Vampiric Diseases: Rabies
It is now believed that rabies is the source of many vampire scares that occurred in the late 1700's, a Spanish neurologist, Dr Juan Gomez-Alonso, has formed a thesis based on historical documentations of rabies epidemics and of early tales of vampirism.
Tales of vampires frequently coincided with reports of rabies outbreaks in the Balkans, stretching back to an epidemic of rabies in dogs and wolves in Hungary from 1721-28.
Rabies is a virus that can affect the nervous system of any kind of mammal, this includes human beings as well. People are exposed to rabies when bitten by an infected animal, the disease can also be contracted through the brain matter of an infect animal. Rabies causes excessive production of saliva and foaming at the mouth, it can cause seizures and hallucinations. People infected with rabies react to stimuli such as water, light, odors and mirrors with spasms of the facial and vocal muscles that can cause hoarse sounds, bared teeth and the frothing of body fluid as well as saliva.
Rabies also causes wild fluctuations in pulse temperature and blood pressure of an effected individual. Although rabies is curable, it must be caught before symptoms appears. Symptoms can take anywhere from 4 days to years to appear.
Medical information taken from WebMd.