title: Norwalk virus-associated gastroenteritis traced to ice consumption aboard a cruise ship in Hawaii: comparison and application of molecular method-based assays.
abstract: Investigation of an outbreak of acute nonbacterial gastroenteritis on a cruise ship provided an opportunity to assess new molecular method-based diagnostic methods for Norwalk virus (NV) and the antibody response to NV infection. The outbreak began within 36 h of embarkation and affected 30% of 672 passengers and crew. No single meal, seating, or food item was implicated in the transmission of NV, but a passenger's risk of illness was associated with the amount of ice (but not water) consumed (chi-square for trend, P = 0.009). Of 19 fecal specimens examined, 7 were found to contain 27-nm NV-like particles by electron microscopy and 16 were positive by PCR with very sensitive NV-specific primers, but only 5 were positive by a new highly specific antigen enzyme immunoassay for NV. Ten of 12 serum specimen pairs demonstrated a fourfold or greater rise in antibody titer to recombinant baculovirus-expressed NV antigen. The amplified PCR band shared only 81% nucleotide sequence homology with the reference NV strain, which may explain the lack of utility of the fecal specimen enzyme immunoassay. This report, the first to document the use of these molecular method-based assays for investigation of an outbreak, demonstrates the importance of highly sensitive viral diagnostics such as PCR and serodiagnosis for the epidemiologic investigation of NV gastroenteritis.
authors.affiliation: Division of Viral and Rickettsial Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333.
authors.forename: A S
authors.initials: AS
authors.lastname: Khan
authors.forename: C L
authors.initials: CL
authors.lastname: Moe
authors.forename: R I
authors.initials: RI
authors.lastname: Glass
authors.forename: S S
authors.initials: SS
authors.lastname: Monroe
authors.forename: M K
authors.initials: MK
authors.lastname: Estes
authors.forename: L E
authors.initials: LE
authors.lastname: Chapman
authors.forename: X
authors.initials: X
authors.lastname: Jiang
authors.forename: C
authors.initials: C
authors.lastname: Humphrey
authors.forename: E
authors.initials: E
authors.lastname: Pon
authors.forename: J K
authors.initials: JK
authors.lastname: Iskander
mesh_terms: D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000302:isolation & purification; D017250:Caliciviridae Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D004196:Disease Outbreaks; D005243:Feces / Q000382:microbiology; D005759:Gastroenteritis / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D006254:Hawaii / Q000453:epidemiology; D006801:Humans; D007053:Ice / Q000009:adverse effects; D007124:Immunoenzyme Techniques / Q000706:statistics & numerical data; D009663:Norwalk virus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity; D012767:Ships; D014195:Travel; D014773:Virology / Q000379:methods; D014871:Water Microbiology
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D007053:Ice