Bats are among the most unique and fascinating of all animals. No other mammals can fly. Bats use echolocation to find flying insects at night much like sonar helps ships locate objects under water. Bats also have good night vision. They are not blind, as myth would have it.
While Midwestern bats feed exclusively on insects, consuming many pest species, they prefer to expend the least amount of energy to obtain the most food. Thus bats typically capture larger insects, such as night-flying moths, and do not live up to their reputation for controlling mosquitoes.
Correctly considered beneficial animals, in certain situations bats, however, pose a threat to human health. Histoplasmosis is a disease associated with bat guano and bird droppings. When droppings accumulate for years, a fungus (Histoplasma capsulatum) can grow and produce spores that may cause histoplasmosis when inhaled. Where bat or bird droppings accumulate, in an attic for example, care should be taken to avoid contracting this disease. Clean up generally involves wetting the droppings before removal and wearing personal protective equipment, including a HEPA-equipped respirator or self-contained breathing apparatus (SCBA). Removal of large amounts of guano or droppings from structures should be left to experienced professionals familiar with proper removal procedures. For more information on histoplasmosis and clean-up procedures see the following Web sites:
Perhaps the greatest health risk from bats is rabies. In Florida, rabies is found in bats more than any other wildlife species. Yet it should be noted that typically less than 5 percent of bats tested for rabies are found to be rabid. In the bat population as a whole, the percentage of rabid bats is much smaller – less than 1 percent.
Rabies is a viral disease causing encephalitis (brain inflammation) in humans and animals. Humans can become infected when bitten by a rabid bat. Transmission also can occur when an infected bat’s saliva (but not blood, urine or feces unless these are mixed with spinal fluid – as can happen when a bat is beaten or crushed) comes in contact with a person’s eye, nose, mouth, a scratch or wound. Contact with aerosolized bat saliva, especially where large numbers of bats are roosting, also can transmit rabies to humans, although this type of transmission is quite rare. For further information on rabies, contact your local health department.
Of less importance are parasites associated with bats. Fleas, lice, mites and bat bugs can infest bats, birds and other animals. Some may transmit diseases to humans. If the host animals are killed or leave their nests or roosts, the parasites look for alternate hosts and may wander into the living spaces of structures. They may bite people and domestic animals, but most parasites cannot live long away from their preferred hosts. Control can often be accomplished by simply vacuuming the parasites and carefully discarding the vacuumed material. Sometimes, bat parasites such as bat bugs may have to be eliminated by application of pesticides labeled for this purpose.