The Hidden Danger that Bats Leave Behind: Guano

With winter coming on, many types of animals look for refuges from the cold. Many times this means human habitats that they intend to stay in through the winter. Along with the mice and bugs, many homes will become a refuge for bats. The conventional wisdom to avoid a wild bat is true- they are susceptible to rabies and can spread it even through a very tiny bite. But after they are gone, the danger remains in your home- but not from rabies.

Bat guano can build up in attics and eaves that have been used by bats, and even if the human occupants of the building are not aware of the dung, they can be harmed by it. After guano has lain around for a couple of years, a fungus can grow in it, releasing spores into the air that cause histoplasmosis in humans. The east and central parts of the U.S. are especially susceptible to the fungus that causes this disease.

Histoplasmosis can cause serious respiratory diseases in humans, causing fever and chest pains. If left untreated, histoplsmosis can turn into a chronic lung disease that resembles tuburculosis. In the very young and the very old, or people who already have cancer, AIDS or other serious illnesses, histoplasmosis can be fatal. Histoplasmosis can also travel from the lungs to the eyes, causing ocular histoplasmosis syndrome, which destroys the central vision (not periphreal). The lung problems can many times be cured with anti-fungal medications, but the ocular disease has no cure.

If bat guano is found in a home or other building, it is important to have it removed as soon as possible by a trained professional. A professional will search for any roosting bats that may be inside, then for any passageways that may be accessible to bats. Any points of entry have to be closed so that the bats do not reappear.

To remove guano, a professional will wear a respirator and dress in protective gear. The guano is usually sprayed with water or a fungicide so that the removal process will not cause the fungus to become airborne. It can then be cleaned up via a specialized vacuum, together with cleaning chemicals, or can be collected manually, or a combination of both.

If bat guano has been found in the house, especially if it has been there for a few years, it is important to watch for any symptoms and to get medical attention if any lung or eye disease symptoms begin. Early treatment is extremely important in the ocular histoplasmosis, as laser treatments can stop the vision loss, though they can not restore any vision that has already been lost.