Bats and RabiesWhat is "Significant" Contact?
ABSTRACT & COMMENTARY
Synopsis: Two cases of death from rabies were shown by DNA studies to be bat-associated, but the subjects had no history of close exposure to bats.
Source: Centers for Disease Control and Prevention. Human rabiesMontana and Washington, 1997. MMWR Morb Mortal Wkly Rep 1997;46:770-774.
Two recent cases of encephalitis initially diagnosed as Creutzfeldt-Jakob disease were diagnosed as rabies by histologic examination on autopsy. DNA sequencing indicated that bats were the sources of exposure. The family of one man reported a bat that had entered their home for several days, roosting during the daytime and flying around the house at night. The bat had no known direct contact with the patient. A second man lived in a rural area where bats were common but had no known direct contact with bats.
n COMMENT BY HAL B. JENSON, MD, FAAP
Bat rabies is enzootic in the contiguous United States, and close contact with bats is extremely high-risk for transmission of rabies. Of the 19 cases of bat-related cases of human rabies since 1980, one case had a history of animal bite, eight cases reported only physical contact, and 10 cases had no known direct contact. A dilemma is often faced in the management of a child or adult with a history of exposure but not direct contact to batshow much contact with bats is "significant" and necessitates postexposure prophylaxis for rabies? These cases emphasize that seemingly insignificant physical contact with bats may result in rabies transmission, even without a documented history of a bite or direct contact.
In all instances of human contact with bats in which rabies transmission is being considered, the bat should be collected, when feasible, and submitted for rabies testing. Postexposure rabies prophylaxis is indicated for all persons with a history of a bat bite, scratch, or mucous membrane exposure unless the bat is available for testing and is negative for evidence of rabies. Furthermore, postexposure prophylaxis is appropriate after exposure, even in the absence of known direct contact, in situations in which there is a reasonable probability that such contact occurred (i.e., a sleeping person who awakens to find a bat in the room, an adult who witnesses a bat in the room with a previously unattended child, a mentally disabled person, or an intoxicated person). Rabies is rare in the United States but should be considered in the differential diagnosis of persons with unexplained rapidly progressing encephalitis.
True statements about human rabies include all of the following except:
a. rabies prophylaxis is indicated for a bat bite when the bat is found not to have histological evidence of rabies.
b. rabies prophylaxis is indicated after a bat bite when the bat cannot be recovered.
c. rabies can be transmitted from bats even when the history of a bite or scratch is not present.
d. the probable source of exposure can sometimes be identified by DNA analysis.
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