In response to media enquiries about a number of students of a secondary school in Tsing Yi developed gastroenteritis symptoms after joining an exchange tour to the Mainland, the Centre for Health Protection (CHP) of the Department of Health responded today (March 23) as follows:
"According to the information provided by the Education Bureau, the CHP yesterday (March 22) learnt of a suspected cluster case of acute gastroenteritis (AGE) in an exchange tour, and immediately commenced an epidemiological investigation. It was learnt that 135 teachers and students from a secondary school in Tsing Yi went on a three-day exchange tour to Zhaoqing on March 20. Subsequently, 20 students and one teacher developed symptoms compatible with norovirus infection, including vomiting, diarrhea, and fever during the period from around 11am on March 21 to 8am the next day. Among them, 18 patients sought medical attention in Zhaoqing. All are in stable condition and have been discharged, and eight have tested positive for norovirus.
The CHP is investigating the possible source of this norovirus outbreak from different aspects, including the possibility of transmission through person-to-person, or contaminated food or environment. Preliminary investigations result revealed that all 21 affected persons had not consumed any common food items other than the group meals and there has not been any outbreak of AGE in the school recently. After analysis of the onset time of the cases, at this stage, the CHP could not preliminarily rule out that the cases were infected by consuming contaminated food. The CHP has notified the Guangdong health authority of the relevant information of epidemiological investigations, and has been informed that the Mainland has commenced investigation into the case.
The CHP has provided health advice to the affected school on the transmission, prevention and infection control measures related to AGE. The CHP will continue to follow up on the incident and conduct epidemiological investigations, including collecting stool specimens from the cases for laboratory testing. The CHP has also alerted the Education Bureau to the situation.
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 been at high level 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 diarrhea outbreaks has remained highest in 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.
Locally, the activity of AGE has been on the rise since the end of December last year and has remained at a relatively high level in recent months. In January and February this year, there were 57 and 49 outbreaks of AGE cases respectively, and in March up to March 15, a total of 21 outbreaks of AGE cases were recorded. Most of these outbreaks were caused by norovirus.
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, 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."
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