Officials visited Satri Wittaya School and collected varioussamples of food, in particular the stir-fried basil and chicken with fried egg over rice that the students had for dinner on Monday evening. The food has been tested and the results should be known by Wednesday.
Many students attending the annual camp activities from Sunday to Wednesday developed severe diarrhoea, with vomiting and stomach pains. The school called the emergency services and 10 ambulances took the worst affected to Bangkok Metropolitan Administration's General Hospital and Vajira Hospital.
Teenagers with milder symptoms were treated at the school's infirmary.
A Mathayom 5 student, who asked not to be named, said she had developed stomach pains and felt bloated after eating her dinner on Monday and had been suffering from diarrhoea throughout the night.
Many of her friends were also suffering with the same symptoms, she said.
The camp had been attended by high-schoolers aged 16-18 from 96 schools around the country.