TAIPEI (Taiwan News) — Traces of a deadly toxin have been detected in the digestive tract of the cook at a Taipei restaurant where at least 34 people have fallen ill. 

Deputy Minister of Health and Welfare Victor Wang (王必勝) on Saturday (April 6) said on Facebook that traces of bongkrek acid were not only found on the hands of a substitute Vietnamese cook, but also in stool samples. Wang believes the cook, surnamed Ho (胡), may have inadvertently ingested the toxin when he ate food that had come into contact with his hands.

Wang said all the positive cases had meals at the Malaysian restaurant chain Polam Kopitiam between March 19-24. They had consumed either potstickers or rice noodles. 

Ho's test results were positive for the toxin in his feces, but his blood and biochemical tests were negative, according to Wang. He said the cook's liver functions will continue to be observed for abnormalities.

Wang said that on April 4, investigators visited Ho and the cook from the Raohe branch. Fifteen samples were taken from the Raohe branch cook, and 12 samples were taken from the home of Ho, who worked at the branch in the Far Eastern Sogo Xinyi A13 Department Store.

According to Centers for Disease Control (CDC) statistics, 34 cases have been reported from the Xinyi branch so far, and two at the Raohe eatery. Of the diners sickened at the Xinyi branch, two have died, four remain in intensive care, three are staying in regular hospital wards, and 25 have returned home to recuperate. 

The CDC has expanded its notification criteria to those who dined at either branch from March 17-26 and experienced symptoms of discomfort before March 28.