The Little Brown Bat (Myotis lucifugus) is one of the most common bat species found across North America. This small mammal plays a beneficial role in the ecosystem as an insectivore, consuming a high volume of insects nightly, including agricultural pests. While these bats are not inherently aggressive, their close association with human dwellings, such as attics and barns, introduces potential health risks. These risks primarily involve disease transmission and environmental hazards posed by their accumulated droppings.
Rabies Risk The Primary Concern
The most significant health concern associated with Little Brown Bats is the transmission of the rabies virus, a neurological disease that is nearly always fatal if left untreated. Although the incidence of rabies in bat populations remains low—less than one percent—bats are responsible for the majority of human rabies deaths in the United States. This occurs because bat bites can be incredibly small and may go unnoticed, especially if a person is asleep or a young child is involved.
Exposure occurs when the virus, present in the saliva of an infected bat, enters the body through a bite, scratch, or contact with mucous membranes. A bat found on the ground, struggling to fly, or active during daylight hours is exhibiting abnormal behavior, which indicates potential rabies infection. Since the incubation period for rabies can range from a few weeks to several months, seeking immediate medical attention following any potential contact is necessary.
If contact is suspected, immediately wash the wound thoroughly with soap and water. Post-exposure prophylaxis (PEP) must be administered by a healthcare professional, involving a series of rabies vaccinations and a dose of rabies immune globulin. This treatment is highly effective when given promptly. The bat involved should be safely contained, if possible, and submitted for testing, as a negative result can prevent the need for PEP.
Guano Hazards and Respiratory Health
The presence of bat droppings, known as guano, introduces a respiratory health hazard separate from rabies risk. Guano, especially when accumulated in large deposits within enclosed spaces like attics, can foster the growth of the fungus Histoplasma capsulatum. This fungus causes histoplasmosis, a lung infection.
The danger arises when dried guano is disturbed, such as during cleaning or construction, causing the microscopic fungal spores to become airborne and inhaled. Many people exposed to the spores experience no symptoms or only mild, flu-like illness. However, the infection can become serious, particularly for individuals with compromised immune systems, and in severe cases, it can spread beyond the lungs.
Scattered, fresh droppings pose a low risk, but large, older accumulations create an environment where the fungus thrives. If a bat colony is roosting in a structure, cleanup should not be undertaken by an untrained person. Professional remediation teams use specialized equipment, including HEPA filter vacuums and N-95 respirators, to safely remove the contaminated material and mitigate the spread of spores.
Safe Practices When Encountering Bats
The most effective way to avoid health risks is to prevent any physical interaction with Little Brown Bats. Never attempt to touch a bat with bare hands, regardless of whether it appears healthy or sick, alive or dead. Bats that are resting or flying normally should be left alone, as they pose no threat unless handled.
If a bat is found inside the living area of a home, especially in a room where people were sleeping, it must be contained for rabies testing. The Centers for Disease Control and Prevention recommends closing the doors and windows to the room. Once the bat lands, place a container, such as a coffee can or box, over it. A piece of cardboard can then be slid underneath to safely trap the animal without direct contact.
Local animal control or public health authorities should be contacted immediately to arrange for the bat’s collection and testing. If the bat is confirmed to have bitten or scratched a person or pet, or if contact is suspected, medical advice must be sought immediately. Containment for testing is the safest protocol, even for bats found in basements or garages.
Preventing bats from entering structures is the long-term solution to managing risk. Bats can fit through openings as narrow as a quarter of an inch. Inspecting the exterior of a home for small cracks, unsealed utility openings, loose screens, or gaps in the roofline and sealing them is necessary for bat-proofing. Exclusion work should be performed in the late summer or fall, after the young bats are able to fly, to avoid trapping them inside.