Additional value of typing Noroviruses in gastroenteritis outbreaks in Amsterdam, The Netherlands

Abstract 

Background

In Amsterdam, 17 of the 55 gastroenteritis (GI) outbreaks reported from January 2002 to May 2003 were confirmed to be caused by noroviruses (NV).

Objective

In this study, we describe the molecular epidemiology of a group of nine outbreaks associated with a catering firm and two outbreaks, 5 months apart, in an Amsterdam hospital. All outbreaks were typed to confirm their linkage, and the hospital-related cases were studied to see if the two outbreaks were caused by one persisting NV strain or by a reintroduction after 5 months.

Results and conclusions

For the outbreaks associated with the catering firm one NV genogroup I strain was found which was identical in sequence among customers and employees of the caterer. This was not the strain that predominantly circulated in 2002/2003 in and around Amsterdam, which was the NV genogroup II4 “new variant” (GgII4nv) strain. In the Amsterdam hospital, the two outbreaks were caused by this predominant GgII4nv type, and we argue that NV was most likely reintroduced in the second outbreak from the Amsterdam community.

Abbreviations: NV, norovirus, GgII4nv, genogroup II4 “new variant”, MHS, Municipal Health Service, AMHL, Amsterdam Municipal Health laboratory, RT-PCr, reverse transcriptase polymerase chain reaction, nt, nucleotides, pt, patient, emp, employee, cust, customer

Keywords: Norovirus, Outbreak, Genotyping, Molecular epidemiology