Beijing's public health authority has traced the sources of the apple snails from south China's Guangxi Zhuang Autonomous Region, which poisoned 131 people in the city, Beijing News said today.

The Amazonian snail, a large freshwater snail, carried angiostrongylus cantonensis, a parasite that can cause meningitis, and passed on the disease when it was served raw in a Sichuan cuisine restaurant in Beijing, the newspaper said.

The restaurant supplier purchased the apple snails from a wholesale market named Yuegezhuang in Guilin, capital city of Guangxi, where the snails originated, said the statement issued by the authority yesterday.

Yuegezhuang once have bought some snails from another local wholesale market, Tianmin market, because of a supply shortage, the statement said.

An investigation into the 85 clinic cases shows that most of the victims can recall the restaurants where they caught meningitis after they ate undercooked or raw apple snails or seafood, including the Sichuan restaurant and another Japanese restaurant near Olympic Village, Gao Xing, a director from the Beijing Health Bureau, told the newspaper.

However, the source of one case among the 85 is harder to trace, as the victim regularly eats raw fish and snails and he couldn't specify which restaurant he dined in before he was sent to the hospital, Gao said.

The municipal health supervision authority is busy collecting the victims' information, which will be the foundation of administrative punishments for the restaurants, he said.

Shanghai halted the sale of the apple snails in two major local aquatic products wholesale markets soon after the food poisoning cases were reported, said a previous report. The municipal food and drug administration said it didn't come across the parasite which causes meningitis in the snails served in local restaurants.

Fishery experts remind the public to not buy shellfish from unlicensed vendors and to never eat raw snails.

(Shanghai Daily September 4, 2006)