title: Antivenom cross neutralisation in a suspected Asian pit viper envenoming causing severe coagulopathy.
abstract: There is evidence of cross-neutralisation between common toxin groups in snake venoms and therefore the potential for antivenoms to be effective against species they are not raised against. Here we present a 49 year old female bitten by an unknown pit-viper in Nepal. She developed a venom induced consumption coagulopathy with an unrecordable international normalised ratio and undetectable fibrinogen. On return to Australia 5 days post-bite she was treated successfully with one antivenom raised against Malayan pit viper and green pit viper venoms (Haemato-polvalent antivenom from Thailand) and then subsequently with another antivenom raised against American pit-viper venoms (Antivipmyn). Presumed pit viper venom was detected in patient sera with an enzyme immunoassay against Hypnale hypnale venom. There was increased absorbance before antivenom compared to non-envenomed control samples, which then decreased after the administration of each antivenom. The recurrence of venom detected by enzyme immunoassay between antivenom doses was accompanied by a recurrence of the coagulopathy. Cross reactivity between the unknown venom and both antivenoms was supported by the fact that no venom was detected in the pre-antivenom samples after they were incubated in vitro with both antivenoms. This case and investigation of the venom and antivenoms suggest cross-neutralisation between pit vipers, including pit vipers from different continents.
authors.affiliation: School of Medicine and Public Health, University of Newcastle, NSW, Australia; Department of Clinical Toxicology and Pharmacology, Calvary Mater Newcastle, Newcastle, NSW, Australia. Electronic address: geoff.isbister@gmail.com.
authors.forename: G K
authors.initials: GK
authors.lastname: Isbister
authors.affiliation: School of Medicine and Public Health, University of Newcastle, NSW, Australia; Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka.
authors.forename: K
authors.initials: K
authors.lastname: Maduwage
authors.affiliation: Emergency Department, Princess Alexandra Hospital, Brisbane, Queensland, Australia; School of Medicine, University of Queensland, Brisbane, Queensland, Australia.
authors.forename: C B
authors.initials: CB
authors.lastname: Page
mesh_terms: D000997:Antivenins / Q000276:immunology*; D001778:Blood Coagulation Disorders / Q000209:etiology*; D003429:Cross Reactions; D005260:Female; D006801:Humans; D008875:Middle Aged; D009500:Neutralization Tests; D014757:Viper Venoms / Q000276:immunology / Q000633:toxicity*
chemical_list: D000997:Antivenins; D014757:Viper Venoms
keywords: Antivenom; Cross-neutralisation; Pit viper; Snake envenoming; Venom