Management of Snakebite and Systemic Envenomation in Rural Ecuador Using the 20-minute Whole Blood Clotting Test

David Gaus, Diego Herrera, Carlos J. Troya, Alicia Guevara


Objectives.—In low-income countries, snakebites are frequently managed in rural areas in health centers with severely constrained resources. Many healthcare providers in these settings have limited access to the numerous and relatively expensive laboratory studies used to diagnose envenomation. The relatively simple and inexpensive 20-minute whole blood clotting test (WBCT) has been recommended by several international organizations for the diagnosis of certain venomous snakebites. This study proposes to confirm the utility of the WBCT as the sole laboratory diagnostic tool to determine systemic envenomation in hematotoxic snakebite management in severely resource-constrained areas of the world.

Methods.—The authors reviewed all 110 cases of snakebite during a 6-year period in a small hospital in rural Ecuador using the WBCT.

Results.—All cases presented within 24 hours of snakebite. Twenty cases revealed normal coagulation with no clinical evidence of systemic envenomation. Ninety cases had no evidence of clot formation (positive WBCT) at 20 minutes, suggesting systemic envenomation. Of these 90 cases, according to a classification scale, 54 were mild, 26 were moderate, and 10 were severe envenomations requiring transfer to tertiary care. All mild and moderate systemic envenomations were successfully treated at the rural hospital. All severe envenomations were treated initially with antivenom before transfer to tertiary care. One patient with severe envenomation died in tertiary care.

Conclusions.—The WBCT was predictive of the presence or absence of systemic envenomation from snakebite in our region. The WBCT guided the successful management of mild and moderate systemic envenomation, and spared patients with no evidence of systemic envenomation from potential side effects of antivenom.

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Kasturiratne A, Wickremasinghe AR, de Silva N, et al. The global burden of snakebite: a literature analysis and modeling based on regional estimates of envenoming and deaths. PLoS Med. 2008;5:e218.

World Health Organization. Neglected tropical diseases: snakebite. Available at: seases/diseases/snakebites/en/. Accessed April 29, 2013.

Theakston RD, Laing GD, Fielding CM, et al. Treat- ment of snake bites by Bothrops species and Lachesis muta in Ecuador: laboratory screening of candidate antivenoms. Trans R Soc Trop Med Hyg. 1995;89: 550–455.

Campbell JA, Lamar WW. The Venomous Reptiles of the Western Hemisphere. Ithaca, NY: Comstock Publishing Associates; 2004:51, 443.

Freire A, Kuch U. A note on the geographical distribution of Bothrops asper (Garman, 1883) in Ecuador. Snake. 1994;26:135–139.

Smalligan R, Cole J, Brito N, et al. Crotaline snake bite in the Ecuadorian Amazon: randomised double blind com- parative trial of three South American polyspecific anti- venoms. BMJ. 2004;329:1129.

Sasa M, Wasko DK, Lamar WW. Natural history of the terciopelo Bothrops asper (Serpentes: Viperidae) in Costa Rica. Toxicon. 2009;54:904–922.

Campbell JA, Lamar WW. The Venomous Reptiles of the Western Hemisphere. Ithaca, NY: Comstock Publishing Associates; 2004:732–733.

Warrell DA, Davidson NMcD, Greenwood BM, et al. Poisoning by bites of the saw-scaled or carpet viper (Echis carinatus) in Nigeria. Q J Med. 1977;46:33–62.

Suero antiofídico polivalente liofilizado Probiol inmuno- globina equina efectiva contra el envenenamiento causado por las mordeduras de serpientes de la familia viperidae de los géneros bothrops (talla x), crotalus (cascabel) y lachesis (verrugoso), [package insert]. Bogotá, Colombia; Laboratorios Probiol; 2005.

Otero Patino R. Accidente ofídico. In: Córdoba D, ed. Toxicología. 2nd ed. México City, México: Manual Moderno; 1991:375–387.

Gawarammana IB, Kularatne SA, Dissanayake WP,

Kumarasiri RP, Senanayake N, Ariyasena H. Parallel infusion of hydrocortisone þ/– chlorpheniramine bolus injection to prevent acute adverse reactions to antivenom for snakebites. Med J Aust. 2004;180:20–23.

de Silva HA, Pathmeswaran A, Ranasinha CD, et al. Low- dose adrenaline, promethazine, and hydrocortisone in the prevention of acute adverse reactions to antivenom following snakebite: a randomised, double-blind, placebo- controlled trial. PLoS Med. 2011;8:e1000435.

Theakston RD, Reid HA, Larrick JW, Kaplan J, Yost JA. Snake venom antibodies in Ecuadorian Indians. J Trop Med Hyg. 1981;84:199–202.

[No authors listed]. WHO/SEARO Guidelines for the clinical management of snake bites in the Southeast Asian region. Southeast Asian J Trop Med Public Health. 1999;30 suppl 1:1–85.

Malasit P, Warrell DA, Chanthavanich P, et al. Prediction, prevention, and mechanism of early (anaphylactic) anti- venom reactions in victims of snake bites. Br Med J (Clin Res Ed). 1986;292:17–20.

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