Preplanned Studies: Mushroom Poisoning Outbreaks — China, 2023

Mushroom poisoning in China has emerged as a significant food safety concern. Over the past decade, the government, CDCs, hospitals, and mycological researchers have collaborated to establish a comprehensive network for collecting information on mushroom poisoning, facilitating diagnosis, and providing treatment support. This network utilizes various communication methods such as WeChat, telephone, and email (1-4). Following an incident of mushroom poisoning, CDC staff and hospital professionals promptly collect mushroom specimens and photos, which are then sent to mycologists for identification based on morphological and molecular evidence. In parallel, toxin detection is performed on both the mushrooms and biological samples such as blood and urine. By combining the results from species identification, toxin detection, and clinical manifestations, patients are accurately diagnosed and treated in a timely manner (1-4). In 2023, the China CDC conducted an investigation into 505 incidents of mushroom poisoning across 24 provincial-level administrative divisions (PLADs). This resulted in 1,303 patients and 16 deaths, corresponding to a case fatality rate of 1.23%. A total of 97 poisonous mushroom species, including 12 newly recorded ones, leading to 6 distinct clinical manifestations, were successfully identified. This brings the cumulative number of mushroom species involved in poisoning incidents in China to approximately 220 by the end of 2023.

In 2023, there were multiple incidents of mushroom poisoning, with the number of cases per incident ranging from 1 to 15 and an average of 2. Out of these incidents, only 6 involved more than 10 patients. Among the cases, 23 patients from 11 incidents consumed poisonous mushrooms purchased from markets, while 23 patients from 9 incidents were poisoned after consuming dried mushrooms. Additionally, 217 patients and 5 deaths resulted from 70 incidents where individuals consumed mixed wild mushrooms either self-collected or purchased from markets (Supplementary Table S1).

The temporal distribution analysis revealed that cases of mushroom poisonings were reported throughout the year, with the highest frequency observed between May and October (461 incidents, 1,207 patients, and 15 deaths), reaching a peak in June (127 incidents, 342 patients, and 3 deaths). The first death occurred in late April in Hunan Province. The months with the highest number of deaths were May (7 deaths), followed by June (3 deaths), and August (2 deaths) (Figure 1).

Figure 1. 

Monthly distribution of mushroom poisonings in China in 2023.

In terms of geographical distribution, mushroom poisoning incidents were reported in 24 PLADs. Among these, 12 PLADs had more than 10 incidents. The PLADs of Hunan, Yunnan, Guizhou, Sichuan, and Hubei were the top 5 affected regions. Hunan had 116 incidents with 223 patients and 1 death, followed by Yunnan with 81 incidents, 225 patients, and 1 death, Guizhou with 72 incidents, 231 patients, and 1 death, Sichuan with 48 incidents and 134 patients, and Hubei with 35 incidents and 69 patients (Table 1). Out of the 24 PLADs, 14 had more than 20 patients, with Guizhou, Yunnan, and Hunan having over 200 patients each (Table 1). Regarding fatalities, Guangdong, Guangxi, and Chongqing were the top 3 PLADs, with 5, 4, and 2 deaths, respectively (Table 1).

