human disease has been found, all possible environmental sources should be examined, using the assistance of molecular biology for the typing of isolates.…”

Genetic, immunological, and cytotoxic comparisons of Legionella proteolytic activities

“…The majority (85 to 90%) of human pneumonic infections attributed to Legioniella species have been caused by Legionella pnieimophila serogroup pneiumophila (30), L. ,nicdadei (21), and Legionella feeleii (24). It is likely that a combination of risk factors resulting in decreased host defenses and exposure to an environmental source produces the highest probability of infection (1,(15)(16)(17). However, the genetic basis for virulence of these organisms remains unknown.…”