Quantitative microbial risk assessment of human norovirus infection in environmental service workers due to healthcare-associated fomites

K N Overbey; G B Hamra; K E Nachman; C Rock; K J Schwab

doi:10.1016/j.jhin.2021.08.006

Quantitative microbial risk assessment of human norovirus infection in environmental service workers due to healthcare-associated fomites

J Hosp Infect. 2021 Nov:117:52-64. doi: 10.1016/j.jhin.2021.08.006. Epub 2021 Aug 14.

Authors

K N Overbey¹, G B Hamra², K E Nachman³, C Rock⁴, K J Schwab⁵

Affiliations

¹ Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
² Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
³ Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA; Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA; Risk Sciences and Public Policy Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
⁴ Division of Infectious Diseases, Johns Hopkins Medicine, Baltimore, MD, USA.
⁵ Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA; Risk Sciences and Public Policy Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. Electronic address: kschwab1@jhu.edu.

Abstract

Background: Healthcare-associated norovirus outbreaks place a large burden on healthcare staff. Environmental service workers (ESWs), however, remain understudied despite high contact with potentially contaminated surfaces. Understanding the magnitude of the risk of norovirus infection in healthcare ESWs can protect workers and improve infection control.

Aim: This study simulated the risk of norovirus infection for unprotected ESWs after a single fomite contact, assuming no disinfection or protective equipment, in norovirus-positive patient rooms. In addition, the risk of secondary surface transmission from norovirus-exposed ESWs was simulated.

Methods: A quantitative microbial risk assessment employing two-dimensional Monte Carlo simulation with parameters extracted from the literature was used to estimate norovirus infection from multiple fomite contact scenarios defined by: norovirus source (patient vomit/diarrhoea), location (bathroom/patient room) and target outcome (ESW/secondary illness).

Findings: Unprotected ESWs have a maximum estimated risk of norovirus infection of 33% (1:3) for a single fomite contact in a room where a norovirus-positive patient had a diarrhoeal event. Patient vomit events lead to fomite contact risk estimates that are four orders of magnitude lower than those for diarrhoeal events. The estimated risk of secondary illness from touching a common surface is as high as 25% (1:4) after single fomite exposure following a diarrhoeal event.

Conclusions: A single fomite contact may lead to sizable risk of norovirus infection in ESWs if personal protective equipment and disinfection are not used appropriately. ESWs can also transfer virus to secondary surfaces, initiating further infections. Interventions are needed to reduce fomite transfer of norovirus, and protect patients and staff from nosocomial infections.

Keywords: Environmental service workers; Fomite; Health care; Norovirus; Risk assessment.

MeSH terms

Caliciviridae Infections* / epidemiology
Delivery of Health Care
Fomites
Humans
Norovirus*
Risk Assessment

Abstract

MeSH terms

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