Emergence of new norovirus variants on spring cruise ships and prediction of winter epidemics.
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.
Verhoef
Linda
L
Center for Infectious Disease Control, Bilthoven, the Netherlands. linda.verhoef@rivm.nl
Depoortere
Evelyn
E
Boxman
Ingeborg
I
Duizer
Erwin
E
van Duynhoven
Yvonne
Y
Harris
John
J
Johnsen
Christina
C
Kroneman
Annelies
A
Le Guyader
Soizick
S
Lim
Wilina
W
Maunula
Leena
L
Meldal
Hege
H
Ratcliff
Rod
R
Reuter
Gábor
G
Schreier
Eckart
E
Siebenga
Joukje
J
Vainio
Kirsti
K
Varela
Carmen
C
Vennema
Harry
H
Koopmans
Marion
M
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