The Centre for Health Protection (CHP) today said it is investigating the possible source of a norovirus outbreak involving students who had joined an exchange tour to the Mainland.
Yesterday, the CHP 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. During the period from around 11am on March 21 to 8am the next day, 20 students and one teacher developed symptoms compatible with norovirus infection, including vomiting, diarrhoea and fever.
Eighteen patients sought medical attention in Zhaoqing. All are in a stable condition and have been discharged, and eight have tested positive for norovirus.
The CHP is probing the possible source of this norovirus outbreak from different aspects, including the possibility of transmission through person-to-person, contaminated food or the environment. Preliminary investigations revealed that all 21 patients had not consumed any common food items other than the group meals, and there has not been any outbreak of acute gastroenteritis in the school recently.
After analysing the onset time of the cases, the CHP said that it could not, at this stage, preliminarily rule out that the cases were infected through consuming contaminated food.
The centre 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.
Apart from giving health advice to the affected school, the CHP will continue to follow up on the incident and conduct epidemiological investigations, including collecting stool specimens from the cases for laboratory testing. It has also alerted the Education Bureau to the situation.
Separately, the CHP noted that the activity of acute gastroenteritis in Hong Kong 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 there were 57 outbreaks and 49 in February, while up to March 15, a total of 21 outbreak cases were recorded. Most of these outbreaks were caused by the norovirus.
The centre also remarked that in addition to the Mainland, there have been recent outbreaks of acute gastroenteritis in other popular travel destinations for Hong Kong citizens, such as Japan, Singapore and Taiwan.
To minimise the risk of being infected while travelling, the centre advised citizens to remain vigilant and maintain personal, environmental and food hygiene.
