Data from: Quantifying the relative effects of environmental and direct transmission of norovirus

Background: 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 has
hitherto not been quantified. Objective: 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. Results: The reproduction number for
environmental and direct transmission combined is Rtot = 7.2 [6.1,9.5],
and of environmental transmission alone is Renviron = 1.6 [0.9,2.6].
Direct transmission is overwhelmingly due to passenger-to-passenger
contacts, but crew can act as a reservoir of infection from
cruise-to-cruise. Implications: 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.