Vampire bats who have been driven out of their homes in the Amazon have been spreading disease across north Brazil.
The bats, whose habitats have been destroyed by deforestation, are carrying rabies. They have bitten lots of people and some of them have died.
More than 1,300 people have now been given anti-rabies medicine to stop them getting the disease.
The bats are also being sprayed with poison in an effort to kill off the infected creatures.
Vampire bats are found across South America. They feed on the blood of creatures including birds, horses and cattle.
They have been flying into people's homes and biting them while they are sleeping.
Many people are now blocking up openings in their homes to try to keep the bats out.