Preplanned Studies: Mushroom Poisoning Outbreaks — China, 2022

Mushroom poisoning has become a serious food safety issue in China. With the support of the government, over the past decade, China has gradually established a mushroom poisoning prevention and treatment system involving experts in disease prevention and control, clinical diagnosis and treatment, fungal classification, and basic medicine (1-3). In recent years, a mushroom-poisoning information collecting, diagnosis, and treatment support network has been established, utilizing WeChat, telephone, email, and other methods. After poisoning incidents occur, mushroom samples are collected by CDC staff or hospital professionals and sent to mycological researchers at universities and institutions for identification, based on morphological characters and DNA sequence data (1-3).

In 2022, China CDC investigated 482 mushroom poisoning incidents involving 1,332 patients and 28 deaths, with a total case fatality rate of 2.1%. The number of cases per incident ranged from 1 to 28, with an average of 2. A total of 13 incidents involved more than 10 patients. Of these cases, 73 patients from 23 incidents ate poisonous mushrooms purchased from markets or given by friends; 9 patients from 6 incidents were poisoned after eating raw Chlorophyllum molybdites, Boletus bainiugan, and Macrocybe gigantea, although the last two species were considered to be edible after proper cooking (Supplementary Table S1); 44 patients from 7 incidents were poisoned after eating dried mushrooms; and 213 patients and 3 deaths from 55 incidents ate mixed mushrooms.

The temporal distribution shows that mushroom poisonings occurred in all months, with the highest number of incidents occurring between May and November (460 incidents, 1,234 patients, and 22 deaths). The first death occurred in mid-February in Fujian. The top 3 months for deaths were June (13 deaths), July (3 deaths), and September (3 deaths) (Figure 1).

Figure 1. 

Monthly distribution of mushroom poisonings in China, 2022.

In terms of geographical distribution, mushroom poisoning incidents were reported in 21 provincial-level administrative divisions (PLADs). Overall, 10 PLADs had more than 10 incidents, and Yunnan, Hunan, Sichuan, Guangxi, Chongqing, and Zhejiang were the top 6 (Table 1); 11 PLADs had more than 20 patients, and Yunnan, Hunan, Sichuan, and Guangxi had over 100 patients each (Table 1). Yunnan, Hunan, and Guangdong were the top 3 PLADs in terms of deaths, with 9, 7, and 5 deaths, respectively (Table 1). Southwest China (Yunnan, Sichuan, Chongqing, and Guizhou) was the most severely affected region, with 234 incidents, 703 patients, and 13 deaths. This was followed by Central China (Hunan, Hubei, and Henan) with 109 incidents, 277 patients, and 8 deaths; East China (Zhejiang, Fujian, Jiangsu, Jiangxi, Anhui, and Shanghai) with 55 incidents, 132 patients, and 1 death; South China (Guangxi and Guangdong) with 49 incidents, 152 patients, and 5 deaths; Northwest China (Ningxia) with 19 incidents, 29 patients, and 0 deaths; North China (Shandong, Hebei, and Shanxi) with 14 incidents, 32 patients, and 1 death; and Northeast China (Liaoning and Heilongjiang) with 2 incidents, 7 patients, and 0 deaths. Detailed information for each PLAD is presented in Table 1.

In 2022, 98 species of poisonous mushrooms were successfully identified from mushroom poisoning events, resulting in seven different clinical syndromes. Among these 98 species, 13 were newly recorded as poisonous species in China. Collybia humida nom. prov., Spodocybe venenata nom. prov., and Omphalotus yunnanensis nom. prov. represented 3 undescribed species. The first two species contained muscarine and stimulated the parasympathetic nervous system, while the last species caused gastroenteritis. Coprinopsis aesontiensis and Leucoagaricus purpureolilacinus species complex were two new records in China causing gastroenteritis. The eight remaining species, previously of unclear edibility, were confirmed to be poisonous based on poisoning incidents. These species were Tricholoma olivaceum, a species originally discovered in China and causing gastroenteritis (4); Candolleomyces yanshanensis, Anthracoporus holophaeus, Anthracoporus nigropurpureus, Inocybe cf. assimillata, Inocybe aff. decemgibbosa, Inocybe aff. pseudoreducta, and Inosperma cf. gregarium, which caused psycho-neurological disorders (5-6).

