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Eurosurveillance, Volume 8, Issue 52, 23 December 2004
Articles

Citation style for this article: Kroneman A, Vennema H, van Duijnhoven Y, Duizer E, Koopmans M. High number of norovirus outbreaks associated with a GGII.4 variant in the Netherlands and elsewhere: does this herald a worldwide increase?. Euro Surveill. 2004;8(52):pii=2606. Available online: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=2606
This is the last weekly issue of 2004 – Eurosurveillance will be back with regular weekly releases on Thursday 6 January 2005. From the Eurosurveillance editorial team in England and France, we wish all our readers a merry Christmas, a happy New Year, and a peaceful holiday.

High number of norovirus outbreaks associated with a GGII.4 variant in the Netherlands and elsewhere: does this herald a worldwide increase?

Annelies Kroneman, Harry Vennema, Yvonne van Duijnhoven, Erwin Duizer, and Marion Koopmans, RIVM, Bilthoven, the Netherlands, on behalf of the Food-borne viruses in Europe network (fbve@rivm.nl)

An increasing number of acute gastroenteritis outbreaks have been reported in the Netherlands since October 2004 to the Rijksinstituut voor Volksgezondheid en Milieu (RIVM, the Dutch National Institute of Public Health and the Environment) (Table). The early onset of the ‘winter vomiting disease’ season and the high number of reports are unusual. Outbreaks have been reported from different settings, most of which are institutional. So far, all of the outbreaks for which the diagnostic evaluation has been completed are caused by norovirus. This situation may be indicative of a wider trend as several countries have reported higher incidences recently through the global electronic reporting system ProMED-mail (http://www.promedmail.org).

Table. Number of norovirus outbreaks reported in the Netherlands in the winter seasons from 2000/2001 to 2004/2005

 
September
October
November
December
January
February
March
2000/2001
3
1
4
3
13
11
8
2001/2002
2
6
8
14
18
12
8
2002/2003
7
11
33
52
26
12
2
2003/2004
1
1
1
2
9
4
3
2004/2005
9
18
31
13**
-
-
-

**: Number of norovirus outbreaks reported in the first 2 weeks of December. An additional five outbreaks are under investigation.

We would like to share this observation, because we suspect a repeat of the situation in 2002. In that year, the Food-borne viruses in Europe network (FBVE, http://www.eufoodborneviruses.co.uk/) saw a sharp increase in the number of norovirus outbreaks across Europe, and an increase was also reported in the United States. This had a major impact on hospitals and other settings such as nursing homes and cruise ships. The large increase in 2002 was associated with the introduction of a new variant norovirus within the GGII.4 genotype. This virus was first detected early in 2002, and had replaced the resident virus population by mid-summer in all the countries in Europe that were participating in the Food-borne Viruses in Europe network [1,2]. In the United Kingdom, the cost of the 2002 epidemic was calculated to be approximately US$184 million [3].

In the Netherlands outbreaks analysed so far in 2004, another new lineage (GGII.4-2004) within the GGII.4 genotype has been found. This variant is distinct from the 2002 variant strain (GGII.4-2002). Since the beginning of August 2004, 71 norovirus outbreaks have been reported in the Netherlands. Of these, viruses from 44 outbreaks were characterised by sequence analysis, and all 44 belong to the new GGII.4 lineage.

This variant has already been highly active in Australia during the 2004 southern hemisphere winter season (personal communication, Michael Lyon, Public Health Virology Laboratory, Queensland Health Scientific Services, Brisbane, Queensland, Australia, 2004). It caused many outbreaks in different settings and has now almost completely disappeared in the southern hemisphere with the onset of warmer weather.

Since the outbreak season for norovirus in the Netherlands normally starts in December and peaks in January, we believe that a warning that a worldwide increase of outbreaks comparable to 2002 might be on its way is appropriate.

Although data analysis needs to be finalised, we have indications from the FBVE surveillance that GGII.4 is more commonly associated with outbreaks in institutional settings than other norovirus variants; this suggests that the norovirus GGII.4 genotype has properties facilitating transmission, and thereby has the propensity to cause epidemics.

