Norovirus (NoV)

Characteristics
Morphology	Family: Caliciviridae; Genus: Norovirus; Species: Norwalk. There are six genogroups (G). Single stranded RNA virus; non-enveloped, 27-32 nm virion. Norovirus recombination and antigenic drift results in replacement of circulating dominant viruses every 2-3 years, with the new variants able to re-infect hosts immune to previous viruses
Growth Conditions	Human norovirus is difficult to culture in vitro. Surrogate viruses that can be maintained in vitro: coliphage MS2, murine norovirus (MNV) and feline calicivirus (FCV).

Health Hazards
Host Range	Humans (GI, GIII, GIV), bovine (GIII), mice (GV)
Modes of Transmission	Norovirus must enter the digestive track in order to initiate infection. Frequent routes include: fecal-oral, contaminated food or water, person-to-person, contaminated fomites or body fluids, and aerosolized contaminated particles. The infection is usually resolved within 12 to 60 hours, although it can last longer in elderly, young children or immunocompromised individuals
Signs and Symptoms	Norovirus infection causes acute gastroenteritis, characterized by rapid onset of nausea, vomiting, diarrhea, abdominal cramps, abdominal pain, mucus in stool, malaise, headache, and fever.
Infectious Dose	Less than 10 virions in some cases
Incubation Period	Incubation 12-48 h

Medical Precautions/Treatment
Prophylaxis	Hand washing with soap and water, limiting contact with contaminated food, water, surfaces or body fluids.
Vaccines	None publically available
Treatment	There is no specific therapy to treat NoV other than rest, oral rehydration and intravenous electrolyte replacement. Seek medical attention if they become severe.
Surveillance	Monitor for symptoms. Viral RNA can be detected in stool samples using reverse transcription PCR. ELISA is also available for identifying noroviruses
GWU Requirements	Report all incidents to the Office of Risk Management as well as the Office of Research Safety (ORS) IMMEDIATELY FOLLOWING THE OCCURRENCE.

Containment
BSL-2	Risk Group 2 classification is applied to NoV. BSL-2 practices and containment equipment for all activities involving the virus or any infectious or potentially infectious body fluids or tissues. All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC).

Spill Procedures
Small Spills (<1 liter)	If the spill occurred inside a biological safety cabinet, close the sash and allow the cabinet to operate for 15 minutes before continuing with the spill cleanup. While NoV exposure via aerosol transmission is uncommon, but caution should still be taken during a spill outside of a BSC. Leave the room immediately and allow the aerosols to dissipate for 15 minutes. Notify others working in the lab. Don appropriate PPE. Cover area of the spill with paper towels or any absorbent material and apply an EPA registered disinfectant effective against non-enveloped viruses (bleach, glutaraldehyde, and peroxide), working from the perimeter towards the center. Allow 30 minutes of contact time before disposal and cleanup of spill materials.
Large Spills	Alert lab personnel in the laboratory to the spill and keep people out of the area to prevent spread of the contamination. Check if you have been contaminated or if any of your PPE has been breached. If so follow exposure procedures. Remove any contaminated clothing and place it the biohazard waste. Wash your hands and post a sign on the door. Notify your supervisor of the incident and call ORS (4-8258) for assistance. If the situation involves an imminently life-threatening injury or has catastrophic potential, call 911.

Spill Procedures

Small Spills (<1 liter)

If the spill occurred inside a biological safety cabinet, close the sash and allow the cabinet to operate for 15 minutes before continuing with the spill cleanup.

While NoV exposure via aerosol transmission is uncommon, but caution should still be taken during a spill outside of a BSC. Leave the room immediately and allow the aerosols to dissipate for 15 minutes. Notify others working in the lab. Don appropriate PPE. Cover area of the spill with paper towels or any absorbent material and apply an EPA registered disinfectant effective against non-enveloped viruses (bleach, glutaraldehyde, and peroxide), working from the perimeter towards the center. Allow 30 minutes of contact time before disposal and cleanup of spill materials.

Large Spills

Alert lab personnel in the laboratory to the spill and keep people out of the area to prevent spread of the contamination. Check if you have been contaminated or if any of your PPE has been breached. If so follow exposure procedures. Remove any contaminated clothing and place it the biohazard waste. Wash your hands and post a sign on the door. Notify your supervisor of the incident and call ORS (4-8258) for assistance. If the situation involves an imminently life-threatening injury or has catastrophic potential, call 911.

Exposure Procedures
Mucus Membrane	Flush eyes, mouth or nose for 15 minutes at eyewash station.
Other Exposure	Wash area with soap and water for 15 minutes. Alcohol-based hand disinfectants are NOT effective
Reporting	Report ALL injuries to the PI immediately and reported to the Office of Risk Management at [email protected] IMMEDIATELY FOLLOWING THE OCCURRENCE. Exposures that involve a bloodborne-pathogen or recombinant DNA also need to be reported to the Office of Research Safety at [email protected]. If the injury requires immediate medical attention, call GWPD at 202-994-6111 or call 911.
Medical Monitoring	Seek immediate medical evaluation, treatment, and post exposure follow-up at the Employee Health Office at GWU Hospital (900 23rd St., NW, Suite G-1090, Phone: 202-715-4275). Students should go to the Students Health Office at Marvin Center. After hours treatment can be received at the GWU hospital emergency room.

Stability
Disinfection	10% fresh bleach solution, a minimum of 10 min contact time is required. Alcohol alone is NOT an effective disinfectant against AdV.
Inactivation	Noroviruses are inactivated by temperatures of 71.3°C for 1 minute. It can survive at pH 2.7 for at least 3 hours. UV radiation may have intermediate effect
Survival Outside Host	Can survive in seawater, groundwater, fresh water, soil, and inanimate surfaces for an unknown period of time.

Personal Protective Equipment (PPE)
Minimum PPE Requirements	At minimum, personnel are required to don gloves, closed toed shoes, lab coat, and appropriate face and eye protection prior to working with NoV. Additional PPE may be required depending on lab specific SOPs.
Additional Precautions	Additional protection may be worn over laboratory clothing when infectious materials are directly handled, such as solid-front gowns with tight fitting wrists and gloves.

References
CDC (https://www.cdc.gov/norovirus/index.html) EPA (https://www.epa.gov/pesticide-registration/list-g-epas-registered-antim…) In Vitro Replication of Human Norovirus (https://www.mdpi.com/1999-4915/11/6/547/htm) Canadian PHAC (https://www.canada.ca/en/public-health/services/laboratory-biosafety-bi…)