title: Envenomation by the scorpion Tityus breweri in the Guayana Shield, Venezuela: report of a case, efficacy and reactivity of antivenom, and proposal for a toxinological partitioning of the Venezuelan scorpion fauna.
abstract: OBJECTIVE
  Scorpion envenomation is a common public health problem in Venezuela. We report an envenoming case by Tityus breweri, endemic to the Guayana Shield, southeast Venezuela, and the outcome of its treatment with antivenom anti-Tityus discrepans. Toxin composition and antigenic reactivity of T breweri venom were also explored. T breweri distribution range was re-evaluated.
  
  
  METHODS
  Clinical signs and symptoms in an adult male were recorded after envenoming and treatment with antivenom. Toxin composition and antigenicity of T breweri venom were investigated by polyacrylamide gel electrophoresis, immunoblotting, and mass spectrometry. T breweri distribution range was reassessed by mapping new records of the species.
  
  
  RESULTS
  The moderately severe case (a 21-year-old man) presented autonomic manifestations, including cardiopulmonary and gastrointestinal effects. Full recovery was achieved after anti-T discrepans antivenom administration. T breweri venom contains toxins in the 6-8 kd range that affect voltage-sensitive sodium channels. Based on new records, T breweri distribution area reaches 12 155 km.(2) Inclusion of southeast Venezuela as an endemic area of scorpionism prompted the examination of clinical, immunological, and phylogenetic evidence for suggesting a partitioning of the Venezuelan Tityus fauna into toxinological provinces.
  
  
  CONCLUSIONS
  The severity of the case reinforces categorization of the Guayana Shield region as a macroendemic area of scorpionism in Venezuela and allows classification of T breweri as a species of medical importance, with toxins immunologically related to central-eastern Venezuelan Tityus. Partitioning of the territory incorporating multiple criteria may help health authorities establish and implement preventive and therapeutic measures for scorpion envenoming in this region.
authors.affiliation: Laboratory of Molecular Biology of Toxins and Receptors, Biomembranes Section, Institute of Experimental Medicine, Central University of Venezuela, Caracas, Venezuela. borges.adolfo@gmail.com
authors.forename: Adolfo
authors.initials: A
authors.lastname: Borges
authors.forename: Fernando J M
authors.initials: FJ
authors.lastname: Rojas-Runjaic
authors.forename: Nardy
authors.initials: N
authors.lastname: Diez
authors.forename: José G
authors.initials: JG
authors.lastname: Faks
authors.forename: Huub J M
authors.initials: HJ
authors.lastname: Op den Camp
authors.forename: Leonardo
authors.initials: L
authors.lastname: De Sousa
mesh_terms: D000328:Adult; D000818:Animals; D000997:Antivenins / Q000627:therapeutic use*; D006801:Humans; D006854:Hydrocortisone / Q000627:therapeutic use; D008297:Male; D065008:Scorpion Stings / Q000175:diagnosis* / Q000276:immunology / Q000628:therapy; D012604:Scorpion Venoms / Q000037:antagonists & inhibitors / Q000633:toxicity*; D012605:Scorpions / Q000145:classification / Q000472:pathogenicity*; D014687:Venezuela; D055815:Young Adult
chemical_list: D000997:Antivenins; D012604:Scorpion Venoms; D006854:Hydrocortisone