hours but can be as short as 12 hours. This

illness is characterized by:

• Sudden-onset vomiting,

• Watery, non-bloody diarrhea with abdominal cramps, and

• Nausea.

How People Become Infected

According to the CDC, NoVs are highly contagious, with as few as 10-100 virus particles

being sufficient to cause infection. NoVs are

transmitted primarily through food or water

contaminated with fecal material. NoVs can

also spread via droplets of vomit. Transmission can also occur indirectly when the virus

is transferred to the mouth via the hands

after contact with environmental surfaces

that have been contaminated with either

feces or vomit. NoVs are quite stable in the

environment and can survive freezing.

Treatment Options

There are no antiviral drugs for treatment of

NoV infections, and no vaccines are currently

available. Illness usually lasts 24 to 60 hours.

Dehydration is the most common complication and may require intravenous replacement fluids.

How to Limit NoVTransmission

• Practice good hand hygiene: After using the

restroom, sneezing, coughing, and before

and after food preparation, all employees

should:

■ wash their hands with warm running

water and soap, using friction for 15-20

seconds,

■ dry hands with a single-service paper

towel or air dryer, or

The Centers for Disease Control and Prevention (CDC) estimates that each year in the

U.S. NoVs are responsible for approximately

23 million infections resulting in 50,000 hospitalizations. In addition, NoVs are the leading cause of AGE in the U.S., NoV episodes

have taken place on cruise ships and in

healthcare settings (hospitals and nursing

homes), hotels, retirement centers, and

schools.

Although NoVs are currently more of a concern to the general public than to employees,

the increasing incidence of NoV outbreaks

exposes many different employee groups,

especially healthcare workers (HCWs). For

example, in a Maryland hospital in 2004, 265

HCWs developed AGE during a NoV outbreak. The percentage of HCWs affected was

three times higher than the percentage of patients affected. Similarly, in an Oregon longterm care facility in April 2006 a relatively

large number of employees (25) became ill

with AGE.

Employees at Potential Risk of Exposure

• Hotel employees (especially housecleaning

employees);

• Cruise ship employees;

• Food service employees;

• Healthcare (hospital and nursing care) employees treating patients with known or

suspected NoV infections;

• Retirement center employees;

• School/daycare employees.

Symptoms of NoV Infection

According to the CDC, the usual time from

exposure to onset of symptoms is 24 to 48

FactSheet

Noroviruses

Noroviruses (NoVs) were named after Norwalk, Ohio, where a NoV strain (subsequently called the Norwalk strain) caused the first sudden major diarrhea and vomiting outbreak (referred to as acute gastroenteritis or AGE) in 1968. In addition to

causing disease in humans, some NoV strains have caused disease in cows, pigs

and mice. There have been no documented cases of animal NoVs being transmissible to humans or vice versa.
■ if soap and water are not available, use a

waterless, alcohol-based hand rub with a

minimum ethanol concentration of 60%.

• After handling contaminated materials

avoid:

■ touching the face, especially the mouth;

and

■ eating, drinking, smoking, applying lip

balm or any facial cosmetics.

• Wear disposable gloves, surgical masks, eye

protection or faceshields, and a gown or

protective clothing:

■ when caring for diapered or incontinent

persons,

■ during outbreaks in a facility,

■ when there is the possibility of splashes

that might lead to contamination of clothing, and

■ when cleaning areas heavily contaminated

with vomit or feces.

• During an outbreak, it may be best to place

patients with suspected NoV in private

rooms or to group such patients.

Disinfecting Environmental Surfaces

Any surface (porous or non-porous) that is

likely to have been contaminated by oral or

fecal secretions from a NoV-infected person

should be disinfected.

Most effective disinfectants

The CDC recommends using either chlorine

bleach or U.S. Environmental Protection

Agency (EPA)-approved disinfectants to control NoV outbreaks. All disinfectants should

be used on clean surfaces (i.e., surfaces that

are not visibly soiled) for maximum performance.

Chlorine bleach

Concentrations and mixing instructions

Use for food/mouth contact items, toys;

1 tablespoon of bleach in 1 gallon water

(1:250 dilution).

Use for most non-porous surfaces:

1/3 cup bleach in 1 gallon water (1:50 dilution).

Use for heavily contaminated non-porous

surfaces:

1 and 2/3 cups bleach in 1 gallon water (1:10

dilution).

Contact time

Leave bleach on surface for 10-20 minutes

and then rinse thoroughly with clean water.

Stability of Chlorine Bleach

• Once opened, bottles of household bleach

will lose effectiveness after 30 days.

• Use a new unopened bottle of bleach every

30 days for preparing diluted disinfectant

solutions.

• Prepare a fresh dilution of bleach (only from

bleach bottles that have not been open for

more than 30 days) every day of use and

discard unused portions.

Other disinfectants

Heat disinfection [i.e., pasteurization to 140° F

(60°C)] has been used successfully under laboratory conditions for items that cannot be

subjected to chemical disinfectants such as

chlorine bleach.

