Animal bites and suspected human rabies exposures
Animal bites are a public health concern because of the potential for transmission of rabies, a viral infection of the nervous system and brain of humans and other mammals that is practically always fatal. A suspected human rabies exposure occurs when saliva or other possibly infectious material (such as central nervous system tissue) from a potentially infected animal penetrates the skin or comes into contact with mucosal surfaces. Rabies is not transmitted by contact with blood, urine, feces, or fur.
Bats are a special case because bat variant rabies has been documented in persons with no history of a scratch or a bite. Any potential human exposure to a bat requires careful assessment because bat teeth are razor sharp and tiny, so a bite wound may not be detectable on physical examination.
Although terrestrial carnivores such as raccoons, skunks, foxes and coyotes are known to harbor rabies in other parts of the country, bats are the only known reservoir for rabies in Washington state. Over the past several decades, only four non-bat animals have tested positive for rabies in Washington (one each of a cat, dog, llama and horse), two of which were infected with a bat-variant of rabies (the strain type was unknown for the other two animals).
If a person is exposed to rabies, infection can be prevented by administering rabies immune globulin and a series of rabies vaccine doses. To be effective, preventive treatment must be started before symptoms appear and must be given according to a specific schedule.
Resources for the general public
Resources for health care providers
Health advisory: July 10, 2009
Change in ACIP recommendation for rabies PEP vaccine series
Suspected rabies exposure in King County
Purpose of surveillance:
- To identify persons potentially exposed to rabies and to ensure appropriate evaluation and preventive treatment if necessary
- To ensure that potentially rabid animals are managed appropriately
- To identify animal sources of rabies and risk factors for rabies transmission
In 2012, a total of 68 suspected rabies exposures were reported. Forty-seven (69%) of the 68 suspected rabies exposure cases resulted from exposures to bats within King County or other areas of the United States. In all but one of these cases, a bat was not available for rabies testing; one bat tested positive for rabies. Fourteen (21%) exposures to animals including dogs and monkeys occurred outside the United States. An additional 236 non-reportable animal bite reports were received by Public Health.
Forty nine animals associated with potential human rabies exposures were tested for rabies. Of these, one bat was found to be positive for rabies. In Washington state, almost all cases of animal rabies occur in bats, however, most bats do not carry rabies. From 2000-2011, on average, 6% of the sick or injured bats tested were positive for rabies each year.
The last identified cases of rabies in humans in Washington occurred in 1995 and 1997, both attributed to bat exposures. Prior to that, the last identified human case of rabies occurred in 1939 from the bite of a rabid dog. In February of 2011, reporting requirements were changed so that only animal bites that are suspected rabies exposures are immediately notifiable.