title: Emergence of new norovirus variants on spring cruise ships and prediction of winter epidemics.
abstract: In June 2006, reported outbreaks of norovirus on cruise ships suddenly increased; 43 outbreaks occurred on 13 vessels. All outbreaks investigated manifested person-to-person transmission. Detection of a point source was impossible because of limited investigation of initial outbreaks and data sharing. The most probable explanation for these outbreaks is increased norovirus activity in the community, which coincided with the emergence of 2 new GGII.4 variant strains in Europe and the Pacific. As in 2002, a new GGII.4 variant detected in the spring and summer corresponded with high norovirus activity in the subsequent winter. Because outbreaks on cruise ships are likely to occur when new variants circulate, an active reporting system could function as an early warning system. Internationally accepted guidelines are needed for reporting, investigating, and controlling norovirus illness on cruise ships in Europe.
authors.affiliation: Center for Infectious Disease Control, Bilthoven, the Netherlands. linda.verhoef@rivm.nl
authors.forename: Linda
authors.initials: L
authors.lastname: Verhoef
authors.forename: Evelyn
authors.initials: E
authors.lastname: Depoortere
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Boxman
authors.forename: Erwin
authors.initials: E
authors.lastname: Duizer
authors.forename: Yvonne
authors.initials: Y
authors.lastname: van Duynhoven
authors.forename: John
authors.initials: J
authors.lastname: Harris
authors.forename: Christina
authors.initials: C
authors.lastname: Johnsen
authors.forename: Annelies
authors.initials: A
authors.lastname: Kroneman
authors.forename: Soizick
authors.initials: S
authors.lastname: Le Guyader
authors.forename: Wilina
authors.initials: W
authors.lastname: Lim
authors.forename: Leena
authors.initials: L
authors.lastname: Maunula
authors.forename: Hege
authors.initials: H
authors.lastname: Meldal
authors.forename: Rod
authors.initials: R
authors.lastname: Ratcliff
authors.forename: Gábor
authors.initials: G
authors.lastname: Reuter
authors.forename: Eckart
authors.initials: E
authors.lastname: Schreier
authors.forename: Joukje
authors.initials: J
authors.lastname: Siebenga
authors.forename: Kirsti
authors.initials: K
authors.lastname: Vainio
authors.forename: Carmen
authors.initials: C
authors.lastname: Varela
authors.forename: Harry
authors.initials: H
authors.lastname: Vennema
authors.forename: Marion
authors.initials: M
authors.lastname: Koopmans
mesh_terms: D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000821:virology; D021821:Communicable Diseases, Emerging / Q000453:epidemiology* / Q000821:virology; D004196:Disease Outbreaks / Q000706:statistics & numerical data; D005060:Europe / Q000453:epidemiology; D005759:Gastroenteritis / Q000453:epidemiology* / Q000821:virology; D014644:Genetic Variation; D006801:Humans; D029322:Norovirus / Q000145:classification / Q000302:isolation & purification*; D011159:Population Surveillance / Q000379:methods; D012621:Seasons; D012767:Ships; D014195:Travel