EPA’s Registered Antimicrobial Products

Effective Against NoVs

EPA-registered disinfectants should be used

according to manufacturers’ instructions, including the use of proper PPE recommended

by the manufacturer when applying the product. For a list of these disinfectants see:

www.epa.gov/oppad001/list_g_norovirus.

pdf).

Cleaning large spills of vomit or feces

• Visible/organic debris should be removed

carefully to minimize airborne particles. Use

double-layered absorbent material and discard in a sealed plastic bag.

• Liberally disinfect area and objects surrounding the contamination with an appropriate environmental disinfectant (multiple

applications may be required).

• Ensure appropriate dilution and contact time

for the environmental disinfectant.

Non-porous surfaces; Hard surfaces

• Examples include: bath rails, chairs (all

wooden, plastic, and steel parts), counters,

doorknobs, elevator buttons, faucets,

handrails, light switches, phones, tables, toilets, sinks, etc.)

• Disinfect with chlorine bleach; rinse with

water for food preparation areas.

Porous surfaces: Carpets/Upholstered

Furniture

• Examples include carpets and upholstered

chairs and sofas.

• Visible debris should be cleaned with ab-
sorbent material (double layer) and discarded in a plastic bag to minimize airborne

particles.

• Steam clean (heat inactivation) 158° F for 5

minutes or 212° F for 1 minute for complete

inactivation. Disinfecting with bleach may

discolor carpets and/or upholstered furniture.

Other porous surfaces: Clothing/linens/

textiles

• Examples include: aprons, bedding, linens,

mattress covers, uniforms, window coverings.

• If soiled, vomit or feces should be carefully

removed to minimize airborne particles that

may pose a risk for transmission. Do not

shake soiled linens and laundry. Soiled

linens should be placed directly into a bag

at the point of removal.

• Ensure proper separation of clean and

soiled laundry.

• Wash items in a pre-wash cycle, then use a

regular wash cycle using detergent.

• Dry contaminated material separately at a

temperature greater than 170° F.

• It may be best to discard certain soiled materials rather than risk exposure during

cleaning.

• For additional laundry information see:

www.cdc.gov/ncidod/dhqp/gl_environ infection.html.

Ice Machines

• Contaminated ice machines must be disinfected.

For procedures, see: www.cdc.gov/ncidod/

dhqp/pdf/guidelines/Enviro_guide_03.pdf.

What Ill Employees Should Do

• Ill employees should be sent home immediately.

• Employees who have been ill with suspected NoV should not return to work for 48 to

72 hours after symptoms have ended.

• Do not travel while sick; stay home and limit

contact with others as much as possible to

help prevent the spread of the virus.

Additional Procedures that Healthcare

Facilities Should Follow

Occupational Health Policies

• Refer to Occupational Health unit for employee health policies on work restrictions

and return to work policies (See: www.cdc.

gov/ncidod/dhqp/gl_hcpersonnel.html).

Medical Equipment Cleaning Precautions

• Medical equipment used for care of NoV-infected patients should be either:

■ dedicated to that room for the duration of

isolation, or

■ be thoroughly disinfected upon removal

from the room.

• Selection of appropriate cleaning agents

should be consistent with the equipment

manufacturer’s recommendations.

• Some medical equipment may not be able

to be immersed in liquid disinfectants. Follow your facility’s infection control plan

and/or the equipment manufacturer’s instructions for appropriate disinfection procedures for medical equipment.

Cleaning Procedures

• For cleaning procedures (i.e., changing

water/washcloths, sequence of cleaning)

refer to CDC/HICPAC (Healthcare Infection

Control Practices Advisory Committee) Environmental Infection Control in Healthcare

Facilities, 2003. (See: www.cdc.gov/ncidod/

dhqp/gl_environinfection.html.)

Training

Employees with potential for NoV exposure

should receive training on hazards associated

with exposure to NoVs and on hazards the

procedures in place in their facility to isolate

and report cases and reduce exposures.

Additional Information

Centers for Disease Control and Prevention

(CDC) Norovirus (last updated June 6, 2006):

www.cdc.gov/ncidod/dvrd/revb/gastro/

norovirus.htm

Environmental Protection Agency (EPA):

List G: EPA’s Registered Antimicrobial Products Effective Against Norovirus (Norwalk-like

virus) January 16, 2007.

www.epa.gov/oppad001/list_g_norovirus. pdf
This is one in a series of informational fact sheets highlighting OSHA programs, policies or

standards. It does not impose any new compliance requirements. For a comprehensive list of

compliance requirements of OSHA standards or regulations, refer to Title 29 of the Code of Federal

Regulations. This information will be made available to sensory impaired individuals upon request.

The voice phone is (202) 693-1999; teletypewriter (TTY) number: (877) 889-5627.

U.S. Department of Labor

www.osha.gov

(800) 321-OSHA

For more complete information:

DSG 05/2008