The Incidence of mushroom poisoning was surveyed statistically from 1959 to 1988 in Japan. The results are summarized as follows:
1. During the past three decades, the total number of incidents of mushroom poisoning was 2, 096, which involved 10, 924 patients and 72 deaths. The average number of incidents was 70 cases per year, involving 364 patients and 2.4 deaths, and the number of incidents decreased gradually every year. Mushroom poisoning usually happened most frequently in September and October.
2. Considering regional differences, the incidence of mushroom poisoning was more frequent in the northeastern part of Japan than in the southwestern part. The incidences of mushroom poisoning in the prefectures of Nagano, Hokkaido, Niigata, Iwate and Fukushima were relatively high.
3. Three species of mushrooms, L. japonicus, R. rhodopolius (R. sinuatus) and T. ustale caused the majority of all poisonings.
4. The rates of total patients and fatalities for each type of poisoning, which were classified according to the symptoms caused, were 90.3% and 10.7% in the type with cholera-like symptoms, 90.2% and 0.2% in that with gastro-intestinal irritation, and 74.1% and 0% in that with neurological symptoms, respectively.
