Een epidemie van gastro-enteritis door een Norwalk-achtig virus na twee bruiloften in een restaurant; een pleidooi voor integraal microbiologisch onderzoek

To elucidate the cause of an epidemic of gastroenteritis amongst the guests and waiting staff of two weddings celebrated on the same day in the same restaurant.

Design

Retrospective and descriptive.

Method

Following an outbreak of gastroenteritis amongst 215 wedding guests and restaurant staff in 1999, the Public Health Institute Midden-Limburg, the Netherlands, inventoried the demographic and clinical variables and consumed foods by means of a structured written interview. Faecal samples and remaining food products were bacteriologically examined, and later on faeces were virologically examined for the presence of the Norwalk-like virus (NLV). The attack rates and the incidence rates of NLV-positive faecal specimens amongst consumers and non-consumers of specific food products were calculated, as well as the corresponding relative risks with 95 confidence intervals.

Results

The overall attack rate was 66. An NLV with the same genotype was found statistically significantly more frequently in faecal specimens of ill persons compared with non-ill individuals. Of the 61 different dishes served, two showed a statistically significant relation with being ill. These food products were eaten by 26 of the ill persons. No statistically significant association was found between NLV-positive faeces and consumption of a specific dish. The index case began having symptoms of gastroenteritis at the morning of the wedding party, before food was served. The guests of the two wedding parties used the same entrance and toilets.

Conclusion

The epidemic was caused by a single NLV strain. No association could be found between the consumption of certain food products and being ill. The NLV epidemic was probably caused through direct or indirect contact between wedding guests and restaurant personnel. In the case of such reports of gastroenteritis epidemics, it is strongly recommended to test faecal, food product and environment samples for both bacteria and viruses, with an emphasis on NLV, to ensure early diagnosis.