Legionella in Water: What Should Be Done?

Over 700 cases of legionellosis are reported to the Centers for Disease Control (CDC) each year, but these cases probably represent only a fraction of those actually occurring. Although outbreaks of legionellosis have received the greatest public attention and the most intensive study, evidence from hospital- and population-based studies suggests that most cases are sporadic or unassociated with recognized outbreaks.1-3Many features of these sporadic cases remain poorly defined, including the way infections are acquired. In this issue ofThe Journal, Stout et al4report isolation of the sameLegionellafrom two sporadic cases of legionellosis and from their household water supplies. Since legionellae have been isolated from water sources epidemiologically associated with outbreaks of human disease,5-11it is not surprising that some sporadic cases will have similar associations. It is important, however, that this observation not be overinterpreted. The roles of environmental cultures and decontamination procedures