What constitutes an exposure?
The vast majority of human rabies cases in the USA have resulted from virus types that are carried by bats. Significantly, most of these case-patients did not report having been bitten by a bat. This suggests that some bites or scratches from bats may be so minor as to go unnoticed, disregarded, or forgotten, yet can still result in transmission of the rabies virus. Accordingly, criteria for considering whether a person has sustained a potential rabies exposure are different when bats are involved.
Clearly, a bite, scratch, or mucous membrane contact with a bat should be considered a potential rabies exposure. However, postexposure prophylaxis should also be considered whenever direct contact between a human and a bat has occurred, unless the person can explicitly rule out the possibility of a bite, scratch, or mucosal exposure.
Furthermore, prophylaxis can be considered for persons who were in the same room as a bat, but who might be unaware that a bite or direct contact had occurred (e.g., a sleeping person awakens to find a bat in the room, or an adult witnesses a bat in the room with a previously unattended child, mentally disabled person, or intoxicated person).
In all instances of potential bat exposures, the bat in question should be safely collected, if possible, and submitted for rabies diagnosis. This will eliminate the need to consider prophylaxis in most cases.
It is important to note that these recommendations regarding postexposure prophylaxis for bat contact exist because of the possibility that a bite or scratch from a bat may go unnoticed due to the patient's age or level of consciousness. They should NOT be construed to mean that simply being in the same area as a bat constitutes an exposure for a competent conscious adult or older child.