The Centre for Health Protection (CHP) of the Department of Health (DH) is today (March 17) investigating a cluster of acute gastroenteritis (AGE) symptoms among six secondary students who participated in an exchange tour to Xiamen last week. In view of the recent high activity of norovirus, the CHP has issued a letter to all schools in Hong Kong to provide health advice on the transmission, prevention and infection control of AGE. The CHP also organised an online meeting for the Education Bureau (EDB) and the service contractors of exchange tours on March 13 to provide health advice on the prevention of communicable diseases and food safety during the trip. The CHP will continue to provide health tips on outbound travel to students, teachers and parents through these service contractors. Furthermore, the CHP has stepped up publicity and education efforts at various boundary control points to remind members of the public to observe hygiene and be vigilant against viral gastroenteritis.
The latest cluster involves a secondary school in Kwun Tong District. A total of 36 teachers and students participated in an exchange tour to Xiamen between March 13 and 15, during which six students developed AGE symptoms, including vomiting, diarrhoea and fever, from about 9pm on March 14 to about 7am the next morning. Five of them sought medical attention in Xiamen, and none required hospitalisation.
The CHP is investigating the source of this AGE outbreak from different aspects. Preliminary epidemiological investigations revealed that all six affected persons had not consumed any common food items other than the group meals and had no other common exposure history in Hong Kong prior to their departure. Hence, at this stage, the CHP could not rule out the possibility that the cases were infected by consuming contaminated food. The CHP has notified the Mainland health authority of the relevant epidemiological investigations and information regarding the restaurants concerned. The CHP is collecting stool specimens from the patients for laboratory testing and has notified the EDB of the relevant assessment.
Regarding the three clusters of students participating in exchange tours to Shaoguan who developed gastroenteritis symptoms earlier, the CHP's follow-up investigation found that three more students developed gastroenteritis symptoms on March 7 and 9 respectively, bringing the total number of affected persons from the previously announced 52 teachers and students to 55. Among them, 16 have sought medical attention, and three have tested positive for norovirus. The CHP will continue to work closely with the Guangdong authority and take necessary follow-up actions.
Apart from the Mainland, there have been recent outbreaks of AGE in other popular travel destinations for Hong Kong citizens. In Japan, the number of patients seeking medical attention for infective gastroenteritis has increased in recent weeks, and large-scale food poisoning outbreaks caused by norovirus have been reported in various places in recent months. In Singapore, the number of medical consultations related to acute diarrhoeal illnesses was higher than the same period last year. In Taiwan, the number of medical consultations related to diarrhoea has remained high in recent months, reaching a record high over the same period in the past five years. Test results showed that the majority of the outbreaks were caused by norovirus. Members of the public should remain vigilant and maintain personal, environmental and food hygiene at all times to minimise the risk of being infected while travelling.
Viral gastroenteritis is more commonly seen in cooler months and can be caused by a variety of viruses, most commonly norovirus and rotavirus. The main symptoms of viral gastroenteritis are diarrhoea and vomiting. Other symptoms include headache, fever, and abdominal cramps. In general, the symptoms begin one to two days following infection with a virus that causes gastroenteritis. Depending on the type of viruses causing the illness, however, the symptoms may last for one to 10 days.
Alcohol-based handrub should not substitute hand hygiene with liquid soap and water, as alcohol does not effectively kill some viruses frequently causing AGE, for example, norovirus. To prevent foodborne diseases, members of the public are advised to observe good personal, food and environmental hygiene. When eating out, the following points should be observed:
- Ensure proper personal hygiene;
- Wash hands thoroughly before handling food and eating, after using the toilet or after changing diapers;
- Wear gloves and surgical mask when disposing of vomitus or faecal matter, and wash hands afterwards;
- Clean and disinfect contaminated areas or items promptly and thoroughly with diluted household bleach (by adding one part of bleach containing 5.25 per cent sodium hypochlorite to 49 parts of water). Wash hands thoroughly afterwards;
- Maintain good indoor ventilation;
- Pay attention to food hygiene;
- Use separate utensils to handle raw and cooked food;
- Avoid food that is not thoroughly cooked;
- Drink boiled water; and
- Do not patronise unlicensed food premises or food stalls.
​The public may visit the CHP's website for more information and preventive advice on viral gastroenteritis.