Jararaca

In the mid-1960s, the pharmacologist Sergio Ferreira, working on jararaca venom, isolated substances he called bradykinin-potentiating factors, which he showed strongly lowered blood pressure. Researchers, including teams at the Squibb company, worked out that these venom peptides act by blocking angiotensin-converting enzyme, or ACE, a key controller of blood vessel constriction and fluid balance. One venom peptide was developed into an injectable drug, and then chemists designed an orally active version, captopril, which reached patients in 1981. It was the first ACE inhibitor, and drugs in that class, and the closely related angiotensin-receptor blockers, are now among the most prescribed medicines in the world, used for high blood pressure, heart failure, and kidney disease.

It is a serious envenoming and needs hospital treatment, but it is rarely fatal where antivenom is available. The venom is mainly tissue-destroying and blood-affecting. A bite produces severe pain, rapid swelling, bruising, blistering, and sometimes death of tissue at the site that can require surgery or, in bad cases, cost part of the limb, along with clotting problems that can cause bleeding elsewhere in the body. Brazil produces jararaca antivenom on a large scale and distributes it through the public health system, and with prompt treatment most people recover, though the bitten limb may take a long time to heal and can be permanently affected.

Geography and habitat. The jararaca is abundant in exactly the parts of Brazil where the most people live and farm, the humid southeast, and it thrives in coffee and banana plantations, sugarcane, pasture, and forest edges rather than only in remote wilderness. It is well camouflaged among leaf litter, active at dusk and after dark, and it will hold its ground and strike if trodden on or reached toward. Agricultural workers, especially those harvesting crops by hand without boots, account for most bites. It is not aggressive; it is simply common, cryptic, and living where people work.

The golden lancehead is a close relative, Bothrops insularis, found only on one small island, Ilha da Queimada Grande, off the coast of Sao Paulo. It descended from mainland jararacas that were cut off when sea levels rose, and on the island, with no ground mammals and a diet of migratory birds that would fly away if not killed instantly, it evolved venom several times more potent than the jararaca's. The island holds one of the densest snake populations anywhere and is closed to visitors except for permitted researchers, which has fed a great deal of exaggerated lore, much of it under the nickname Snake Island.