Norovirus transmission on cruise ship

Abstract

An outbreak of norovirus gastroenteritis affected passengers on two consecutive cruises of ship X and continued on 4 subsequent cruises despite a 1-week sanitization. We documented transmission by food and person-to-person contact; persistence of virus despite sanitization onboard, including introductions of new strains; and seeding of an outbreak on land.

Figure 1

Number (%) of cases of acute gastroenteritis among 513 passengers and 74 crew by date of symptom onset reported to the infirmary on 6 consecutive cruises of ship X, November 2002–January 2003. Arrows indicate start and end of each cruise. pax; passengers.

Figure 2

Phylogram of 9 norovirus sequence types detected in outbreaks on ship X, 4 reference sequences from GenBank, and the Farmington Hills virus. The tree is based on a 277-nucleotide region (region C) of the capsid gene and was created using uncorrected distances calculated by the DISTANCES program (Genetics Computer Group, Madison, WI) and was constructed by neighbor-joining using the GROWTREE program version 10.3 (Genetics Computer Group). Numbers in parenthesis indicate number of samples with the identical sequence detected in a given outbreak. Box highlights sequence types belonging to the Farmington Hills virus that are indistinguishable in region C. GenBank accession no. for reference strains include Bristol virus, X76716; Toronto virus, U02030; Hawaii virus, U07611; and Norwalk virus, M87661. Scale bar represents 10% divergence.