Pentastomiasis is also known as tongue worm infestation. The parasites live in the respiratory tract of snakes and other reptiles.

The boy, only identified by given name Weijie, is from Zhejiang Province. Hundreds of parasites were found in his lung, liver, intestines and kidney at Fudan University's Children's Hospital two weeks ago, astonishing even the doctors.

He is in good condition now, but needs time to cleanse his body of the parasites, a doctor said.

"We've never seen such a case," said a pediatrician surnamed Yu, who is taking care of Weijie. "He was so skinny and only weighed 24 kilograms. He vomited a lot when he was sent here."

The boy ate a raw snake gallbladder offered by his parents. They thought a snake gallbladder would keep their son healthy and greatly improve his eyesight - a common belief in the countryside. "This is total nonsense," said Dr Yu. "Eating these raw animal organs may lead the parasites to many organs such as the lungs, heart or brain. It can cause blindness and even death."

Yu also said that frog meat, mutton and seafood can lead to parasites if it is eaten raw or not well-cooked.

Chinese medicine experts said many people ingest a snake gallbladder improperly. Most just swallow the entire snake gallbladder with some liquor as a disinfectant.

"Snake gallbladder is good for eyesight and clearing inner heat. The appropriate way is to parch the gallbladder and make it into a powder," said Meng Siliang, vice secretary-general of the Shanghai Traditional Chinese Medicine Association