In 2023, a total of 97 species of poisonous mushrooms were identified in mushroom poisoning cases, leading to 6 distinct clinical syndromes. Among these species, 12 were newly discovered as poisonous in China (Supplementary Table S1). Specifically, Collybia subtropica, Russula brevispora, R. flavescens, and R. pseudojaponica were four newly described species in China in 2023 (5-6). Collybia subtropica contained muscarine and caused stimulation of the parasympathetic nervous system, while the last three species caused gastroenteritis. Collybia subtropica affected 3 individuals in Hunan from early October to mid-November. Russula brevispora was involved in 3 incidents affecting 5 patients, either on its own or in combination with other mushrooms, from June to July in Hunan. Russula flavescens was responsible for 2 incidents involving 4 patients from late August to early November in Yunnan. Russula pseudojaponica caused 17 incidents, affecting 65 patients, from early June to early November in various regions of China, including South, Southwest, Central, and East China. Additionally, three other newly recorded poisonous mushrooms in China that caused gastroenteritis were Coprinopsis strossmayeri, Gymnopus dysodes, and G. similis. Coprinopsis strossmayeri affected 2 patients in Jiangsu in June. Gymnopus dysodes affected 3 patients in June in Yunnan. Gymnopus similis was involved in 2 incidents affecting 3 patients in April and July in Hunan. Moreover, Amanita collariata, Inocybe amelandica, Pseudosperma conviviale, P. triaciculare, and P. ushae were newly described species causing psycho-neurological disorders in Eurasia after 2020 (7-11). Amanita collariata, discovered in Central China in 2022 (7), caused 1 incident involving 4 patients in April in Guangxi, 2023. Inocybe amelandica, originally discovered in the Netherlands in 2020 (8), was involved in 1 incident along with Pseudosperma umbrinellum, P. arenarium, and I. serotina (which contain muscarine) in early October in Ningxia, 2023, affecting 2 patients. Pseudosperma conviviale, discovered in Italy in 2020 (9), caused 1 incident involving 2 patients in early October in Anhui. Pseudosperma triaciculare, discovered in Pakistan in 2020 (10), caused 1 incident involving 2 patients in mid-September in Beijing. Lastly, Pseudosperma ushae, discovered in Germany in 2022 (11), caused 1 incident involving 2 patients in early October in Jilin, together with Cortinarius saturninus.

The three most deadly mushrooms were identified as Amanita fuligineoides, A. subpallidorosea, and Russula subnigricans, causing 7, 2, and 2 deaths respectively (Supplementary Table S1). Among them, Chlorophyllum molybdites was found to have the widest distribution, being discovered in 12 PLADs. This mushroom was also associated with the highest number of poisoning incidents, appearing in 150 incidents and affecting 303 patients. Additionally, it had the longest active period, spanning from early April to early November.

In 2023, a total of 7 species of Amanita, 1 species of Galerina, and 1 species of Lepiota were identified as the cause of acute liver failure in China (Supplementary Table S1). Among these, Amanita fuligineoides was found to be the most dangerous, resulting in 7 deaths in 2 incidents involving 18 patients. Another incident involving Amanita subpallidorosea and A. subfuliginea caused 2 deaths. Additionally, Amanita exitialis, A. subjunquillea, and Galerina sulciceps each caused 1 death. The three most lethal mushroom species responsible for the highest number of incidents were Amanita exitialis (10 incidents, 21 affected patients, and 1 death), Lepiota brunneoincarnata (9 incidents and 29 affected patients), and Amanita subjunquillea (7 incidents, 23 affected patients, and 1 death).

Three species, namely Amanita oberwinklerana, A. pseudoporphyria, and A. kotohiraensis, were identified as the causes of acute renal failure in 2023 (Supplementary Table S1). Amanita oberwinklerana was the most prevalent species, present in 13 incidents involving 26 patients, either alone or in combination with other species. Amanita pseudoporphyria resulted in 2 fatalities out of 5 incidents and affected a total of 17 patients.

Russula subnigricans caused 14 cases of rhabdomyolysis, affecting a total of 38 patients and resulting in 2 fatalities, either on its own or in conjunction with other mushroom species. Additionally, Cordierites frondosus caused photosensitive dermatitis in 4 patients across 2 separate incidents in Yunnan during June (Supplementary Table S1).

A total of 50 mushroom species causing gastroenteritis were identified in China in 2023 (Supplementary Table S1). Among these species, 6 were newly identified as poisonous mushrooms and have been added to the Chinese poisonous mushroom list (1-4). The three most commonly encountered species in this category were Chlorophyllum molybdites, Entoloma omiense, and Russula japonica.

In 2023, a total of 33 mushroom species associated with psycho-neurological disorders were identified in China (Supplementary Table S1) (1). The three most frequently encountered species were Amanita sychnopyramis f. subannulata, which was involved in 10 incidents and affected 30 patients either alone or in combination with other species, followed by Amanita subglobosa, found in 9 incidents and affecting 40 patients, and Psilocybe cubensis, observed in 8 incidents and impacting 27 patients.