The Centre for Health Protection (CHP) on Tuesday said it is investigating a cluster of gastroenteritis involving 52 teachers and students who participated in exchange tours to Shaoguan in Guangdong province earlier this month.
They developed symptoms from March 3 to 10. Sixteen of them sought medical attention though none required hospitalisation.
The CHP said the teachers and students – from three secondary schools – had dined at the same restaurants.
It said some of them may have been infected by eating contaminated food, while others may have contracted gastroenteritis through person-to-person transmission or a contaminated environment.
The CHP has notified authorities in Guangdong of the restaurants involved.