Quantifying the relative effects of environmental and direct transmission of norovirus

S. Towers, J. Chen, C. Cruz, J. Melendez, J. Rodriguez, A. Salinas, F. Yu, Yun Kang

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Norovirus is a common cause of outbreaks of acute gastroenteritis in health-and child-care settings, with serial outbreaks also frequently observed aboard cruise ships. The relative contributions of environmental and direct person-to-person transmission of norovirus have hitherto not been quantified. We employ a novel mathematical model of norovirus transmission, and fit the model to daily incidence data from a major norovirus outbreak on a cruise ship, and examine the relative efficacy of potential control strategies aimed at reducing environmental and/or direct transmission. The reproduction number for environmental and direct transmission combined is (Formula Presented) =7.2 [6.1, 9.5], and of environmental transmission alone is (Formula Presented) =1.6 [0.9, 2.6]. Direct transmission is overwhelmingly due to passenger-topassenger contacts, but crew can act as a reservoir of infection from cruise to cruise. This is the first quantification of the relative roles of environmental and direct transmission of norovirus. While environmental transmission has the potential to maintain a sustained series of outbreaks aboard a cruise ship in the absence of strict sanitation practices, direct transmission dominates. We find that intensive promotion of good hand washing practices may prevent outbreaks. Isolation of ill passengers and cleaning are beneficial, but appear to be less efficacious at outbreak control.

Original languageEnglish (US)
Article number170602
JournalRoyal Society Open Science
Issue number3
StatePublished - Mar 7 2018


  • Basic reproduction number
  • Epidemiology
  • Mathematical model
  • Norovirus

ASJC Scopus subject areas

  • General


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