Shigatoxigenic Escherichia coli (STEC) infections in Finland during 1998-2002:: a population-based surveillance study

During 1998-2002, 124 microbiologically confirmed infections caused by shigatoxigenic Escherichia coli (STEC) were reported in Finland. Of these, 25 (20%) were associated with recent foreign travel. Temporal, geographical and type distribution of the domestically acquired infections (n = 99) caused by strains of serogroup O157 (n = 52) and non-O157 (n = 47) were analysed further. The median age of the patients was 6(.)8 years (range 0(.)2-73(.)1 years). Of the index cases within 26 families, 71% were < 5 years old. Family-related infections accounted for 49%, sporadic infections 39%, and 11% were associated with three clusters. Only strains of serogroup 0 157 carrying eae and Stx(2) or its variants caused separate clusters. The incidence of STEC infections was at its highest (0-64/100 000) in 1998. Since 1999 it has declined considerably (0(.)17/100 000 in 2002). STEC infections occurred in 14 hospital districts, mostly (28%) in the Helsinki region. However, the incidence was highest (10(.)3) in northwest Finland.