Norovirus

Norovirus is a group of highly contagious viruses that cause short-term gastroenteritis symptoms including nausea, vomiting, diarrhoea, and potentially chills and fever. Norovirus infection can occur by contact with a person carrying the virus, touching or using contaminated surfaces (e.g., door knobs, light switches, utensils), food or drinking water. Infections are more common in winter as colder temperatures favour virus survival. Most individuals who become ill recover in 1 – 2 days without needing medical treatment; however, dehydration can be a serious side-effect, especially for young children, the elderly, pregnant women, and those with compromised immune systems.

Norovirus outbreaks are typically associated with long-term care facilities, daycares, cruise ships, or other public places where people are in proximity to one another. The resources listed here are intended to assist public health practitioners, food handlers, and health care providers to 1) quickly access resources on norovirus; 2) provide guidance on dealing with outbreaks in closed communities; and 3) highlight the wide range of norovirus resources, e.g., fact sheets, scientific literature, videos, and podcasts, available via the U.S. Centres for Disease Control and Prevention (US CDC) website.

• There are many types (genotypes) of norovirus; thus, norovirus illness can occur more than once (US CDC, 2016a).
• An infected adult can shed billions of virus particles in their vomit and stool (US CDC, 2016b), even up to three days after becoming symptom-free (Public Health Agency of Canada, 2014).
• Exposure to fewer than 20 virus particles can cause illness (US CDC, 2016a).
• There is no vaccine to prevent norovirus infection (US CDC, 2016b).
• Good hand hygiene/proper hand washing is key to preventing norovirus spread.
• In Canada, total annual hospitalizations caused by norovirus (2006-2011) are estimated to be between 4,000 and 11,000, at a cost of $23 million to the healthcare system (Morton et al., 2015).

Selected External Resources

• Chlorine dilution calculator (Public Health Ontario, accessed April 2017)
  This online calculator automatically shows the correct ratio of chlorine:water to mix to create the correct dilution of disinfectant to render norovirus inactive.
   
• Preventing norovirus infection (US CDC, 2016)
  Details about correct hand hygiene, food preparation and cooking, and cleaning and disinfecting contaminated surfaces are found on this web page.
   
• Norovirus: Facts for food workers (US CDC, 2016)
  This fact sheet provides information specific to food handlers, including advice on how long to stay home when you have been ill with norovirus.
   
• For health care providers (US CDC, 2016)
  This web page provides a clinical overview, including symptoms, immunity, and transmission; and information on laboratory diagnosis and treatment. Further information on diagnostic methods (US CDC, 2017) and specimen collection (US CDC, 2016) are also available.
   
• For public health professionals (US CDC, 2016)
  This web page provides information on the burden of norovirus illness and outbreaks in the United States; how to respond to an outbreak, including multiple printable factsheets such as key infection control recommendations; and reporting and surveillance of norovirus in the United States. Trends in norovirus worldwide are also available.
   
• Control of gastroenteritis outbreaks in long-term care homes (Ontario Ministry of Health and Long-Term Care, 2013)
  These guidelines include information on identifying an outbreak, identifying the sources, principles of control, housekeeping, visitors and volunteers, declaring the outbreak over, and include example signage, a hand hygiene fact sheet, and how to correctly use personal protective equipment. Although information is geared towards long-term care homes, it is applicable to other settings.
   
• Norovirus/Norwalk-like Virus (British Columbia Centre for Disease Control, 2012)
  This web page provides information for health professionals on case definition, symptoms, causes, complications, tests and diagnoses, treatment and drugs, and prevention of norovirus.
   
• Norovirus infections in health care settings (British Columbia Centre for Disease Control, 2011)
  This short overview of norovirus in health care settings (e.g., residential care facilities, day care centres, hospitals) provides information on norovirus spread and disinfection methods.
   
• Norovirus and the hospitality industry (Vancouver Coastal Health, 2009)
  These guidelines provide information on cleaning and sanitizing during a norovirus outbreak in a hotel facility or cruise ship. Information is given on exclusion times for ill staff members, and how to monitor and report illnesses.

Peer-Reviewed Articles

• Correlates of protection against norovirus infection and disease – where are we now, where do we go? (Ramani et al., 2016)
  This peer-reviewed article discusses efficacy of a norovirus vaccine in relation to host genetics and immune effectors, including examination of the duration of vaccine immunity, and epidemiological challenges to immunity.
   
• Meta-analysis of the reduction of norovirus and male-specific coliphage concentrations in wastewater treatment plants (Pouillot et al., 2015)
  This meta-analysis examines how male-specific coliphage (MSC) concentrations, an indicator of fecal contamination in water and thus of norovirus, are reduced after different water treatments, providing insight into best practices for waste water treatment plant operators under certain conditions to help reduce norovirus in effluent.
   
• Infection control for norovirus (Barclay et al., 2014)
  This peer-reviewed article reviews the epidemiology of norovirus, prevention and control guidelines, and focuses on the principles of disinfection and decontamination.

This list is not intended to be exhaustive. Omission of a resource does not preclude it from having value.