Bats

Bats are mammals in the order Chiropter. The forelimbs of all bats are developed as wings, making them the only mammals naturally capable of sustained flight (other mammals, such as flying squirrels, gliding possums and colugos, can only glide for limited distances). The word Chiroptera comes from the Greek words cheir “hand” and pteron “wing,” as the structure of the open wing is very similar to an outspread human hand with a membrane (patagium) between the fingers that also stretches between hand and body. Bats range in size from Kitti’s Hog-nosed Bat measuring 29-33 mm (1.14 – 1.30 in) in length and 2 g (0.07 oz) in mass, to the Giant golden-crowned flying fox which has a wing span of 1.5 m (4 ft 11 in) and weighs approximately 1.2 kg (3 lb).

Bats as Vectors for Pathogens

Bats are natural reservoirs or vectors for a large number of zoonotic pathogens including rabies, severe acute respiratory syndrome (SARS), Henipavirus (ie. Nipah virus and Hendra virus) and possibly ebola virus. Their high mobility, broad distribution, and social behaviour (communal roosting, fission-fusion social structure) make bats favorable hosts and vectors of disease. Many species also appear to have a high tolerance for harboring pathogens and often do not develop disease while infected.

Only 0.5% of bats carry rabies. However, of the few cases of rabies reported in the United States every year, most are caused by bat bites. Although most bats do not have rabies, those that do may be clumsy, disoriented, and unable to fly, which makes it more likely that they will come into contact with humans. Although one should not have an unreasonable fear of bats, one should avoid handling them or having them in one’s living space, as with any wild animal. If a bat is found in living quarters near a child, mentally handicapped person, intoxicated person, sleeping person, or pet, the person or pet should receive immediate medical attention for rabies. Bats have very small teeth and can bite a sleeping person without being felt. There is evidence that it is possible for the bat rabies virus to infect victims purely through airborne transmission, without direct physical contact of the victim with the bat itself.

If a bat is found in a house and the possibility of exposure cannot be ruled out, the bat should be sequestered and an animal control officer called immediately, so that the bat can be analyzed. This also applies if the bat is found dead. If it is certain that nobody has been exposed to the bat, it should be removed from the house.