Published Date: 2006-07-06 00:00:00
Subject: PRO/EDR> Norovirus, cruise ships - Europe (02)
Archive Number: 20060706.1857
NOROVIRUS, CRUISE SHIPS - EUROPE (02)
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Thu 6 Jul 2006
From: ProMED-mail <firstname.lastname@example.org>
Source: Eurosurveillance weekly releases 2006, Volume 11 / Issue 7,
Thu 6 Jul 2006 [edited]
The European investigation into norovirus infection outbreaks on
cruise ships, carried out by DIVINE-NET, the European network for the
prevention of emerging (food-borne) enteric viral infections
continuing. By 5 Jul 2006, a total of 35 outbreaks of
gastrointestinal infection had been reported on 13 cruise ships
travelling around Europe. Norovirus (NoV) has been confirmed as the
aetiological agent for outbreaks on 9 of the 13 ships. A total of
1088 cases have been reported, of which at least 642 (59 percent) are
known to have been in passengers and 64 (6 percent) in crew members.
The most recent suspected outbreak was reported on 5 Jul 2006.
The investigation has focused on 2 main hypotheses:
(1) The introduction of NoV on the ships from a common source (food
or water supply); and
(2) The circulation of NoV on cruise ships as a reflection of illness
in the community, possibly increased due to circulation of new variant strains.
Of the 13 ships involved, 9 have reported consecutive outbreak
episodes, ranging from 2 to 5. Samples to confirm the diagnosis have
not been collected consistently in consecutive outbreaks, but the
data suggest persistence of NoV on ships. Alternatively, new
passengers may reintroduce the virus, precipitating new outbreaks.
The virological investigation has shown that the confirmed outbreaks
are caused by 2 new variant GGII4 NoV strains. An open access strain
matching system has been established to allow harmonised sequence
comparisons worldwide for commonly used genome regions
(<http://www.rivm.nl/bnwww>, follow the links to 'Foodborne viruses
in Europe' and 'quick typing database'). Requests for strain
comparison can also be sent to <email@example.com>.
A survey is ongoing among DIVINE-NET members to provide background
levels of outbreak reporting in the community. A retrospective cohort
study and a detailed review of hygiene protocols are planned on the
ship where the most recent outbreak was reported. In addition,
guidelines on NoV control in different settings are being reviewed.
Based on the available information, and pending the completion of the
analysis of data, there is no indication that a common source event
introduced NoV on these ships. The most likely hypothesis is that
cruise ship outbreaks reflect increased levels of illness in the community.
(By M Koopmans1,2 (<Marion.Koopmans@rivm.nl>), J Harris2,3 L
Verhoef1,2, E Depoortere4, J Takkinen4, D Coulombier4. At the
1National Institute of Public Health (RIVM), Bilthoven,The
Netherlands,2DIVINE-NET,3Health Protection Agency Centre for
Infections, London, United Kingdom, and 4European Centre for Disease
Prevention and , on behalf of the international outbreak
investigation team Control, Stockholm, Sweden)
(1) Takkinen J. Recent norovirus outbreaks on river and seagoing
cruise ships in Europe. Euro Surveill 2006;11(6):E060615.2. Available from:
[This report comes to no definite conclusion regarding the particular
vulnerability of cruise ships to outbreaks of norovirus infection.
The open access strain matching system for food-borne virus in
Europe, however, is a welcome development which should resolve this
issue. Until data become available from this initiative, this thread
is now cut. - Mod.CP]