Epidemiological and Clinical Aspects of Snakebites in Colombia. Severe Bothropic Envenomation.
Otero, Rafael
Departamento de Pediatría y Programa de Ofidismo en Antioquia y Chocó, Facultad de Medicina, Universidad de Antioquia, A.A. 1226, Medellín, Colombia.
In Colombia, 2000 to 3000 snakebites are reported annually, 500 to 700 in Antioquia and Chocó for an adjusted incidence of 21 and 38 cases/100,000 rural inhabitants, respectively. Most of the bites (90 to 95%) are inflicted by Bothrops and Porthidium spp, especially by B. atrox asper (50 to 70%), and P. nasutum (15 to 30%) in northwestern Colombia. The highest incidence occurs in males 15 to 44 years old (53.7%), with bites in the lower limbs (71%) while working in agricultural activities; 28 to 33% in children, 14% at home. Between 50% and 60% of patients seek medical attention more than 6 h after being bitten. They are initially attended by traditional healers and arrive at the hospital with moderate (35 to 40%) or severe (15 to 38%) bothropic envenomation, 12% being then referred to other health institutions due to the lack of antivenoms or complications (16%). Geographical difficulties, insufficient production and supply of antivenoms, and lack of official epidemiological surveillance are also associated with the high mortality rate (5%) and sequelae (6%) from Bothrops bites in the country. The clinical features include: edema (95%), local hemorrhage (34%), blistering (12%), necrosis (10%), defibrination (62%), thrombocytopenia (31%), gingival bleeding (23%), hematuria (25%), hypotension (14%), and other hemorrhage distant from the bite site. Acute renal failure (11%), cellulitis/abscess (11 to 18%), compartment syndrome (3%), hemorrhage in the central nervous system (2 to 3%), and abortion or abruptio placentae may be other complications. Severe envenomation is characterized by non-clottable blood and local necrosis or local swelling extending beyond the bitten limb, local and systemic bleeding, and hypotension or renal failure or central nervous system hemorrhage. After three randomized clinical trials performed in the region using antivenoms from Brazil, Costa Rica, and Colombia, the antivenom doses recommended are 2, 4, and 6 to 9 vials for mild, moderate or severe bothropic envenomation, respectively; the highest dose also when the snake is > 100 cm in length. Ancillary treatment must include the administration of plasma expanders to correct hypovolemia, broad-spectrum antibiotics for all moderate or severe cases, tetanus prophylaxis (second day), and hourly urine output measurement. Additionally, blood platelet and coagulation status monitoring should be performed at 12, 24, 48, and 72 h. One sufficient antivenom dose will totally restore blood coagulation status within 24 h of beginning serotherapy. Bleeding other hematuria must be stopped within the first 6 to 12 h of treatment. By monitoring serum creatinine and electrolyte concentrations and acid-base status may contribute to indicate dialysis in patients with renal failure, in some cases plasma expanders, furosemide (1 to 2 mg/kg) and dopamine infusion (2.5 to 5.0 µg/kg/min) fail. If a compartment syndrome is suspected and the intracompartmental pressure is above 30 mm/Hg, IV administration of mannitol (1 to 2 g/kg over 30 to 60 min) can avoid fasciotomy. Blisters and necrotic skin debridement and amputations are performed 3 to 5 days after the bite; skin grafts and rehabilitation after the second week of treatment.
Publication Dates
-
Publication in this collection
08 Oct 2002 -
Date of issue
Dec 2001
