title: Clusters of sudden unexplained death associated with the mushroom, Trogia venenata, in rural Yunnan Province, China.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  Epidemiologic data has implicated T. venenata as a probable cause of clusters of SUD in northwestern Yunnan Province. Warnings to villagers about eating this mushroom should continue.
authors.affiliation: Chinese Field Epidemiology Training Program, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Shi
authors.forename: Wen-Li
authors.initials: WL
authors.lastname: Huang
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Zhao
authors.forename: Tao
authors.initials: T
authors.lastname: Shen
authors.forename: Robert E
authors.initials: RE
authors.lastname: Fontaine
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Su
authors.initials: S
authors.lastname: Zhao
authors.forename: Bu-Lai
authors.initials: BL
authors.lastname: Lu
authors.forename: Yue-Bing
authors.initials: YB
authors.lastname: Wang
authors.forename: Lin
authors.initials: L
authors.lastname: Ma
authors.forename: Zhao-Xiang
authors.initials: ZX
authors.lastname: Li
authors.forename: Yang
authors.initials: Y
authors.lastname: Gao
authors.forename: Zhu-Liang
authors.initials: ZL
authors.lastname: Yang
authors.forename: Guang
authors.initials: G
authors.lastname: Zeng
mesh_terms: D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D006801:Humans; D009145:Mushroom Poisoning / Q000453:epidemiology / Q000401:mortality*; D011159:Population Surveillance; D012424:Rural Population