"It is a type of psychological problem called mass hysteria. It usually affects the young and females and spreads among those who are staying at the same place," Principal of Dhaka Medical College and Hospital (DMCH) and Prof of Medicine MA Foyez said, adding that it usually spreads by seeing or hearing from close quarters.

"The children will be cured soon. It is not an incident of infection and there is nothing to be panicked," said Prof Foyez who is supervising the treatment.

"Fourteen patients, mostly aged between 13 and 16, have been admitted to the DMCH. Ten of them are girls and suffering from headache and a kind of muscle pull. But their neurological and routine examination shows fully normal results. The problem was not due to heat stroke and it should be investigated whether there were any environmental problem in the area," he said.

Four medical teams -- two from the armed forces, one from the Directorate General of Health and one from Narsingdi civil surgeon's office -- are now in Narsingdi to examine the environment and drinking water of the school and nearby areas.

Team members investigating the issue said they started observing the situation from Saturday and it may take several days before they are able to say anything clearly.

A board meeting with ten expert physicians of different disciplines including medicine, psychiatry, neurology, gastroenterology, nephrology, cardiology and others took place at around 9:00am yesterday.

The physicians said there is nothing to be afraid of the unknown disease.

Several patients of the disease have already been cured after treatment at Narsingdi Sadar Hospital and left the hospital, said Shakhawat Hossain, a member of the governing body of Adiabad Islamia High School and College.

“The school has been declared closed for three days and the vacation may increase if necessary, Principal of the institution Nur Shakhawat Hossain said.

When the students started fainting on Wednesday, the school authorities first thought that it might be due to hot weather.

"Thinking so, we arranged taking the classes from 7:30am instead of 10:30am on Saturday. But similar cases took place during the first hour when several students and four teachers fainted," the principal said.

Strangely enough, no one outside the school got senseless or developed the symptoms.

As The Daily Star correspondents talked to the patients, some of them seemed a little bit abnormal.

Class nine student Aleya Akhter, who was admitted to DMCH Saturday morning, said, "It seemed a wind blew towards the classroom through the open window and I felt the smell of a medicine. Suddenly tear started rolling down my cheeks with severe headache and muscle pulling."

Aleya's mother Sharifa Begum said the girl felt breathing problem with chest pain immediately after her returning home from school on Thursday.

The patients' conditions are fluctuating and they are provided with mild tranquilliser, Prof Foyez said, adding, "If the Department of Medicine finds all the test results of the patients' normal, they will refer them to the Department of Psychiatry. They will need counselling."

Last year, such cases took place among the students of a school in Munshiganj and two schools in Faridpur. However, the number of victims was much smaller.