Researchers at the U.S. Centers for Disease Control and Prevention, in collaboration with the Peruvian Ministry of Health, conducted a survey in two communities in a remote section of the Peruvian Amazon where outbreaks of human rabies infections caused by vampire bats occurred regularly during the past two decades.
The study consisted of 92 people, 50 of whom reported previous bat bites. Blood samples were taken from 63 people, and 11 percent were found to have rabies virus neutralizing antibodies -- evidence they had been previously exposed to the rabies virus.
Although one person with antibodies reported receiving vaccine previously, the other people with antibodies are unlikely to have received medical care following prior bat bites. It could not be determined when the virus exposures occurred or which animals were responsible, but the history of repeated bat bites reported among persons in the area strongly suggests vampire bats as the source of rabies virus exposure.
"Nearly all rabies virus exposures that proceed to clinical infections are fatal. Our results support the idea that under very unique circumstances there may be some type of enhanced immune response in certain populations regularly exposed to the virus," Amy Gilbert of CDC's National Center for Emerging and Zoonotic Infectious Diseases, said in a statement. "However, a series of injections following an exposure remains the best way to protect people against rabies."