On November7, 1999,the Center for Disease Control of the Department of Health was informed by the National Cheng Kung University Hospital about four suspected AFP (acute flaccid paralysis) cases. They were students from the same high school who all developed symptoms simultaneously and this thus could be considered to be a clustering of cases in terms of time and place In order to evaluate the nature of the incident for the purpose of disease prevention , the Center for Disease Control dispatched a team on November 8to investigate. After interviewing the individuals concerned and their physicians, it was suspected that the incident was a case of food poisoning caused by the school lunch the students are on November6. An hour after eating the lunch, four students, one after the other developed symptoms of labial ,and facial paralysis, paresis of the neck and limbs, disorientation of movement, drifting feeling, and vomiting One student, the most serious case among them, was semi-conscious upon arrival at the hospital, and was admitted to the intensive care unit. After hemodialysis and supportive treatment, his condition stabilized. In view of their symptoms, treatment, and the menu of the school lunch, the incident was believed to be a food poisoning case caused by tetrodotoxin in the fish fillet of the lunch.