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Home Eurosurveillance Weekly Release  2006: Volume 11/ Issue 42 Article 2
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Eurosurveillance, Volume 11, Issue 42, 18 October 2006

Citation style for this article: Depoortere E, Takkinen J, ECDC Norovirus expert group. Coordinated European actions to prevent and control norovirus outbreaks on cruise ships. Euro Surveill. 2006;11(42):pii=3066. Available online:

Coordinated European actions to prevent and control norovirus outbreaks on cruise ships

E Depoortere1, J Takkinen1 (, on behalf of the ECDC Norovirus expert group*

European Centre for Disease Prevention and Control, Stockholm, Sweden

*EH Cramer, E Dahl, I Friesema, C Hatjichristodoulou, M Koopmans, J Kremastinou-Kourea, M Kuusi, P McKeown, P Pothier, J van Steenbergen, B Suski

Between 1 January and 5 July 2006, 42 reported outbreaks of gastroenteritis on 13 different cruise ships sailing in European waters were confirmed or suspected to be caused by norovirus. Almost 1500 cases of gastroenteritis were reported among passengers and crew, but no common source has been determined. Two new norovirus variants were identified through the microbiological analysis of patient and environmental samples during these outbreaks. Based on previous years’ experience, an ECDC expert panel considered it likely that the emergence of new norovirus strains coincided with increased reports of outbreaks in European countries, which was reflected by increased activity on cruise ships [1]. Investigations of these outbreaks were carried out by national authorities, coordinated by the European Union funded surveillance network DIVINE-NET (, in collaboration with the European Centre for Disease Prevention and Control (ECDC) [2].

Responsibility for investigation of norovirus outbreaks with international implications, which include those in a relatively closed setting such as on cruise ships, trains, and aeroplanes that travel across national borders, is currently ill-defined at present. These recent outbreaks illustrate the need for European-level coordination.

The ECDC expert panel, with expertise in the fields of norovirus epidemiology and microbiology, including experts from the EU funded project SHIPSAN (‘ship sanitation programme’ and the CDC Vessel Sanitation Programme (VSP), recently met with the following objectives:

• to review current norovirus epidemiology in Europe to assess the actions needed to prevent and control future outbreaks in cruise ships
• to review the existing guidelines for prevention and control measures in cruise ships and other public settings

Need for guidance and legal framework identified

Several challenges were identified with relation to the current norovirus prevention and control strategies:

  • There is a clear need to develop a common approach concerning the identification and investigation of norovirus outbreaks on cruise ships, in order to ensure comparable data collection, identification of a potential source (food, water, person) and timely actions to be taken to cease the spread of infection and prevent outbreaks recurring on the same ship. The definition of an outbreak should be agreed upon, which can trigger an outbreak investigation that is based on a generic protocol.
  • Practical European guidelines concerning cleaning, disinfection and food safety would be useful for preventing and controlling norovirus and also outbreaks due to other pathogens on ships. Because norovirus is particularly resistant in the environment, control measures must be norovirus-specific.
  • There is a need for standard sanitary inspection procedures based on the Hazard Analysis Critical Control Points (HACCP) concept on cruise ships.
  • Considering the number of parties involved, legal responsibilities of each European country and the industry regarding the outbreak investigation and response must be clarified.

Some of these challenges will be addressed by SHIPSAN, which has the following objectives:

  • To describe the current situation on ship sanitation and control of communicable diseases related to cruise ships and ferries in the EU
  • To assess the usefulness of an EU ship sanitation strategy
  • To enhance the EU capacity to prevent outbreaks and control communicable diseases on cruise ships and ferries

Actions being taken
The panel concluded that practical and standardised guidelines for the implementation of prevention and control measures, based on best practices identified from previous experience, should be developed. The cruise ship industry has a major interest in limiting and containing norovirus outbreaks, so there is an opportunity for a close and mutually beneficial collaboration between public health authorities and industry. An exploratory meeting with the medical directors of the major ship-owning companies will be organised by ECDC.

The main partners following up the meeting’s recommendations will be members of SHIPSAN, the Vessel Sanitation Program of the United States Centers for Disease Control and Prevention [3], DIVINE-NET, the European Commission, and the ship owning companies.

The full report of the ECDC expert panel meeting which took place on 12 September 2006 is available on the ECDC website (

  1. Lopman B, Vennema H, Kohli E, Pothier P, Sanchez A, Negredo A, et al.. Increase in viral gastroenteritis outbreaks in Europe and epidemic spread of new norovirus variant. Lancet 2004; 363: 682-8.
  2. Koopmans M, Harris J, Verhoef L, Depoortere E, Takkinen J, Coulombier D; International Outbreak Investigation Team. European investigation into recent norovirus outbreaks on cruise ships: update. Euro Surveill 2006; 11(7) E060706.5 (
  3. Vessel Sanitation Program. Centers for Disease Control and Prevention website. ( [accessed 16 October 2006]

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