title: Norovirus shedding among food and healthcare workers exposed to the virus in outbreak settings.
abstract: Noroviruses (NoV) are highly contagious and the leading cause of nonbacterial outbreaks of gastroenteritis worldwide. Individuals who are infected asymptomatically may act as reservoirs and facilitate the transmission of NoV, but the likelihood of workers of becoming infected in outbreak settings has not been systematically studied.
  
  
  
  We evaluated the occurrence of norovirus infections among workers exposed to the virus in different outbreak settings.
  
  
  
  We screened feces from food handlers and healthcare workers related with gastroenteritis outbreaks, and shedding concentrations over time were calculated from serial samples of infected individuals. Sequence analyses of the capsid P2 domain and region C were used to evaluate linkage between asymptomatic employees and outbreak cases.
  
  
  
  Of all employees, 59.1% were positive for NoV, and more than 70% of them were asymptomatic. Asymptomatic infections were significantly more frequent in foodborne compared to person-to-person transmitted outbreaks; and in restaurants and hotels, compared to nursing homes and healthcare institutions. Mean viral loads were similar between symptomatic and asymptomatic individuals, starting at 7.51±1.80 and 6.49±1.93 log10 genome copies/g, respectively, and decreasing to 5.28±0.76 and 4.52±1.45 log10 genome copies/g after 19days.
  
  
  
  The likelihood of becoming infected when a NoV outbreak occurs at the work place is high and similar between food handlers and healthcare workers, but asymptomatic infections are more frequently identified among food handlers. Since shed amounts of viruses in the absence of symptoms are also high, reinforcement of hygiene practices among workers is especially relevant to reduce the risk of virus secondary transmissions.
authors.affiliation: Enteric Virus Group, Department of Microbiology, University of Barcelona, Avda Diagonal 643, 08028 Barcelona, Spain; Nutrition and Food Safety Research Institute (INSA-UB), University of Barcelona, Avda Prat de la Riba 171, 08921 Santa Coloma de Gramanet, Spain.
authors.forename: Aurora
authors.initials: A
authors.lastname: Sabrià
authors.affiliation: Enteric Virus Group, Department of Microbiology, University of Barcelona, Avda Diagonal 643, 08028 Barcelona, Spain; Nutrition and Food Safety Research Institute (INSA-UB), University of Barcelona, Avda Prat de la Riba 171, 08921 Santa Coloma de Gramanet, Spain.
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Pintó
authors.affiliation: Enteric Virus Group, Department of Microbiology, University of Barcelona, Avda Diagonal 643, 08028 Barcelona, Spain; Nutrition and Food Safety Research Institute (INSA-UB), University of Barcelona, Avda Prat de la Riba 171, 08921 Santa Coloma de Gramanet, Spain.
authors.forename: Albert
authors.initials: A
authors.lastname: Bosch
authors.affiliation: Laboratory of Microbiology, Hospital Universitari Vall d'Hebron, Pssg Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Bartolomé
authors.affiliation: Laboratory of Microbiology, Hospital Universitari Vall d'Hebron, Pssg Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: Thais
authors.initials: T
authors.lastname: Cornejo
authors.affiliation: Department of Health, Generalitat of Catalonia, Roc Boronat 81-95, 08005 Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Instituto de Salud Carlos III, Monforte de Lemos 5, 28029 Madrid, Spain; Department of Public Health, University of Barcelona, Casanova 143, 08036 Barcelona, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Torner
authors.affiliation: Department of Health, Generalitat of Catalonia, Roc Boronat 81-95, 08005 Barcelona, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Martínez
authors.affiliation: Laboratory of the Public Health Agency, Pl. Lesseps 1, 08024 Barcelona, Spain.
authors.forename: Mercedes de
authors.initials: M
authors.lastname: Simón
authors.affiliation: CIBER Epidemiología y Salud Pública (CIBERESP), Instituto de Salud Carlos III, Monforte de Lemos 5, 28029 Madrid, Spain; Department of Public Health, University of Barcelona, Casanova 143, 08036 Barcelona, Spain.
authors.forename: Angela
authors.initials: A
authors.lastname: Domínguez
authors.affiliation: Enteric Virus Group, Department of Microbiology, University of Barcelona, Avda Diagonal 643, 08028 Barcelona, Spain; Nutrition and Food Safety Research Institute (INSA-UB), University of Barcelona, Avda Prat de la Riba 171, 08921 Santa Coloma de Gramanet, Spain. Electronic address: susanaguix@ub.edu.
authors.forename: Susana
authors.initials: S
authors.lastname: Guix
mesh_terms: D000328:Adult; D000368:Aged; D017250:Caliciviridae Infections / Q000453:epidemiology / Q000821:virology*; D004196:Disease Outbreaks; D005243:Feces / Q000821:virology; D005260:Female; D005511:Food Handling; D005759:Gastroenteritis / Q000453:epidemiology / Q000821:virology*; D005838:Genotype; D060005:Genotyping Techniques; D006282:Health Personnel; D006801:Humans; D008297:Male; D008875:Middle Aged; D017422:Sequence Analysis, DNA; D013997:Time Factors; D019562:Viral Load; D014764:Viral Proteins / Q000235:genetics; D017201:Virus Shedding; D055815:Young Adult
chemical_list: D014764:Viral Proteins
keywords: Asymptomatic infections; Food handler; Healthcare worker; Norovirus; P2 domain; Shedding