Close to 150 students and faculty at a middle school in central China's Hunan Province have fallen ill due to catching a strand of norovirus or "stomach flu", officials with the provincial health department announced Wednesday.

The patients, including 145 students, two teachers and two other staff members at the school, are all receiving medical care at Changsha's Fourth Hospital, according to the department.

The hospital has activated a special call comprised of 19 doctors specially to look after the patients, it was revealed.

The first norovirus infection at the school occurred on March 6, after a 16-year-old girl was hospitalized, suffering from vomiting, diarrhea and nausea, according to the provincial disease prevention and control center.

The school, which hosts 5,225 students and over 400 teachers and staff members, has halted all water supplies, both through coolers and taps. It has ordered a thorough cleansing of all boilers, pipes and pools, while conducting a complete disinfecting of its buildings and grounds.

The source of the infection is being investigated by Changsha's disease prevention and control authority.

Norovirus is a common gastrointestinal virus which induces nausea, diarrhea, vomiting and abdominal cramps. Symptoms usually appear within 24 to 48 hours of exposure, with a cycle of between one to three days.

In the fall of 2006, a seeming pandemic of norovirus infections racked Japan, Singapore and Italy, with 357,600 people falling ill in under two months.

(Xinhua News Agency March 15, 2007)