Wilderness & Environmental Medicine

Wyeth polyvalent crotalid antivenin is the only commercial antivenin available in the United States to treat North American crotalid envenomations. Wyeth antivenin is made from the serum of horses hyperimmunized with four crotalid venoms (Crotalus adamanteus, Crotalus atrox, Crotalus durrisus terrificus, and Bothrops atrox). Although Wyeth antivenin is believed to be effective against all North American crotalids, its efficacy against Agkistrodon contortrix (copperhead) has never been tested. The purpose of this experiment was to determine the efficacy of Wyeth antivenin in the treatment of copperhead envenomation.

Wyeth antivenin was reconstituted in 10 mL of sterile water. In preliminary experiments, 20 mL/kg of Wyeth antivenin administered intraperitoneally prevented death in mice given a lethal subcutaneous injection of Crotalus adamanteus venom. Freeze-dried copperhead venom was reconstituted in sterile water, and a dose-lethality curve for subcutaneous venom was constructed using seven groups of 10 mice each. The endpoint was survival at 24 hours. A dose that is lethal in 90% of the animals receiving it (LD90) was estimated from this curve. Thirty mice were randomly given pretreatment with 20 mL/kg Wyeth antivenin administered intraperitoneally or an equal volume of normal saline as a control. Thirty minutes later, all mice received an LD90 subcutaneous injection of copperhead venom. Lethality was determined at 24 hours.

Following the injection of copperhead venom, none of the 15 control mice and 14 of 15 treatment mice survived until 24 hours (p < 0.001).

Wyeth antivenin is effective in treating copperhead envenomation in mice and may therefore be expected to be effective in humans.

To describe the demographic characteristics and patterns of death of persons killed in snow avalanches over a 45-year study period.

The national avalanche database was the source of data in this retrospective, descriptive study.

A total of 440 victims were killed in 324 fatal avalanches, of which 87.7% were fully buried, 4.7% were partially buried, and 7.6% were not buried. The average age was 27.6 ± 10.6 years, and 87.3% were men. Victims who died included climbers (25.5%), backcountry skiers (22.7%), out-of-bounds skiers (10.0%), snowmobilers (6.8%), in-bounds skiers (5.2%), residents (4.5%), ski patrollers (3.6%), workers (3.6%), and motorists (3.0%). Over the 45-year study period there appear to be decreases in the deaths of in-bounds skiers, highway workers, and motorists. Increasing fatalities were observed among out-of-bounds skiers, snowmobilers, ski patrollers, and backcountry skiers. Most deaths occurred in Colorado (33.0%), Washington (13.2%), and Alaska (12.0%).

Avalanche fatalities have increased over the last 45 years. Climbers, backcountry skiers, out-of-bounds skiers, and more recently snowmobilers constitute the majority of the victims. The decrease in deaths among groups that benefit from avalanche control programs supports the benefit of avalanche prevention strategies. Further study is needed to assess the impact of avalanche safety education for individuals who travel in remote and uncontrolled terrain.