Rabid vampire bats attack Brazilian children

Gaia Vince / New Scientist | November 4 2005

Brazilian children are being menaced while they sleep by rabid vampire bats that have killed 23 people and bitten more than 1300 since September.

The winged creatures enter people’s homes at night and suck blood from the youngsters’ face or fingers. The Brazilian authorities attribute the large proportion of children attacked – 18 of the 23 killed were minors – to the fact that youngsters sleep more soundly than adults and are less likely to be disturbed by the bats.

“A vampire bat bite does not leave a gaping wound – it’s more like a small graze. Many people don’t even realise they’ve been bitten,” says Tony Fooks, head of the Rabies and Wildlife Zoonoses Group at the UK’s Veterinary Laboratory Agency in Weybridge, Surrey.

Untreated, rabies is almost always fatal – the virus attacks the central nervous system causing severe pain, confusion and a highly disturbed mental state which includes phobias, often including hydrophobia, the fear of water. However, if an anti-rabies vaccine is administered within 24 hours of the bite, the survival rate is high.

Plugging the gaps
The attacks have all taken place at night time in the northern Brazilian state of Maranhao. The state health authority does not know how many of those bitten may have been infected with rabies, but has treated 1350 people with anti-rabies vaccines so far. They have also been spraying bats from infected colonies with poison in the hope that they fly back to their roosts and kill off others.

“Vampire bats are usually shy of humans, but rabies makes them lose their shyness and seek humans for a blood meal,” Fooks told New Scientist.

Many homes in the marshland area have gaps in the floor and ceiling and no screens on the windows. Residents have been advised to stay in at night, to sleep under mosquito nets and to cover gaps in their houses with banana leaves or cloth, the Maranhao newspaper O Imparcial reports.

“Just like with malaria, sleeping under mosquito nets is a very successful preventative, but the poorest people, who have the houses which offer the worst protection, cannot afford nets,” says Sarah Cleaveland, a rabies expert at the Centre for Tropical Veterinary Medicine at the University of Edinburgh, UK.

Cattle feed
Rabies outbreaks have occurred every year in Brazil since 1986, but the authorities say that this year's is particularly severe. Blood-seeking vampire bats continually prey on cattle and horses in the region. The debilitating effect of the bites and the diseases the bats spread are a major economic burden.

The increasing rabies problem is being blamed on two connected factors. Deforestation of the Amazon is forcing thousands of bats from their natural habitat and into close contact with humans. Furthermore, trees are often cleared to provide a home for cattle, which provides a rich food source for the bats, leading to much larger colonies.

Authorities in the area have worked hard over the past few years to control the rabies problem in dogs, but bat infestations are proving more difficult. The only solution at the moment is preventing bites. Attempted mass culls have been unsuccessful since the bats inhabit hidden pockets in hard-to-reach caves.

Researchers are working towards rabies vaccination treatments for bats which they hope could provide an alternative solution.