The top three lethal mushroom species were Amanita exitialis, A. rimosa, and Russula subnigricans, which caused 7, 7, and 6 deaths, respectively (Figure 2, Supplementary Table S1). Chlorophyllum molybdites, the most widely distributed mushroom (discovered in 16 PLADs), caused the most poisonings incidents (appearing in 114 incidents and affecting 257 patients) and had a distinct long active period (from early April to early December).

Figure 2. 

Poisonous mushrooms identified from mushroom poisoning incidents in China in 2022.

Note: 1: Amanita exitialis; 2: A. fuliginea; 3: A. fuligineoides; 4: A. rimosa; 5: A. subfuliginea (provided by Yalin Zhou); 6: A. subjunquillea; 7: A. pallidorosea; 8: Galerina sulciceps; 9: Lepiota brunneoincarnata; 10: Russula subnigricans; 11: A. neoovoidea; 12: A. oberwinklerana; 13: A. pseudoporphyria; 14: Paxillus orientalis; 15: Cordierites frondosus; 16: Chlorophyllum molybdites; 17: Russula japonica; 18: Scleroderma cepa (provided by Tianhong Li); 19: Coprinopsis aesontiensis (provided by Wensong Chen); 20: Leucoagaricus purpureolilacinus species complex (provided by Xia Rong); 21: Omphalotus yunnanensis nom. prov.; 22: Tricholoma olivaceum; 23: Lanmaoa asiatica (provided by Guanliang Wen); 24: Gymnopilus dilepis (provided by Ya’an CDC); 25: Anthracoporus nigropurpureus; 26: Amanita rufoferruginea; 27: A. sychnopyramis f. subannulata (provided by Zuohong Chen); 28: Anthracoporus holophaeus (provided by Yanchun Li); 29: Collybia humida nom. prov.; 30: Spodocybe venenata nom. prov.

In 2022, nine species causing acute liver failure were identified in China (Figure 2, Supplementary Table S1). Amanita exitialis was the most dangerous species, causing 7 deaths in 14 incidents involving 41 patients. Amanita rimosa and Galerina sulciceps caused seven and three deaths, respectively. Amanita subfuliginea, a lethal species originally described from Guangdong in 2016 (7), was also identified. On May 29, two people from Chongqing were poisoned by a gray amanita mushroom, marking the first reported poisoning incident since the mushroom was described and the first record of this gray poisonous amanita in Southwest China (7).

Three species of mushroom were identified as causing acute renal failure in mushroom poisoning incidents (Figure 2, Supplementary Table S1). Amanita pseudoporphyria was the most common, appearing in 12 incidents either alone or in combination with other species. Amanita neoovoidea had the longest active period, occurring from mid-June to early November.

Russula subnigricans was linked to 15 incidents of rhabdomyolysis, involving 44 patients and resulting in 6 deaths, either alone or in combination with other mushroom species. This species was found in Yunnan, Hunan, and Zhejiang from June to September. The first Paxillus orientalis poisoning incident from China, resulting in hemolysis, occurred in Sichuan in early June (Figure 2, Supplementary Table S1).

A total of 51 species causing gastroenteritis were identified from mushroom poisoning incidents in China in 2022 (Supplementary Table S1). Among them, four species were identified as poisonous mushrooms and subsequently added to the Chinese poisonous mushroom list (1-3,8). Omphalotus yunnanensis nom. prov. was discovered from a poisoning incident in Yunnan. The top three species in this category were Chlorophyllum molybdites, Russula japonica, and Scleroderma cepa (Figure 2).

In 2022, 32 species of mushrooms causing psycho-neurological disorders were identified in China (Supplementary Table S1). Nine of these species were newly discovered as poisonous (1-3,8), including Collybia humida nom. prov. and Spodocybe venenata nom. prov., which need to be formally described. The top five species were Lanmaoa asiatica, Gymnopilus dilepis, Anthracoporus nigropurpureus, Amanita rufoferruginea, and Amanita sychnopyramis f. subannulata (Figure 2).

On September 30, five Burmese workers in Dehong, Yunnan were poisoned by Inosperma hainanense, a newly discovered species containing muscarine that was identified in Hainan in 2021 (9).