Bats play significant roles in ecosystems, controlling insects and pollinating plants. While generally not dangerous, bats can carry pathogens transmissible to humans. Understanding these potential health risks and how to mitigate them is important for public health.
Health Risks Posed by Bats
Bats are known reservoirs for several human diseases, with rabies being the most concerning. Rabies is a viral disease that attacks the central nervous system and is almost always fatal once symptoms appear. Initial symptoms resemble the flu, including headache and fever, before progressing to neurological signs like paralysis and delirium. In regions where domestic animal rabies is controlled by vaccination, bats are often the primary source of human cases.
Histoplasmosis is another health risk, a respiratory infection caused by inhaling microscopic fungal spores from the fungus Histoplasma capsulatum. This fungus thrives in soil enriched by large accumulations of bat guano. Symptoms range from mild, flu-like illness with fever, cough, and chest pain, to more severe or chronic lung conditions. Individuals with weakened immune systems are particularly susceptible.
Bats can also carry other lyssaviruses, closely related to rabies, which cause similar fatal illnesses affecting the central nervous system. An example is the Australian Bat Lyssavirus (ABLV). While human cases of ABLV infection are rare, they are almost always fatal.
How Diseases Spread from Bats
Rabies and other lyssaviruses primarily spread from bats to humans through direct contact, such as bites or scratches. The virus, present in the bat’s saliva, can also enter the body through mucous membranes (eyes, nose, or mouth) or broken skin. Bat teeth are very small, so a bite mark might be difficult to see or go unnoticed, especially if it occurs during sleep.
Histoplasmosis is not spread through direct contact with bats but by inhaling fungal spores. These spores become airborne when dried bat guano is disturbed, such as during attic cleaning or demolishing old structures. Casual proximity to bats or their roosts without direct physical interaction typically does not pose a significant risk for viral transmission.
Responding to Bat Encounters
If direct contact with a bat is suspected, thoroughly wash any wound (bite or scratch) with soap and water for several minutes. Seek prompt medical attention to assess the need for rabies post-exposure prophylaxis (PEP). Medical consultation is recommended even if a bite or scratch is not apparent, particularly if a bat is found in a room with a sleeping person, an unattended child, or an incapacitated individual, as tiny bat bites may go unnoticed.
If safe, capture the bat for rabies testing without direct handling, ensuring its head is undamaged for analysis. Contact local animal control or health authorities to facilitate capture and testing. Testing the bat can determine if rabies exposure occurred, potentially avoiding unnecessary medical treatments. If no direct contact is suspected and the bat appears healthy, it can be encouraged to leave by opening windows or doors.
Protecting Yourself from Bat-Related Illnesses
Preventing direct contact with bats is a primary method of protection. Never attempt to handle bats with bare hands, especially those that appear sick, injured, or are found on the ground. Educate children not to touch bats. If a bat is found indoors, contact local animal control or wildlife professionals for safe removal.
Bat-proofing homes is another effective strategy to minimize potential exposure. Bats can enter structures through small openings (1/4 to 3/4 inch). Inspect and seal gaps in rooflines, around vents, utility lines, and chimneys with materials like caulk, wire mesh, or steel wool. If bats are already roosting inside a home, professional wildlife removal services are recommended for humane exclusion using one-way devices. Additionally, ensure all household pets (dogs, cats, ferrets) are up-to-date on rabies vaccinations to help prevent transmission.