Published Date: 2006-06-16 00:00:00
Subject: PRO/EDR> Norovirus, cruise ships - Europe
Archive Number: 20060616.1670
NOROVIRUS, CRUISE SHIPS - EUROPE
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: 15 Jun 2006
From: ProMED-mail <email@example.com>
Source: Eurosurveillance Weekly release, Vol.11 Iss.6 [edited]
European Centre for Disease Prevention and Control, Stockholm, Sweden
Seven recent or ongoing outbreaks of norovirus infection on cruise ships
have been reported in various media, and several have been posted in
ProMED-mail . DIVINE-NET, the European network for the prevention of
emerging (food-borne) enteric viral infections
launched a European investigation, in collaboration with the European
Centre for Disease Prevention and Control (ECDC).
Between 24 Apr and 9 Jun 2006, 4 cruise ships each reported one on-board
outbreak of gastroenteritis, and 3 ships each reported 2 outbreaks to the
appropriate health authorities. Infection was confirmed in 2 ships after
samples tested positive for norovirus; other samples are still being
tested. Based on the current information, it appears that the 7 ships are
owned by 5 different companies. Most of the ships have been operating in
the Baltic sea.
DIVINE-NET has sent a request for information to its focal points in the 13
European countries that participate in the network, providing the travel
routes of the involved ships and requesting additional information. By 14
Jun, there was no indication of a common factor linking these outbreaks.
The European Commission issued an alert to European Union member states via
the European Early Warning and Surveillance System on 15 Jun.
Norovirus outbreaks are a well-known problem on cruise ships, and ship
operating companies have guidelines for sanitation procedures. Despite
implementing thorough disinfection measures, outbreaks tend to continue on
consecutive cruises . Because norovirus is highly contagious and can be
spread via several different routes, including person-to-person, food,
water and environmental contamination, the ships provide an excellent
environment for the virus to spread rapidly . The outbreak
investigations are usually performed by local health authorities in
collaboration with ship operating companies. However, it is not always
clear who should be in charge of investigations and to what extent the
local authorities can collect confidential information, especially if the
ships are in international waters. As the ships visit several cities in
various countries, the actions taken in one country may not be readily
informed to the authorities in other countries.
Although the norovirus outbreaks occur regularly on cruise ships, the 7
events in a relatively short time period raise questions on possible common
links between the outbreaks and underline a need for international
guidelines on outbreak investigations on cruise ships.
Information reported to DIVINE-NET on 13 Jun is presented below.
Information is not complete, but gives an idea of the extent of the outbreaks.
Ship A, The Netherlands
- Route: Zutphen (Netherlands) -Antwerp (Belgium)
- Cases: On 26 April 2006, an outbreak of gastroenteritis (15 cases) was
reported on a cruise ship chartered by a Japanese tour organisation. The
index patient became ill on 24 Apr. The ship left for Antwerp, Belgium on
- Samples: Swab samples were taken from door handles, toilets, and a
reception counter and found to be positive for norovirus. The sequences
were determined: GGII.4. A stool sample was collected from one of the
patients and tested negative for norovirus.
- Control measures taken: At the time of reporting some hygiene measures
had been taken. The ship was thoroughly cleaned before the arrival of a new
group of passengers. No new cases have been reported.
Ship B, The Netherlands
- Route: Kiel (Germany), Nijmegen (Netherlands), Vienna (Austria)
- Cases: On 22 May a general practitioner reported several cases of
norovirus infection to the Municipal Health Service in Nijmegen (eastern
Netherlands, on the Rhine and close to the border with Germany). No further
investigation was performed at that time.
- On 9 Jun new cases were reported from the ship B. Ship B was at that time
sailing towards Vienna.
- Samples: During the second outbreak, patient samples were collected in
Germany and sent to RIVM in Bilthoven for norovirus testing. No further
information available at this time.
Ship C, docked at Harwich (England, UK)
- Route: Harwich (UK), Bergen (Norway) , Flam (Norway), Gudangan (Norway),
Rosendal (Norway), Harwich.
