A 22-year-old woman comes to the emergency department for evaluation of a bite on her right arm by her neighbors' dog. The neighbors accompany the patient with their dog, which is not immunized against rabies but appears healthy. The patient has no other medical conditions and takes no medications. Her last tetanus booster was 3 years ago. Temperature is 37 C (98.6 F), blood pressure is 110/70 mm Hg, pulse is 76/min, and respirations are 12/min. On her right forearm is a shallow bite wound that is 1 cm long with no erythema or purulent drainage. The wound is cleaned with soap, water, and povidone-iodine solution, and antibiotic prophylaxis is initiated. Which of the following is the best next step in management of this patient?
Show Explanatory Sources
Rabies is a fatal disease transmitted by a bite from an infected mammal. In developing countries, dogs account for >90% of transmissions due to inadequate rabies control programs. In contrast, rabies is rare in dogs in the United States due to widespread vaccination. Most rabies cases in the United States are due to bites from wild animals (eg, bats, raccoons).
For patients who have not previously received rabies vaccination, postexposure prophylaxis (PEP) consists of rabies immunoglobulin plus a series of rabies immunizations. However, the decision to administer PEP is guided by a variety of factors, as follows:
Patients bitten by high-risk wild animals (eg, bats, raccoons, foxes, skunks) should receive PEP if the animal is unavailable for testing. Because bat bites can go unrecognized, PEP is also recommended following direct exposure to bats (unless the patient is certain a bite or scratch was not inflicted). In the rare situation that the high-risk wild animal is available for testing, PEP can be withheld until the animal is euthanized and its brain is tested for rabies.
Patients bitten by pets in the United States do not require PEP if the animal appears healthy and is available for quarantine (as in this case). Contagious animals (ie, rabies virus present in saliva) are symptomatic within 5-10 days; therefore, pets can be observed for 10 days for signs of rabies without administering PEP immediately (Choice D). However, if the pet is unavailable for quarantine or is symptomatic, PEP should be administered.
Patients bitten by low-risk animals (eg, squirrels, chipmunks) do not need PEP.
All wounds should also be thoroughly cleaned with a viricidal agent such as povidone-iodine.
(Choices A and B) An asymptomatic, healthy dog can be observed for 10 days for signs of rabies. There is no need to euthanize it for testing because there have been no rabies cases in the United States due to a cat or dog that has been observed for 10 days.
(Choice E) Patients with bites from high-risk wild animals or certain domestic animals (eg, dog, cat, ferret) should start PEP if the animal is unavailable. However, if the animal is available, either observation (pets) or testing (wild animals) should be performed before deciding on PEP.
Educational objective:
For patients who have not previously received the rabies vaccination, rabies postexposure prophylaxis (PEP) includes rabies vaccine and rabies immunoglobulin. PEP is indicated when a domestic (eg, dog, cat, ferret) or high-risk (eg, bat, racoon, fox, skunk) animal is unavailable for observation or testing. Available, asymptomatic animals can either be observed (pets, for 10 days) or tested (wild animals) to determine the need for PEP.