A South American species of a hairy-legged vampire bat has been found feeding on human blood for the first time, sparking concerns about the transmission of diseases.

Brazilian scientists analyzed the feces of the bats and found traces of DNA from human blood in three of the excrement samples of the vampire bat.

According to the study published in the journal Acta Chiropterologica, the bat species, which lives in the Caatinga dry forests of north-east Brazil, is usually a fastidious eater and only feeds on birds' blood. However, scientists say that the bats are adapting fast and are apparently consuming human blood regularly.

It has been suggested that human activity might be the cause of the bats' changing tastes. According to the authors of the study, the record of humans as prey and the absence of blood from native species is a possible reflection of a low availability of wild birds in the study site, reinforcing the impact of human activities on local ecological processes.

Humans are increasingly inhabiting the forests and bringing domestic animals with them. Birds like guans and tinamous, which are the bats' favored source of blood, are being driven out of the area.

The study left the scientists surprised. The lead author of the study, Enrico Bernanrd of the Federal University of Pernambuco, said, this species is not adapted to feed on the blood of mammals.

Additionally, bats are known to transmit rabies in Brazil. In the year 2005, the disease killed 23 people in northern Brazil within two months, and a total of 55 cases of rabies in humans have been reported in the Amazon region.