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Norovirus Updates for Williamson County
Since January 1, 2010, WCCHD is investigating two outbreaks of
a norovirus-like illness at long term care facilities.
Thus far, over 40 residents and staff have experienced symptoms which
primarily include abdominal pain, diarrhea, nausea, and vomiting.
Several residents have either been hospitalized and have visited the
emergency room.
Gastroenteritis while usually self-limited can be extremely debilitating in
fragile elderly populations. If a
facility has a case of acute gastroenteritis, whether it is a resident or
staff-member, it is vital that control measures be implemented quickly and
sustained in order to prevent ongoing transmission.
Links to tools to assist facilities with routine surveillance
for gastroenteritis are found further down on this page. Persons with symptoms
of acute gastroenteritis should be brought to the attention of their healthcare
provider. Clinical specimens should be submitted for laboratory testing as soon
as possible to confirm the cause of the illness. All outbreaks, whether or not a
cause is known, are immediately reportable to the WCCHD at (512) 943-3660.
For more information contact the WCCHD Disease Surveillance Team
at (512) 943-3660 or email Mindy Powell, CDMT Team Lead.
About Norovirus
Noroviruses (formerly known as Norwalk-like viruses) are members of the virus family Caliciviridae. Noroviruses are non-enveloped, making them difficult to eliminate (most disinfectants target an envelope which is missing in these viruses). There are many different strains of circulating Noroviruses. Because of this variability, individuals are likely to be repeatedly infected throughout their lifetimes. Unfortunately, natural immunity is not protective between circulating strains. There are currently no vaccines that offer protection against norovirus.
Illness Signs and Symptoms
Illness begins between one to two days following exposure to a person who is ill or incubating the infection. Unless complicated by underlying illness, age, or dehydration, the illness is generally mild and of short duration (1-2 days). Some individuals may continue to feel weak.
The main symptoms are vomiting and diarrhea. Vomiting, often projectile, is usually a prominent symptom and may be present in at least half of those ill. Diarrhea tends to be watery, short-lived and less severe than diarrhea caused by bacteria. Bloody diarrhea is not a hallmark of Norovirus infection. Other symptoms may also include nausea, headache, fever (usually low-grade), chills, and abdominal cramps.
How is Norovirus Spread?
Noroviruses are spread when material contaminated by stool or vomitus from an infected person is ingested. Noroviruses are
extremely infectious. Excretion of virus in stool begins a few hours before the onset of symptoms and reaches a maximum 24 - 72 hours after exposure. The viruses can continue to be present in the stool of infected persons for a week or more, even after they recover or even if they have never been sick. Noroviruses can remain infectious on environmental surfaces for many days and are relatively resistant to disinfection, heat, and cold. Modes of transmission include person-to-person (fecal/oral, vomit/oral-vomiting will also suspend viral particles in the air resulting in contamination of the environment), fomites (contaminated surfaces), foodborne, and waterborne.
Norovirus Outbreaks
Outbreaks of gastroenteritis in long term care facilities, correctional facilities, and restaurants are not uncommon in Texas or the United States. Noroviruses are most often the culprit and, due to the highly contagious nature of the virus, require immediate attention to prevent prolonged spread of the virus. The Centers for Disease Control and Prevention estimates that 23 million cases of acute gastroenteritis are due to norovirus infection, and that at least 50% of all foodborne outbreaks of gastroenteritis can be attributed to norovirus. Because there are many different circulating Noroviruses and immunity is not protective between circulating strains, Norovirus outbreaks may occur multiple times in the same facility. Norovirus-associated gastroenteritis outbreaks can be detected early by recognizing the typical symptoms of illness, and can be controlled by taking specific infection control steps to prevent the virus from being transmitted from person-to-person. Norovirus outbreaks can be difficult to control because the virus is hardy, multiple modes of transmission may be involved, the infectious dose is low, and decontaminating affected environmental surfaces may be difficult.
Resources
Williamson County & Cities Health District Norovirus Outbreak Detection and
Management Guidance for Long-Term Care Facilities
Recommendations for Long-term Care Facilities and Medical Directors
Public health departments and other government agencies work to limit the impact of norovirus in many different ways:
- Maintain surveillance systems for gastroenteritis to identify outbreaks quickly
- Respond aggressively to outbreaks to limit secondary and tertiary transmission
- Assist long-term care facilities as needed to implement control measures
- Work with food establishments to immediately implement control measures
- Raise awareness of norovirus in the long-term care community, food establishments, and the general public
- Send annual letter to long-term care facilities each Fall reiterating the importance of early detection and laboratory confirmation
- During periods of increased incidence, inform the public through news releases and media outlets
Inform the public of the potential seriousness of norovirus infections for the elderly, the immunocompromised, and others with underlying medical conditions
- Encourage personal cleanliness and hand washing habits
- Ensure restaurants and other food establishments follow basic food safety requirements
- Ensure the safety of municipal water supplies, and effectiveness of sewage treatment
Related Links
Centers for Disease Control Norovirus Website
Texas Department of State Health Services Norovirus Website |
