[The epidemiology of human enterohemorrhagic Escherichia coli infections in Lower Saxony]

Abstract

Background: In the German federal state Lower Saxony, data on infections with enterohemorrhagic Escherichia coli (EHEC) and hemolytic uremic syndrome (HUS) are collected systematically since 1997 based on reports by physicians and laboratories. Initially the data were collected by means of a specific established surveillance system, since 2001 they are collected as part of the new infectious disease law.

Results: From 1997 to 2003, in Lower Saxony 880 EHEC-infections and 112 HUS-cases, 6 of whom died, were notified. This corresponds to an incidence of 1.6 EHEC-infections and 0.2 HUS-cases per 100000 person-years. No secular trend was observ-ed for the yearly number of HUS-cases, but raised numbers were observed for the years 1997 and 2002. There were strong regional differences of the EHEC/HUS-incidence from 0.7 in the district Braunschweig to 3.5 in the district Weser-Ems. For 56% of reported EHEC-cases, serotype information was available. The most frequent serogroup was O157, accounting for 30% of cases with serotype information. Of HUS-cases with known serotype, 86% were caused by O157, 20% by O157:H-. 52% of the EHEC-cases were less than 5 years old (HUS: 77%), and 68% less than 10 years (HUS: 92%). 23% of EHEC/HUS-cases could be identified as part of clusters with a mean number of 2.6 cases per cluster. These clusters almost exclusively affect-ed families. Though the data also contained information on possible sources or routes of infection, for none of the cases a microbiologically assured source was documented.

Conclusions: The incidences of EHEC and HUS were higher in Lower-Saxony than in the whole of Germany. During the study period no significant trends concerning the number of HUS-cases or the distribution of serotypes were observed. More frequent serotyping and more complete information on sources or risks of infection should be achieved.