Characteristics of reoffending accommodation sites in Europe with clusters of Legionnaires disease, 2003-2007.

Between 2003 and 2007, 21% (n=100/477) of accommodation sites linked to clusters of two or more cases of Legionnaires’ disease that were investigated by the European Surveillance Scheme for Travel-Associated Legionnaires’ Disease (EWGLINET) went on to be associated with at least one further case, despite reporting that satisfactory control measures had been implemented at the time the cluster was first detected. This paper examines these sites (termed reoffenders) in order to determine whether they share any characteristics that may have contributed to the reoffence. All investigations conducted at cluster sites between 2003 and 2007 were included in the analysis, giving a total of 615 investigations conducted at 477 sites. Every country that investigated more than three cluster sites had to deal with at least one reoffence, and one site reoffended five times. The cases involved in the cluster that stayed elsewhere during their incubation periods could be used to help assess the probability of exposure, and therefore the risk, posed by particular cluster sites. A more extensive investigation and control regime may be needed in some instances to better control the risk of Legionnaires’ disease at an accommodation site.