- Cases: On 29 May, an outbreak of gastroenteritis was reported, thought to
be caused by norovirus. About 70 passengers and 15 crew members were
infected. Most of the passengers on ship C are from the United Kingdom. It
was reported that 2 passengers were ill when the ship departed from Bergen
- On 9 Jun, a 2nd outbreak was reported, affecting 28 people in a new group
of passengers. Bergen in Norway was visited during this trip.
- Samples: During the 1st outbreak, stool samples from passengers were
examined to look for norovirus at a laboratory in Trondheim, Norway. Due to
miscommunication, no patient or environmental samples were taken during the
- Food supply: Both trips included an excursion to a fish market [where?],
where passengers ate various fish and shellfish. Therefore this market is a
potential source of infection.
Ship D, Nijmegen (The Netherlands)
- Route: Kiel (Germany) - Nijmegen (Netherlands) - Vienna (Austria)
- Cases: On 30 May, a cruise ship reported 61 cases of gastroenteritis in a
group of American passengers. The index case had illness onset on 20 May,
and the last reported case had illness onset on 30 May. There was a peak of
15 new cases on 28 May. MHS Nijmegen and the VWA (Dutch Food Safety
Authority) visited the ship for further investigation.
- During ship D's previous trip, it was reported that a small number of
gastroenteritis cases occurred. According to the ship's captain, some of
the passengers mentioned having had the same symptoms before boarding the
ship. However, this was not confirmed by a medical doctor.
- Both ship B and ship D are owned by the same company. However, none of
the crew members had worked on both ships.
- Samples: Six patient samples were collected. Stool samples from 2
patients tested positive for norovirus; testing of samples from a further 4
patients is still in progress. Environmental swab samples tested positive,
and sequences from swabs, patients and other cruise ships will be compared.
- Food supply: ship B and D were both supplied with food in Kiel, by a
company that may supply other cruise ships. Fresh food was purchased
locally. It is unclear whether high-risk foods such as shellfish and soft
fruit were included in this local purchase.
Ship E, docked at Southampton, (England, UK)
- Route: Vigo (Spain), Southampton (UK)
- Illness reported 30 May
- Arrival from Vigo, Spain. It is not known whether there were any stops
between Vigo and Southampton.
- Dealt with by Southampton and Spain.
- No further information currently available
Ship F, docked at Dundee (Scotland, UK)
- Route: Tallinn (Estonia), Copenhagen (Denmark), Stockholm (Sweden),
Helsinki (Finland), St Petersburg (Russia)
- Cases: on 29 May a first outbreak was reported in Dundee.
- On 9 Jun, a second outbreak was reported in Hull
- In one of the outbreaks, 70 passengers and 15 crew members were affected.
It is not known whether passengers brought the virus onto the ship or
whether the outbreak is linked to its sister ship, ship C, which is owned
by the same company. Ship F did not visit Bergen.
- No further information currently available
Ship G, docked at Leith (Scotland, UK)
- On 12 Jun an outbreak was reported with 116 cases.
- This ship is owned by a different company.
- No further information is currently available.
J Harris (DIVINE-NET)
2. Centers for Disease Control and Prevention (CDC). Outbreaks of
Gastroenteritis Associated with Noroviruses on Cruise Ships --- United
States, 2002. MMWR Morb Mortal Wkly Rep. 2002 Dec 13;51(49):1112-5.
3. Isakbaeva ET, Widdowson MA, Beard RS, Bulens SN, Mullins J, Monroe SS,
et al. Norovirus Transmission on Cruise Ship. Emerg Infect Dis. 2005
[Byline: J Takkinen <Johanna.Takkinen@ecdc.eu.int>]
[We are trying to cut down on reports of norovirus outbreaks on cruise
ships, as there are so many, but this is a particularly good summary of
outbreaks on European cruises in 2006, and in Europe rather than the USA &
Caribbean, as in the past. - Mod.JW]