Post-exposure prophylaxis is indicated when someone has been in a room with a bat, even if direct contact with the animal is uncertain. Examples of this would include “a sleeping person [who] 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.”7 Following a bite requiring post-exposure prophylaxis treatment, it is pertinent to note if the patient has had a previous immunization. Regardless of immunization status, all bite areas must be thoroughly cleansed and irrigated. The CDC recommends using a virucidal agent, such as a povidine-iodine solution, in the cleansing process. If an individual has been previously immunized to rabies, then the rabies immunoglobulin (RIG) should not be administered; rather, the patient should be given the rabies vaccine, such as the human diploid cell culture rabies vaccine (HDCV) or the purified chick embryo cell vaccine (PCECV). The dose is 1 mL intramuscularly on day 0 and day 3. If a patient has not had either pre-exposure or prior post-exposure vaccinations, then RIG is also indicated. The full dose of RIG should be given at the site of the bite; however, if this is not feasible due to the location of the wound, then any remainder should be given at a site distant from the vaccine. The rabies vaccine (HDCV or PCECV) should be administered intramuscularly on days 0, 3, 7, and 14. A fifth dose may be considered on day 28 for immunocompromised patients. In adults, the vaccine should be given in the deltoid region, whereas in children it can also be given in the anterolateral aspect of the thigh. It should never be administered in the gluteal region because it may result in lower antibody titers.8 It is extremely important to administer the RIG in unvaccinated persons. A case report was reviewed from India in which a 45-year-old woman presented with fever, headache, dizziness, and hearing loss 1 month after being bitten by a mongoose on her right leg. She was given 4 doses of a rabies vaccine on days 0, 3, 7, and 28 but was not given RIG. Rabies virus neutralizing antibody titers in the cerebral spinal fluid were initially 2,048 IU/mL and increased after 2 weeks to greater than 16,384 IU/mL confirming the diagnosis of rabies encephalitis. The patient died 1 month after admission.9 The incubation period for rabies is 1 to 3 months in general, but a range from days to years has been reported.6 Post-exposure prophylaxis should typically be initiated as soon as possible after a bite; however, it may be delayed up to 10 days after exposure if the animal has been captured and can be monitored for signs of rabies or euthanized and tested. It is recommended that anyone who presents for evaluation after possible exposure, regardless of timeline, should be treated as if the contact had just occurred.10
Case Conclusion
In this case of the chipmunk bite, in accordance with the state health department, rabies prophylaxis was not indicated. It was recommended that the chipmunk be sent off for a necropsy (noting to leave the chipmunk intact and not to behead it). Following shared decision making with the patient and her husband, the chipmunk was sent off for testing with the results to be sent to the patient. She was discharged from the ED with Augmentin, but without rabies post-exposure prophylaxis. According to review of outpatient medical records, the patient was doing well at primary care appointments after the injury.