Postcard From...Lima

Are they superhumans? Or just genetically blessed? American scientists studying remote communities in the Peruvian Amazon ravaged by vampire bats have found the first evidence of humans immune to rabies.

The team from the US government's Centres for Disease Control and Prevention (CDC) found that six of 63 people tested had rabies anti-bodies in their blood, without ever having been vaccinated for the disease. The 63 were part of a larger sample group of 92, 50 of whom reported having been bitten by bats.

It remains unclear whether the six were born with the anti-bodies or developed them after being infected with rabies and surviving despite the lack of medical facilities in villages rarely visited by doctors.

Either way, the discovery, revealed in this month's American Journal of Tropical Medicine and Hygiene, turns on its head the traditional notion that without immediate treatment, exposure to rabies means a certain hideous death.

Amy Gilbert, the lead researcher, said that death was still the nearly inevitable fate for anyone developing rabies symptoms, even with the best medical care. However, the new research indicates that some people exposed to the disease may never develop those symptoms.

"These are very small villages and, when they witness 10 people dying from what is a horrible disease, it is incredibly traumatic," said Ms Gilbert. "We want to help raise awareness of the problem and try to develop a more proactive response."

The CDC discovery is now expected to pave the way for pioneering research to develop both new kinds of vaccinations and treatment for rabies. That could even involve genome sequencing.