Dark Banquet - Bill Schutt [23]
Primarily because of its antihemostatic properties, vampire bat saliva has drawn considerable attention from the medical community as a potential treatment for certain strokes, namely, those in which a blood clot inhibits blood flow within the brain’s blood vessels. In these instances, cells in the region of the brain on the downstream side of the clot are denied oxygen and nutrients. If this blockade continues for long enough, the cells die and the function they were responsible for is impaired. Traditionally, stroke victims have been treated with a compound called tissue plasminogen activator (t-PA). Unfortunately, t-PA must be administered within three hours of the stroke to be effective. After that, the risk of bleeding into the brain increases, and as a result so does brain cell death. Since the average stroke patient waits more than twelve hours before going to the emergency room, t-PA is rarely administered and cannot be considered an effective treatment for the nation’s third-largest killer (after heart disease and cancer). Unlike t-PA, though, studies have shown that the vampire bat–derived DSPA (an extremely potent clot buster) can be administered up to nine hours after a stroke has occurred and has no detrimental effects on brain cells.
Since vampire bats often lick the site before inflicting their bite, there has also been some speculation that their saliva might contain either a pain-killing agent that prevents their prey from feeling the bite, or an enzyme that could function to soften up the potential bite site. Even without a painkiller or a skin-softening enzyme, the vampire bat’s razor-sharp teeth are likely capable of producing a wound that causes little or no pain to the prey.
In what amounts to a strange sort of payback, one modern technique used for vampire bat eradication involves the use of the anticoagulant warfarin. Isolated from a clover mold, warfarin has been marketed for humans since the 1950s as Coumadin. It remains (along with the lung-and intestine-derived compound heparin) a popular blood thinner for millions of patients prone to strokes or blood clots.
Vampire bats treated with warfarin are subject to no such medical benefits. After capturing the bats in mist nets, the animals are painted with a mixture of warfarin and Vaseline and then released so that they can fly back to their roosts. Since vampire bats spend a considerable amount of time grooming one another, the toxic paste is soon spread throughout the members of the roost—with deadly results. Bats soon perish as the ingested warfarin induces massive internal hemorrhaging, causing them to bleed to death.
Although some might consider vampire bats dying from a clot-busting anticoagulant to be poetic justice, others might consider it to be a cruel waste of neat bats. In any event, warfarin paste is certainly several steps up from the days when cries for vampire bat heads sent folks scurrying for dynamite, poison gas, and flamethrowers. As long as vampire bat control personnel are applying the paste to the correct bats, this eradication method is relatively species specific. The drawback is that it’s successful only in places (like Trinidad) where individuals are trained to capture the right bat species, untangle them from mist nets (no easy task), and then apply the poisonous paste. All of this must be accomplished without injuring the bat, getting hammered by its powerful jaws, or painting a nonvampire