Intensieve surveillance van Shigatoxine-producerende Escherichia coli O157 in Nederland, 2005

Since January 1999, an enhanced surveillance of Shiga toxin-producing Escherichia coli (STEC) O157 has been implemented in the Netherlands. In 2005, 53 symptomatic patients were diagnosed with STEC O157. This was relatively high compared with the number in previous years (annually 36 to 57), due to a national outbreak with 21 patients involved. Of the patients, 33% were hospitalised, 8% developed the haemolytic-uraemic syndrome (exclusion of outbreak-cases: 13%), including one one-year-old boy who died. Consumption of raw or undercooked beef and contact with farm animals and manure are still most frequently mentioned by the patients as possible cause. In 2005, cluster analyses of the fingerprints of bacterial DNA from the STEC O157 isolates (by pulsed-field gel electrophoresis) nine times suggested a relationship between several patients. For three clusters this was supported by additional epidemiological information. One cluster, consisting of two sub clusters, comprises the national outbreak caused by filet americain, except for two patients who fell ill two and one month before this outbreak. Furthermore, one household cluster was identified for which an indistinguishable PFGE pattern was found in a manure isolate taken from their cattle. In addition, an isolate from one individual case could be matched with an isolate taken from their neighbours cattle. As other serogroups than O157 can cause serious illness, a collaboration between RIVM and eight medical microbiological laboratories to assess the relative importance of non-O157 serogroups was started in the Netherlands in the autumn of 2005.