We are continuing to monitor the situation in Europe and are studying the difference in virulence between strains, biological background of the mechanism for its rapid dissemination, and insight into the micro-evolution of noroviruses. Details on the genetic background of these variant noroviruses can be obtained by sending an email to fbve@rivm.nl. We have used the polymerase gene primers for monitoring purposes, and sequence properties are given below. The FBVE network will monitor noroviruses as part of the activities in the EU-funded DIVINE project. We would also be interested to hear from parties outside the participating countries.

Prevention
There are some protocols for healthcare settings [4], hotels and cruise ships available in the literature. Guidelines in these protocols are partly evidence-based and partly common sense, and the effectiveness of some of these measures is subject to debate. Therefore, controlled intervention studies are needed in order to apply evidence-based practice during outbreaks in institutional settings, especially nursing homes and homes for the elderly. Until results of such studies are available, their effectiveness in controlling outbreaks is not clear for all settings.

With these caveats, the following common prevention measures are recommended:

  • isolation of affected persons;
  • use of gloves and facial masks while cleaning contaminated areas;
  • cleaning of contaminated areas with disinfectants containing 1000 – 5000 ppm of hypochlorite, carpets with steam. Chadwick et al suggest the use of hypochlorite at 1000 ppm for disinfection [4], although recent reports suggest that this concentration may be too low for efficient inactivation of NoV and levels of 3000 to 5000 ppm free chlorine may be more appropriate [5,6];
  • washing of contaminated bed linen at least at 70º C using detergents, preferably containing bleach;
  • particular attention to door handles, taps, toilet or bath rails;
  • frequent handwashing;
  • no return to work until 48-72 hours after compete resolution of symptoms for affected staff, and education on virus shedding which may continue for weeks.


Figure. Sequence alignment of norovirus GGII.4 lineages. GGII.4 cons is the consensus sequence of strains prevalent before 2002, GGII.4 2002 is the consensus sequence of the strain that was dominant in the 2002/2003 winter season, GGII.4 2004 is the consensus sequence of the strain that has become dominant during 2004. The sequence is from the RNA dependent RNA polymerase gene, the region upstream of the conserved YGDD motif. Eleven informative positions in the alignment have been highlighted with an asterisk above the sequence. In these positions one sequence is different from the other two.

References:
  1. Lopman B, Vennema H, Kohli E, Pothier P, Sanchez A, Negredo A, et al, for the European Food-borne viruses Network. Increase in viral gastroenteritis outbreaks in Europe and epidemic spread of new norovirus variant. Lancet 2004;363(9410):682-8
  2. Koopmans M, Vennema H, Heersma H, van Strien E, van Duynhoven Y, Brown D, et al, European Consortium on Foodborne Viruses. Early identification of common-source foodborne virus outbreaks in Europe. Emerg Infect Dis 2003;9:1136-42. (http://www.cdc.gov/ncidod/EID/vol9no9/02-0766.htm)
  3. Lopman BA, Reacher MH, Vipond IB, Hill D, Perry C, Halladay T, et al. Epidemiology and cost of nosocomial gastroenteritis, Avon, England, 2002-2003. Emerg Infect Dis 2004;10:1827-34. (http://www.cdc.gov/ncidod/EID/vol10no10/03-0941.htm)
  4. Chadwick PR, Beards G, Brown D, Caul EO, Cheesbrough J, Clarke I, et al. Management of hospital outbreaks of gastro-enteritis due to small round structured viruses. J Hosp Infect 2000:45:1-10.
  5. Barker J, Vipond IB, Bloomfield SF. Effects of cleaning and disinfection in reducing the spread of Norovirus contamination via environmental surfaces. J Hosp Infect 2004;58(1):42-9.
  6. Duizer E, Bijkerk P, Rockx B, De Groot A, Twisk F, Koopmans M. Inactivation of caliciviruses. Appl Environ Microbiol 2004 ; 70(8):4538-43.

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