Bats play a crucial ecological role in pest control and pollination. They are the only mammals capable of sustained flight, consuming vast numbers of insects. While often feared, the actual dangers bats pose are specific, manageable, and largely related to disease transmission. Safe coexistence requires understanding these specific health concerns without unwarranted anxiety.
The Primary Health Threat: Rabies
Rabies is a severe viral disease that affects the central nervous system and is nearly 100% fatal once clinical symptoms begin. Bats are the most frequent cause of human rabies deaths in the United States, accounting for approximately 70% of cases acquired domestically. This is because bat bites can be tiny and go unnoticed, leading to a failure to seek treatment. Transmission occurs when saliva from an infected bat enters the body, typically through a bite or scratch.
Bat teeth are extremely small, meaning a bite may feel like a small pinprick or go completely undetected, especially if the victim is sleeping or a child. Rabies is almost entirely preventable through prompt medical care called Post-Exposure Prophylaxis (PEP). Seeking PEP involves receiving rabies immune globulin and a series of vaccines, which must be administered before symptoms manifest. Less than 1% of the wild bat population carries the virus, but any direct contact must be taken seriously, as sick bats are often encountered by people.
Secondary Health Risks from Bat Colonies
Established bat colonies pose health concerns related to their accumulated waste. Bat feces, known as guano, provides an ideal environment for the growth of the fungus Histoplasma capsulatum. This fungus is the source of Histoplasmosis, a respiratory infection that affects the lungs.
The risk of infection comes from inhaling microscopic fungal spores that become airborne when large, dried deposits of guano are disturbed. This is a concern in confined spaces like attics or chimneys where colonies have been present for a long time. Symptoms are often flu-like, and while many people recover, the disease can become severe for those with weakened immune systems.
Cleanup of significant guano accumulation should always be performed by professionals wearing specialized protective gear, including HEPA filter masks. Disturbing the material through sweeping or vacuuming without proper containment can release a cloud of spores, increasing the risk of exposure. Homeowners should avoid attempting to remove large guano piles themselves to mitigate the inhalation hazard.
Immediate Action: Handling Bat Encounters Safely
If a bat is found inside a living space, the first priority is to prevent direct contact and assess the risk of exposure. If the bat is in a room with a sleeping person, an unattended child, or someone with impaired judgment, assume an unnoticed bite or scratch may have occurred. In these situations, the bat must be safely contained for rabies testing, and medical attention should be sought immediately.
To safely capture a bat for testing, first put on thick leather work gloves. Do not harm the bat, as its brain must remain intact for laboratory testing.
- Wait for the bat to land on a surface, then slowly place a small container over it.
- Slide a piece of stiff cardboard underneath the container to trap the bat inside.
- Secure the lid with tape.
- Poke small breathing holes.
Once the bat is secured, contact your local public health department or animal control for instructions on submitting the specimen. If the bat cannot be captured or if testing results are inconclusive, medical professionals will likely recommend Post-Exposure Prophylaxis. To prevent future encounters, homeowners should inspect their house and seal any openings larger than a quarter-inch by a half-inch.
Dispelling Common Misconceptions
Many fears about bats stem from long-standing myths that misrepresent their behavior. The phrase “blind as a bat” is inaccurate, as all bats have functional eyes and can see well, especially in low light conditions. While they primarily use echolocation—a biological sonar—to navigate and find insects, their vision aids in long-distance travel.
Bats do not actively seek to attack humans or intentionally get tangled in hair. They are insectivores that frequently fly near people because human body heat and exhaled carbon dioxide can attract insects, their intended target. Their erratic flight patterns result from hunting airborne prey, and they are motivated to avoid contact with people.
The idea that all bats carry disease is a misconception; only a very small percentage of the population is infected with rabies. Bats are not flying rodents, but belong to their own distinct biological order, Chiroptera, and are more closely related to primates than to mice.