CDC finalizing norovirus outbreak guidelines

Rarely fatal, but very disruptive and costly

The Centers for Disease Control and Prevention is finalizing new guidelines on prevention of norovirus infections and was expected to release them soon as this issue went to press.

Recently approved by the CDC Healthcare Infection Control Practices Advisory Committee (HICPAC) at a meeting in Washington, DC, the "Guideline for the Prevention and Control of Norovirus Gastroenteritis Outbreaks in Healthcare Settings" includes the latest information on preventing the bane of cruise ships and hospitals alike.

A series of outbreaks in the last few years seems to have lulled, but no doubt norovirus will be a problem in some hospital or nursing home all too soon.

"These things tend to come in waves and every season is not the same," says Michael Bell, MD, HICPAC, executive secretary and deputy director of the CDC Division of Healthcare Quality Promotion. "I have no doubt that with the amount of long-term care facilities, day care facilities and other communal living situations — not to mention the growth of the cruise ship industry — that we will continue to see plenty of norovirus outbreaks."

Though rarely including fatal infections, norovirus outbreaks are extremely disruptive and expensive to control. Long-term care settings are particularly vulnerable to outbreaks due to the low infectious dose of norovirus (fewer than 10 viral particles), its persistence in the environment, and the close quarters and interaction typical among residents. Many of the outbreaks have been associated with breaches in infection control measures, which include frequent hand disinfection, contact precautions with known patients and use of bleach or another appropriate disinfectant for evironmental cleaning. Outbreaks have also been preceded by symptomatic illness in food handlers, reminding that norovirus can be a foodborne pathogen as well as transmitted through direct fecal-oral contact and through the environment. Transmission also goes the other way too, as outbreaks may include health care workers — some infected severely enough to be hospitalized.

"In this document there is a lot of emphasis on containment and environmental hygiene and cleaning," Bell says. "This is one of those things that is persistent in the environment, so there are several recommendations beyond routine cleaning to bring an outbreak to a close. The other issue is to make sure that the outbreak is promptly reported to state health authorities because it may not be purely hospital based. It's often a reflection of something happening in the community."

While the final version is under internal review at the CDC, the draft version of the document discussed at the HICPAC meeting included background information and key recommendations summarized as follows:

Background: Norovirus is the most common etiological agent of acute gastroenteritis and is often responsible for outbreaks in a wide spectrum of community and healthcare settings. Illness is typically self-limiting, with acute symptoms of fever, nausea, vomiting, cramping, malaise, and diarrhea persisting for 2 to 5 days. However, it is estimated that norovirus may be the causative agent in over 23 million gastroenteritis cases every year in the United States, representing approximately 60% of all acute gastroenteritis cases. Norovirus leads to over 91,000 emergency room visits and 23,000 hospitalizations for severe diarrhea among children under the age of five each year in the United States. Infections are seen in all age groups, although severe outcomes and longer durations of illness are most likely to be reported among the elderly.

Among hospitalized patients who may be immunocompromised or have significant medical comorbidities, norovirus infection can directly result in a prolonged hospital stay, additional medical complications, and, rarely, death. Immunity after infection is strain-specific and appears to be limited in duration to a period of several weeks, despite the fact that seroprevalence of antibody to this virus reaches 80%-90% as populations transition from childhood to adulthood. There is currently no vaccine available for norovirus and, generally, no medical treatment is offered for infection apart from oral or intravenous repletion of volume.

In healthcare settings, norovirus may be introduced into a facility through ill patients, visitors, or staff. Typically, transmission occurs through exposure to direct or indirect fecal contamination found on fomites, by eating foods prepared by ill food-handlers, by contact with body fluids or skin surfaces, or by exposure to aerosols of norovirus from vomiting persons. Healthcare facilities managing outbreaks of norovirus gastroenteritis may experience significant costs relating to isolation precautions and PPE, ward closures, supplemental environmental cleaning, staff cohorting or replacement, and sick time.

Selected recommendations

• Begin active case-finding when a cluster of acute gastroenteritis cases is detected in the healthcare facility. Use a defined case definition to populate line lists to track both exposed and symptomatic patients and staff. Collect relevant epidemiological, clinical, and demographic data as well as information on patient location and outcomes.

• Notify appropriate local and state health departments, as required by state and local public health regulations, if an outbreak of norovirus gastroenteritis is suspected.

• During outbreaks, patients with norovirus gastroenteritis should be cohorted or placed on contact precautions for a minimum of 48 hours after the resolution of symptoms to prevent further exposure of susceptible patients. Use a surgical or procedure mask, and eye protection if there is a risk of splashes to the face during the care of patients, particularly among those who are vomiting. Clinical and environmental services staff, as well as visitors, should wear gloves and gowns when entering areas under isolation or cohorting.

• Areas affected by outbreaks of norovirus gastroenteritis should actively promote adherence with hand hygiene among healthcare personnel, patients, and visitors. During outbreaks, use of soap and water is the preferred method of hand hygiene. Consider FDA-approved alcohol-based hand sanitizers as a supplemental method of hand hygiene during outbreaks of norovirus gastroenteritis when hands are not visibly soiled and have not been in contact with diarrheal patients, contaminated surfaces, or blood or other body fluids.

• Increase the frequency of cleaning and disinfection of patient care areas and frequently touched surfaces during outbreaks of norovirus gastroenteritis. Unit level cleaning may be increased up to twice daily, with frequently touched surfaces cleaned and disinfected up to three times daily using EPA-approved products for healthcare settings.

• Facilities should develop and adhere to sick leave policies for healthcare personnel symptomatic with norovirus infection. Ill staff members should be excluded from work for a minimum of 48 hours after the resolution of symptoms. Once staff return to work, adherence to hand hygiene must be maintained.

• During suspected or confirmed outbreaks, preferentially place patients with norovirus gastroenteritis on contact precautions and into private rooms equipped with at least one dedicated handwashing sink and toilet or commode. If these provisions are not available, patients may be cohorted into groups of those who are symptomatic, exposed but asymptomatic, and unexposed with access to separate toilets or commodes for each group. Alternatively, all patients within a hospital unit or section may be placed under contact precautions.

• Minimize patient movements within a ward or unit. Symptomatic and recovering patients should not leave the patient-care area unless it is for essential care or treatment, to reduce the likelihood of environmental contamination and transmission of norovirus in unaffected clinical areas.