Some 30 people have been infected with cholera in Mengcheng county, East China's Anhui province, since Aug 16, most after eating at local street food stalls, local health authorities said.

Over the weekend, 20 of the patients were still receiving treatment in hospital and the rest had been discharged after making a full recovery, according to the local government. No one has died from the disease so far.

"The outbreak, as medical experts said, was related to unclean food and drinks, but they are still looking for the exact source of the mass infection," Shao Junqiang, of the county's information department, said on Sunday afternoon.

Almost all of the patients had eaten cold dishes at food stands before exhibiting symptoms of the infection, such as diarrhea and vomiting, he said.

Cholera is a severe bacterial infection, which can lead to death if it is not treated in a timely manner. In China, it is categorized as a type A infection together with the plague.

Last year, China reported 85 cases of cholera on the mainland, a decrease of almost 50 percent on 2008.

The provincial government arranged for medical experts to be sent to the county to assist treating patients, as well as to keep the outbreak from spreading further.

A member of staff at the Mengcheng No 1 Hospital said that 70 to 80 percent of the patients they handled showed symptoms of intestinal infections and would be quarantined. The hospital is designated to treat intestinal disorders between May and October, the peak season for intestinal outbreaks, he said.

More health professionals had been dispatched by local disease control and prevention centers over the weekend to look for more suspected cases in the county.

All schools and kindergartens were ordered not to start school until Sept 1 to allow the water supply and student canteens to be sanitized beforehand.

The availability of cold dishes on street food stalls has been banned in the county and many stands have closed due to the outbreak.