NOROVIRUS INFECTION

CAUSATIVE AGENT

This infection is caused by a group of viruses known as noroviruses, also known as "Norwalk-like viruses" or small round structured viruses (SRSVs). These viruses cause sporadic cases of acute gastroenteritis as well as outbreaks of food poisoning and acute gastroenteritis, especially in elderly homes and schools. The disease tends to be more common during winter.

CLINICAL FEATURES

The disease is usually self-limiting with symptoms of nausea, vomiting, diarrhoea, abdominal pain, low-grade fever and malaise. The symptoms usually last for 12 to 60 hours.

• 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.

MANAGEMENT

Give adequate fluids to prevent dehydration and supportive treatment. The disease is usually self-limiting, lasting 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.
• All food, particularly shellfish, should be cooked thoroughly before consumption.
• Food handlers and caretakers developing vomiting or diarrhoea should refrain from work and seek medical advice.
• 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 surfaces promptly and thoroughly with household bleach (5.25%) diluted in a ratio of 1 part of bleach in 49 parts of water. Wash hands thoroughly afterwards.

DISINFECTION OF ENVIRONMENT AFTER VOMITING INCIDENTS

• Keep children away from the area during the cleaning process.
• Wear gloves and a mask while removing the vomitus.
• Use disposable towels to wipe away all the vomitus from outside inward, before applying diluted bleach (1:40) to the surface and the neighbouring area (e.g. within two metres of the vomitus).
• Leave bleach on the soiled surface for about 30 minutes to allow time for the bleach to inactivate viruses before rinsing the surface with water. Leave the surface to dry.
• Floor mops should not be used for cleaning the vomitus.

Centre for Health Protection Website: www.chp.gov.hk
24-Hour Health Education Hotline of the Department of Health 2833 0111.