Guo-Qing Shi 1 , Wen-Li Huang 2 , Jian Zhang 3 , Hong Zhao 3 , Tao Shen 1 , Robert E. Fontaine 1 , 4 , Lin Yang 2 , Su Zhao 2 , Bu-Lai Lu 1 , Yue-Bing Wang 2 , Lin Ma 2 , Zhao-Xiang Li 2 , Yang Gao 1 , Zhu-Liang Yang 5 , Guang Zeng 1 , *
17 May 2012
Since the late 1970's, time-space clusters of sudden unexplained death (SUD) in northwest Yunnan, China have alarmed the public and health authorities. From 2006–2009, we initiated enhanced surveillance for SUD to identify a cause, and we warned villagers to avoid eating unfamiliar mushrooms.
We established surveillance for SUD, defined as follows: sudden onset of serious, unexplained physical impairment followed by death in <24 hours. A mild case was onset of any illness in a member of the family or close socially related group of a SUD victim within 1 week of a SUD. We interviewed witnesses of SUD and mild case-persons to identify exposures to potentially toxic substances. We tested blood from mild cases, villagers, and for standard biochemical, enzyme, and electrolyte markers of disease.
We identified 33 SUD, a 73% decline from 2002–2005, distributed among 21 villages of 11 counties. We found a previously undescribed mushroom, Trogia venenata, was eaten by 5 of 7 families with SUD clusters compared to 0 of 31 other control-families from the same villages. In T. venenata–exposed persons SUD was characterized by sudden loss of consciousness during normal activities. This mushroom grew nearby 75% of 61 villages that had time-space SUD clusters from 1975 to 2009 compared to 17% of 18 villages with only single SUD (p<0.001, Fisher's exact test).