Neutralization of Latrodectus mactans and L.hesperus venom by redback spider (l.hasseltii) antivenom

Objective: To test the effectiveness of L. hasseltii (redback spider) antivenom in neutralizing the lethal effects of L. hesperus and L. mactans(North American black widow) venoms. Methods: LD50 values for the L. hesperus and L. mactans venom preparations were determined. A prospective, randomized, double-blind antivenom efficacy experiment was then performed for each venom using a mouse envenomation model. The following treatments were premixed and incubated at 25°C for 1 hour prior to intraperitoneal injection: 1) saline control + protein control, 2) saline control + L. hasseltii antivenom, 3)L. hesperus or L. mactans venom + protein control, and 4) L. hesperus or L. mactans venom + L. hasseltii antivenom. The study endpoints were time elapsed until death and survival at 24 hours. Results: The mouse LD50 values for L. hesperus and L. mactans venoms were 0.64 mg/kg and 0.26 mg/kg, respectively. In the efficacy trial, all mice in group 3 (L. hesperus or L. mactans venom and protein control) died. In both ...