Ask all patients about bat and animal exposure when rabies is in the differential. Worldwide, there are 55,000 cases of human rabies a year. The vast majority of these occur in developing countries as a result of dog bites. In the United States, there is only a handful of human cases of rabies each year, almost always associated with bat exposure. It is not necessary to get a bat bite or scratch to be at risk for rabies. Some U.S. patients seem to have contracted rabies after exposure to bat saliva or vapors, sometimes having been bitten while asleep. Any patient who wakes up in a room or cabin and finds a bat should be considered at risk for rabies.
Other animals commonly infected with rabies in the U.S. include raccoons, skunks, and foxes. Unvaccinated dogs and cats also are at risk of rabies.
Consider prevention the best treatment. Wash bite wounds with 20% soap and irrigate with povidone-iodine to reduce the risk of rabies by up to 90%. If the biting animal is available for observation, the rabies vaccine may be deferred or not administered at all if the animal is well after 10 days. Many state laboratories will also perform rabies testing on euthanized animals. If the biting animal is unavailable for observation, promptly give the rabies vaccine and immune globulin. Current rabies vaccines are safe and highly effective in preventing infection after exposure, provided they are given in a timely fashion. Vaccine and immune globulin have no role in treatment once rabies symptoms have developed. TH
Dr. Ross is an associate physician and hospitalist at Brigham and Women’s Hospital, Boston, and a fellow of the Infectious Diseases Society of America. Contact him at [email protected].
References
- Willoughby RE Jr, Tieves KS, Hoffman GM, et al. Survival after treatment of rabies with induction of coma. N Engl J Med. 2005;352(24):2508-2514.
- Johnson M, Nelson K. Down to a prayer. Milwaukee Journal Sentinel. June 18, 2005.
- Nelson K. Potential cure for rabies fails in others. Milwaukee Journal Sentinel. April 22, 2007.
- Centers for Disease Control and Prevention. Human rabies Indiana and California, 2006. MMWR. 2007;56(15):361-365.