Saliva from some bats, particularly vampire bats, contains an enzyme that keeps blood from coagulating, or clotting. The main potential use for this saliva is as a medicine to break up blood clots in stroke patients. Injecting bat saliva into stroke patients may be as effective as the more commonly used stroke treatment, alteplase. Some studies have also shown that bat saliva may also work up to nine hours after a person has had a stroke, whereas alteplase can usually only be used up to about four hours afterward.
Known scientifically as Desmodus rotundus, the common vampire bat is a type of bat that feeds on the blood of other animals. Unlike mythical vampires, vampire bats do not suck blood; instead, they lick it up with their long tongues. To keep the blood flowing from the wound, a vampire bat will deposit some saliva into the wound.
Vampire bat saliva has an unusual enzyme that has very strong ant-clotting properties and also prevents nearby blood vessels from closing. Ischemic strokes happen when blood flow in the brain is blocked due to a blood clot, so researchers are studying whether this enzyme could help break up such clots. As of 2011, this stroke treatment was still being investigated, but scientists were hopeful that bat saliva could be used as a treatment for strokes by 2015.
Scientists have found that injecting a medication made from bat saliva directly into a stroke sufferer's bloodstream can help break up blood clots. This solution has been dubbed desmoteplase, after the scientific name of the common vampire bat. Some scientists believe that it may actually be more effective than the traditional medicine used to break up blood clots.
Using current stroke treatment methods, medical professionals generally have a little over four hours to inject alteplase into a patient's veins. After this time, this medication is usually not able to break up blood clots that cause ischemic strokes. The bat saliva medication, on the other hand, may still be effective even when injected into a stroke victim several hours later.
Alteplase also can cause very heavy bleeding in some patients, which can be very dangerous. Desmoteplase, on the other hand, seems to cause little or no side effects in most people. Studies currently suggest that it may be safer than alteplase.