Increase in Norovirus Activity in New Hampshire

February 05, 2016

Key Points and Recommendations:

1. Increased awareness and vigilance for outbreaks of gastroenteritis in healthcare facilities, schools, and childcare settings, which may be caused by norovirus.

2. Strict adherence to infection control practices during a suspected outbreak.

3. Awareness of resources for institutional settings experiencing a gastrointestinal outbreak.

4. Timely reporting of all suspected outbreaks to the New Hampshire (NH) Department of Health and Human Services (DHHS) Bureau of Infectious Disease Control at 603-271-4496 (after hours, 603-271-5300).


Since December 1, 2015, the NH Division of Public Health Services (DPHS) has received 16 reports of acute gastroenteritis outbreaks in institutional settings, with 7 outbreaks being reported in the last week alone. Most of these outbreaks are confirmed to have been caused by norovirus, a common viral infection in the United States.

Noroviruses are a group of related, single-stranded RNA, non-enveloped viruses that cause acute gastroenteritis in humans. Three norovirus genogroups can infect humans (GI, GII, GIV). Noroviruses identified in New Hampshire over the last several years are predominantly genogroup II (GII).

Noroviruses are highly communicable and can be transmitted in a number of ways, including person-to-person contact, consumption of contaminated food and water, airborne droplets of vomit, and contact with contaminated surfaces. Symptoms commonly include vomiting and diarrhea, which may be accompanied by abdominal cramps, nausea, fever, or headache. Symptoms usually resolve within 48 hours (range, 12-60 hours). Available treatment is supportive therapy for dehydration.

Infection Control Recommendations During an Outbreak:

Recommendations for All Institutional Settings (Healthcare, Schools, Childcare, etc.)

1. All staff, patients, residents, or students should practice frequent hand washing. Hand washing with soap and running water for at least 20 seconds is the most effective way to reduce norovirus contamination on the hands. Hand washing is particularly important after contact with symptomatic persons, when leaving affected areas, and before handling food or drinks.

2. Whenever contact with a symptomatic patient or contaminated environment is anticipated, use standard precautions (i.e. gloves and aprons). Whenever there is an anticipated risk of splashes to the face during the care of symptomatic patients or during cleaning and disinfection, use a surgical or procedure mask and eye protection or a full face shield, especially when the patient is vomiting.

3. Increase the frequency of cleaning and disinfection of frequently-touched surfaces such as water taps, door handles, and toilet or bath rails.

4. Promptly clean areas contaminated with vomit and feces and then disinfect using freshly prepared sodium hypochlorite with a concentration of 1,000-5,000 ppm (5-25 tablespoons household bleach [5.25%] per gallon of water). Whenever possible, this chlorine bleach solution should be used; however, a commercial product that is EPA-approved as effective against norovirus may be used alternatively. A list of EPA-approved products is available at

5. Clean soiled carpets and soft furnishings with hot water and detergent or steam clean; avoid vacuum cleaning.

6. Review kitchen practices and ensure that all food service workers wear gloves when handling ready-to-eat foods. Assess the health status of food service workers and exclude symptomatic individuals from work until 48 hours after resolution of symptoms.

7. In schools and childcare facilities, assess the health status of students and staff, and exclude all symptomatic individuals from school or work until full recovery.

8. In healthcare facilities, assess the health status of all healthcare workers and exclude symptomatic individuals from direct patient care until 48 hours after the resolution of symptoms.

Additional Recommendations for Healthcare Facilities

9. Restrict or defer admissions to affected units and wards until 96 hours after resolution of the last case.

10. Stop all group activities until 96 hours after resolution of the last case.

11. Exclude non-essential staff from affected areas and interrupt the movement of inter-departmental staff while any patients are symptomatic.

12. Notify visitors and provide instructions regarding hand washing using signage or other messaging tools.

13. Conduct terminal cleaning at least 72 hours after resolution of the last case and prior to opening to admissions and resuming normal activities.

These recommendations are discussed in greater detail in the Centers for Disease Control and Prevention's Norovirus Outbreak Management and Disease Prevention Guidelines available at:

The Healthcare Infection Control Practices Advisory Committee's guideline for the prevention and control of norovirus outbreaks in healthcare settings is available at: Additionally, a toolkit for healthcare facilities experiencing a norovirus outbreak is available at:

Laboratory Testing for Norovirus:

Several commercial laboratories and the NH Public Health Laboratories (PHL) can test stool for norovirus. Available tests use real-time reverse transcriptase polymerase chain reaction (real-time RT-PCR) methods to detect the virus. Although norovirus can sometimes be found in stool samples taken as late as two weeks after symptom recovery, identification of the virus is best made from stool taken within 72 hours of symptom onset.

During suspected outbreaks of norovirus, NH DHHS recommends norovirus testing through the NH PHL (see reporting information below). For specimens not related to an outbreak, fee-based testing at the NH PHL is also available.

Label a sterile container with patient identifiers, then collect the whole stool specimen and place sealed container in a plastic bag. Refrigerate or place samples on ice and deliver to the NH PHL with a completed PHL requisition form as soon as possible for best testing results.

Reporting of Suspected Outbreaks:

Individual cases of norovirus are not reportable in New Hampshire unless suspected to be part of an outbreak. To report suspected outbreaks, call the Bureau of Infectious Disease Control at 603-271-4496 (toll free at 800-852-3345, ext. 4496). After hours, call 603-271-5300 (toll free at 800-852-3345, ext. 5300), and ask for the public health professional on call. The public health professional will discuss appropriate management of the suspected outbreak including laboratory testing. To discuss specific questions about laboratory testing and specimen submission you may also contact the NH PHL at 603-271-4620.

For any questions regarding the contents of this message, please contact NH DHHS, DPHS, Bureau of Infectious Disease Control at 603-271-4496 (after hours, 800-852-3345, ext. 5300).


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