There are two families of venomous snakes in the Upper Amazon — the Crotalidae or pit vipers and the Elapidae or coral snakes. The Crotalidae are called pit vipers because they have a pit or depression between the eye and the nostril on each side of the head, which functions as an extremely sensitive infrared heat-detecting organ. In the United States, there are three genera of the Crotalidae family — the copperhead, the cottonmouth or water moccasin, and fifteen species of rattlesnake.
There are also two species of so-called forest pit vipers, in the genus Bothriopsis — the two-striped and the speckled, both exclusively arboreal and camouflaged for tree dwelling, with the color green in their pattern. These forest pit vipers are slender snakes, reaching five feet in length, with prehensile tails, usually found coiled around twigs and bushes.
Whereas the other neotropical pit vipers bear live young, the bushmaster lays eggs. Because of its length, it can strike over a long distance; because of its large fangs, it can deliver a large dose of venom — probably the largest venom dose of any pit viper. However, bushmasters are very reclusive and therefore rarely encountered; many experienced tropical herpetologists have yet to see their first wild specimen. Thus, few envenomations actually occur, although the fatality rate is reportedly high. I have been unable to find information about the age, physical condition, or treatment of reported fatalities. And it is worth adding that envenomation by any of the Elapidae in the Amazon — primarily fifty-three species of coral snakes in the genus Micruris — is apparently very rare as well.
Indeed, many pit viper strikes in fact are dry and inject no venom, even when there are fang marks. The snake may have recently injected venom and not yet replenished; it may be because humans are much bigger and give off a lot more heat than the snake's usual prey, and this throws off the timing of the venom delivery. Additionally, Crotalids can differ significantly in the toxicity of their venom, even within a single litter.
Pit viper envenomation can be excruciatingly painful — one expert has said that, on a pain scale of one to ten, rattlesnake bites are an eleven — and the discomfort can last for several days. The envenomated extremity can also become frighteningly ugly, leading to panic in both the patient and the caregiver. Greater or smaller areas of the extremity can turn blue or black, swell alarmingly, and develop large blood blisters. It is altogether an unpleasant experience. There is no question that a Crotalid envenomation is a medical emergency requiring urgent evacuation if possible. However, the first step in treatment is to avoid panic; even without evacuation, most cases result in several days of serious misery and then recovery. More rarely, skin grafts may be necessary. Remember that the fatality rate even for untreated pit viper bites is extremely low.
Shamans all have their own songs to drive out venom and heal snakebite, usually called, generically, icaro de vibora, pit viper song; remember that icaros generally do not have individual titles in the way that, say, songs do in North America. This icaro is then combined with the definitional triad of mestizo shamanic healing — shacapar, rattling; chupar, sucking; and soplar, blowing tobacco smoke — followed by application of the herbal remedy.
It is hard to judge the effectiveness of any of these remedies. There are few records; there is little long-term follow-up; Crotalid envenomation is frequently self-limiting. There appears to be little empirical basis for allegedly high mortality rates in cases of bushmaster envenomation; a pit viper strike can create a deep puncture wound and severely compromised tissue, so sepsis, especially in the jungle environment, must be a frequent complication. There is evidence that a number of plants traditionally used to treat snakebite — especially those in the family Urticaceae, such as ishanga blanca — have antiinflammatory, immunomodulatory, and thus potentially antivenom activity, which remains to be investigated.