| 8 February 2010 |
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Norovirus Infection
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Causative agent
Norovirus infection typically causes acute gastroenteritis. It is also a common cause of food poisoning and is usually related to consumption of undercooked shellfish. Norovirus can also cause outbreaks of acute gastroenteritis in settings where people are staying close together such as schools, elderly homes, hotels and cruise ships. The disease affects people of all age groups and tends to be more common during winter. The virus is previously known as "Norwalk-like viruses".
Clinical features
The disease is characterised by nausea, vomiting, diarrhoea, abdominal pain, low-grade fever and malaise. The symptoms are usually self-limiting and last for 12 to 60 hours.
Modes of transmission
The infection can be transmitted via the following ways:
- by food or water contaminated with the virus;
- by contact with vomitus or faeces from infected persons;
- by contact with contaminated objects; or
- by aerosol spread with contaminated droplets of splashed vomitus.
Incubation period
The incubation period is usually 24 to 48 hours.
Management
Given adequate fluids to prevent dehydration and supportive treatment, the patient usually recovers within one to three days. Antibiotics are of no value in treatment.
Prevention
- Maintain high standards of personal, food and environmental hygiene.
- Wash hands before handling food and eating, and after going to toilet.
- Cook all food, particularly shellfish, thoroughly before consumption.
- Refrain from work or school, and seek medical advice if one is suffering from vomiting or diarrhoea.
- Cleanse vomitus / faeces and disinfect the contaminated areas properly and immediately (please refer to the guidance on disinfection below for details). Keep other people away from the contaminated areas during cleansing.
- Wear gloves and a mask while disposing of or handling vomitus and faeces, and wash hands thoroughly afterwards.
- Clean and disinfect soiled linens, clothes and environmental surfaces promptly and thoroughly with 1 in 49 diluted household bleach (mixing 1 part of household bleach containing 5.25% sodium hypochlorite in 49 parts of water). Wash hands thoroughly afterwards.
- No vaccine is available for norovirus infection.
Guidance in disinfection of area contaminated by vomitus / faecal spillage from patients with norovirus infection
- Keep other people away from the contaminated area.
- Wear gloves and a mask throughout the disinfection procedure.
- Discard all food if vomiting and diarrhoea occurs in an area where open food is displayed.
- Remove the bulky waste cautiously from all soiled linens and clothing before washing. Then, soak them in 1 in 49 diluted household bleach (mixing 1 part of household bleach containing 5.25% sodium hypochlorite in 49 parts of water) for 30 minutes and then wash thoroughly. If immediate washing cannot be arranged, place the soiled linens and clothing inside sealed bags and wash them as soon as possible.
- Use disposable towels to wipe away all the vomitus / faecal spillage from outside inward. Then apply 1 in 49 diluted household bleach (mixing 1 part of household bleach containing 5.25% sodium hypochlorite in 49 parts of water) to the contaminated surface and the adjacent areas liberally (as a rough guide, preferably disinfect areas within 2 metres from the edge of the vomitus / faecal spillage), especially the frequently touched surfaces e.g. door knobs, hand rail.
- Leave bleach on the soiled surface for 15 to 30 minutes to allow time for the bleach to inactivate viruses. Then rinse the surface with clean water. Leave the surface air dry.
- Never use floor mops for cleaning up the vomitus.
- Soak all cleaning tools in 1 in 49 diluted household bleach (1 part of household bleach containing 5.25% sodium hypochlorite in 49 parts of water) for 30 minutes and then rinse thoroughly before reuse.
- Wash hands thoroughly afterwards.
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