Thirty-six people at a school in South China's Guangxi Zhuang Autonomous Region have been confirmed to have hepatitis A, and 27 others are showing symptoms of the disease, local health authorities said over the weekend.

Local officials have linked the outbreak to drinking water contaminated by colon bacillus.

Altogether, 111 students and a canteen worker at Fengshan Town No 2 Middle School in Bobai County have been identified as carriers of hepatitis A, said Gong Jian, head of the regional centre for disease control and prevention.

All 112 people have been sent to local hospitals and are in stable condition, according to officials at the Bobai health bureau.

Li Yufeng, a doctor with the Bobai County People's Hospital, said the situation is under control.

However, doctors warned that the number of cases could rise, since the virus has an incubation period of 15 to 30 days, meaning that more people could be infected and not yet be showing symptoms.

The infected students have been separated from their classmates and study in designated classrooms. Uninfected students were required to remain on campus over the weekend for further observation to avoid more infections, officials said.

All of the school's 1,438 students and staff members have been inoculated to contain the spread of the disease, said Xu Zhangneng, director of the county health bureau.

Gong said the first case appeared on November 23, and the outbreak spread on December 6.

Initial investigations suggested that a well that supplies most of the students' drinking water could have been contaminated by a drainage ditch that sits just 5 metres away, said Gong.

Students also wash their faces and brush their teeth with water channelled from nearby mountain springs.

Tests have found high levels of colon bacillus in water taken from the well and the springs, according to Gong.

In addition, living conditions at the school were cramped, with 20 students sharing one room. The school's canteen did not have a health certificate.

Local health authorities have sterilized toilets, the canteen, dormitories and classrooms to prevent further infection.

In August, an outbreak of hepatitis A affected 69 high school students in the same region.

Hepatitis, or inflammation of the liver, is caused by infectious or toxic agents and is characterized by jaundice, fever, liver enlargement, and abdominal pain.

(China Daily December 18, 2006)