Viral Gastroenteritis Outbreaks in Europe, 1995-2000

Ben A. Lopman, Mark H. Reacher, Yvonne van Duijnhoven, François-Xavier Hanon, David Brown, Marion Koopmans, on behalf of the Foodborne Viruses in Europe Group


Emerging Infectious Diseases. 2003;9(1) 

In This Article

Abstract and Introduction

To gain understanding of surveillance and epidemiology of viral gastroenteritis outbreaks in Europe, we compiled data from 10 surveillance systems in the Foodborne Viruses in Europe network. Established surveillance systems found Norovirus to be responsible for >85% (N=3,714) of all nonbacterial outbreaks of gastroenteritis reported from 1995 to 2000. However, the absolute number and population-based rates of viral gastroenteritis outbreaks differed markedly among European surveillance systems. A wide range of estimates of the importance of foodborne transmission were also found. We review these differences within the context of the sources of outbreak surveillance information, clinical definitions, and structures of the outbreak surveillance systems.

Viral pathogens are the most common cause of gastroenteritis in industrialized countries[1,2]. Mead et al. have estimated that of the 38.6 million annual cases of gastroenteritis in the United States, 30.8 million (80%) are the result of viral infections[3]. Enteric viral pathogens include Rotovirus A, Astrovirus, adenovirus, and Sapovirus, but most viral gastroenteritis infections are caused by Norovirus (formerly Norwalk-like viruses)[1,2,3]. The use of molecular diagnostics including reverse-transcriptase polymerase chain reaction (RT-PCR) and antigen detecting enzyme immunoassays (EIA)[4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20] have changed researchers' understanding of the epidemiology of human Caliciviridae (including Norovirus and Sapovirus)[21]. For example, using RT-PCR assays, Pang et al. showed that caliciviruses were as common a cause of infection as rotaviruses among children <2 years of age[22].

In addition, many reports have established the importance of noroviruses as a cause of outbreaks of food- and waterborne illness[23,24,25,26,27,28], though estimates of the proportion of infection spread by these modes vary widely: from 14% in England and Wales[29] to <40% in the United States[7]. While person-to-person transmission is probably the mode of infection of most cases, food- and waterborne infections may be of particular importance since these outbreaks have the potential to involve large numbers of people and wide geographic areas and, perhaps, to introduce new variants to an area[30].

A research network to study foodborne viruses in Europe was recently funded by the European Union. Through this project, the participant institutes have networked their virologic and epidemiologic surveillance in order to detect transnational outbreaks, elucidate transmission routes, and make international comparisons of the epidemiology of viral gastroenteritis. We chose to study outbreaks rather than community cases because viral gastroenteritis is a very common infection[1]; therefore, enumeration of epidemics (or outbreaks) may be more practical and useful since individual cases are poorly reported[31]. International comparisons of surveillance data are difficult because criteria for effective surveillance customarily varies across borders[32].

The objective of this survey was to capture information on the structure of outbreak surveillance in each country (including sources of data and definitions employed) and to gain estimates of the frequency of outbreaks, as well as to compare the setting of outbreaks, the importance of foodborne transmission, and the use of characterization techniques. We present surveillance data from viral gastroenteritis outbreaks from 1995 to 2000 collected by participant European countries. These data provide baseline information for future harmonization and comparison efforts.