The rabies virus is well established as being as close to 100% fatal as any disease in humans or mammals with very few documented survivors. You could count the number of survivors on one hand, until now.
However, according to a study published last week in the American Journal of Tropical Medicine and Hygiene, researchers from the Centers for Disease Control and Prevention (CDC) and Ministerio de Salud in Lima, Peru demonstrates that some Peruvian Amazons have survived the usually fatal virus without vaccination.
In the study, CDC researchers found that approximately 10% of those tested from a couple of remote villages in Peru had built up an immune response and survived the usually lethal infection.
The study consisted of 92 people, 50 of whom reported previous bat bites. Blood samples were taken from 63 people, and 7 (11%) were found to have “rabies virus neutralizing antibodies,” evidence that 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 this area strongly suggests vampire bats as the source of rabies virus exposure.
According to Amy Gilbert, PhD, of CDC’s National Center for Emerging and Zoonotic Infectious Diseases and lead author of the study, “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, which could prevent onset of clinical illness. However, a series of injections following an exposure remains the best way to protect people against rabies.”
Outbreaks of rabies in these remote villages are seen on a regular basis due to exposure to vampire bats.
According to the CDC, More than 55,000 people die of rabies each year. The rabies virus infects the central nervous system, ultimately causing disease in the brain and death. The early symptoms of rabies include fever, headache, and general weakness or discomfort. As the disease progresses, more specific symptoms appear and may include insomnia, anxiety, confusion, slight or partial paralysis, excitation, hallucinations, agitation, hypersalivation (increase in saliva), difficulty swallowing, and hydrophobia (fear of water). Death usually occurs within days of the onset of these symptoms.