What are the criteria for administering rabies immunoglobulin (RIG) to individuals exposed to potentially rabid animals?

Rabies Immunoglobulin Administration Criteria

Rabies immunoglobulin (RIG) should be administered to all previously unvaccinated persons with documented or suspected rabies exposure from bite or nonbite exposures, regardless of the time interval since exposure, provided clinical signs of rabies are not present. 1

Primary Indication for RIG

RIG is indicated for previously unvaccinated individuals only. The essential criterion is lack of prior complete rabies vaccination with a cell culture vaccine or absence of documented rabies antibody titers. 1

Patients Who Should Receive RIG:

• Any person with no history of complete pre-exposure or post-exposure rabies vaccination who sustains a bite or nonbite exposure from a suspected or confirmed rabid animal 1, 2
• Bite exposures: Any penetration of skin by teeth from a potentially rabid animal, including minor injuries from bats that may be undetected 1, 3
• Nonbite exposures: Scratches, abrasions, open wounds, or mucous membranes contaminated with saliva or potentially infectious material (such as brain tissue) from a rabid animal 3

Patients Who Should NOT Receive RIG:

• Persons who have previously received complete pre-exposure or post-exposure vaccination regimens with cell culture vaccines (HDCV, RVA, or PCEC) 1
• Persons with documented rabies virus neutralizing antibody titers from prior vaccination 1, 2
• Previously vaccinated individuals should receive vaccine only (2 doses on days 0 and 3), as RIG will suppress the anamnestic antibody response 2

Timing Criteria

RIG must be administered as soon as possible after exposure, ideally on day 0 simultaneously with the first vaccine dose. 1, 2, 3

• If not given on day 0, RIG can still be administered up to and including day 7 after the first vaccine dose 1, 2
• Beyond day 7, RIG is contraindicated because an antibody response to cell culture vaccine is presumed to have occurred 1, 3
• There is no time limit from exposure to initiation of prophylaxis—even delays of months or years warrant treatment if clinical rabies signs are absent, as incubation periods exceeding 1 year have been documented 1, 2

Dosing and Administration Criteria

The dose is exactly 20 IU/kg body weight for all age groups, including children. 1, 2, 3

Critical Administration Requirements:

• The full calculated dose should be thoroughly infiltrated in and around all wounds if anatomically feasible 1, 2, 4
• Any remaining volume after wound infiltration should be injected intramuscularly at a site distant from vaccine administration 1, 2
• Never exceed the recommended 20 IU/kg dose, as higher doses can partially suppress active antibody production 1, 2
• Never administer RIG in the same syringe or same anatomical site as the first vaccine dose 1, 2
• RIG is administered only once during the entire prophylaxis course 1, 3

Animal-Specific Criteria

Dogs, Cats, and Ferrets:

• Healthy animals that bite can be confined and observed for 10 days 1, 3
• Do not initiate RIG during the observation period unless the animal develops signs of rabies or cannot be observed 1, 3
• If the animal remains healthy for 10 days, it was not shedding virus at the time of bite and RIG is not needed 1
• Stray or unwanted animals should either be observed for 10 days or euthanized immediately for testing; initiate RIG immediately if testing is pursued 1, 3

Wild Carnivores (Skunks, Bats, Foxes, Coyotes, Raccoons, Bobcats):

• Regard as rabid unless proven negative by laboratory testing 3
• Initiate RIG and vaccine immediately without waiting for test results 3

Livestock, Rodents, and Lagomorphs:

• Consult local public health officials 3
• Bites from squirrels, hamsters, guinea pigs, gerbils, chipmunks, rats, mice, rabbits, and hares almost never require RIG 3

Special Population Criteria

Immunocompromised patients require RIG at the standard 20 IU/kg dose plus a 5-dose vaccine regimen (days 0,3,7,14, and 28), even if previously vaccinated. 2

Pediatric patients receive the same weight-based dosing (20 IU/kg) as adults, with demonstrated safety and efficacy in children. 2, 5

Common Pitfalls to Avoid

• Never withhold RIG from previously unvaccinated persons based on time elapsed since exposure—treatment remains indicated regardless of delay 1, 2
• Never give RIG to previously vaccinated persons, as it inhibits the anamnestic response 2
• Never fail to infiltrate wounds with RIG when anatomically possible—rare prophylaxis failures have been reported when inadequate RIG was infiltrated at exposure sites 1
• Never use the gluteal area for vaccine injection, as this produces inadequate antibody titers 2