What is the recommended post-exposure prophylaxis (PEP) regimen, including rabies vaccine, for a child exposed to a potential rabies risk through a cat scratch?

Rabies Post-Exposure Prophylaxis for Cat Scratch in Children

Direct Recommendation

For a child with a cat scratch that potentially exposed them to rabies, initiate full post-exposure prophylaxis (PEP) immediately if the cat is unavailable for testing, rabid, or suspected rabid—this consists of thorough wound washing, human rabies immune globulin (HRIG) at 20 IU/kg infiltrated into and around the wound, and a 4-dose rabies vaccine series (days 0,3,7,14) administered intramuscularly in the deltoid or anterolateral thigh. 1, 2, 3

Understanding Cat Scratch as Rabies Exposure

• Cat scratches contaminated with saliva or neural tissue from a potentially rabid cat constitute a nonbite exposure requiring PEP evaluation. 1

• The rabies virus is transmitted when introduced into open wounds, scratches, abrasions, or mucous membranes through saliva or other infectious material. 1

• If the material containing virus is dry, it is considered noninfectious and does not warrant prophylaxis. 1

• Petting a rabid animal or contact with blood, urine, or feces alone does not constitute exposure and is not an indication for prophylaxis. 1, 4

Risk Assessment Algorithm

When to Initiate PEP for Cat Scratches:

Immediate PEP is indicated if: 1, 3, 4

• The cat is confirmed rabid by laboratory testing
• The cat is suspected rabid based on clinical signs or behavior
• The cat is unavailable for observation or testing
• The cat dies or develops rabies during the 10-day observation period

PEP can be withheld if: 3, 4

• The cat is healthy and available for 10-day observation, and remains healthy throughout
• The cat tests negative for rabies by appropriate laboratory testing (direct fluorescent antibody test)

Critical caveat: In areas where rabies is enzootic in cats, or if the exposure was severe (deep scratches on face/head), strongly consider initiating PEP immediately rather than waiting for observation results. 1

Complete PEP Regimen for Previously Unvaccinated Children

Immediate Wound Management (Within Minutes):

• Wash all wounds and scratches thoroughly with soap and water for 15 minutes—this single intervention is perhaps the most effective measure for preventing rabies. 2, 5, 3

• Apply a virucidal agent such as povidone-iodine solution if available. 2, 3

• Provide tetanus prophylaxis and bacterial infection control as indicated. 5, 3

HRIG Administration (Day 0):

• Administer HRIG at exactly 20 IU/kg body weight on day 0, ideally simultaneously with the first vaccine dose. 2, 3

• Infiltrate the full calculated dose around and into the wound(s) if anatomically feasible; inject any remaining volume intramuscularly at a site distant from vaccine administration. 2, 3

• Never administer HRIG in the same syringe or at the same anatomical site as the vaccine. 2, 3

• Do not exceed 20 IU/kg, as higher doses suppress active antibody production. 2, 3

• HRIG can be administered up to and including day 7 if initially missed, but is contraindicated after day 7 when active antibody production has begun. 2, 5, 3

Vaccine Administration:

• Administer 1.0 mL of rabies vaccine (HDCV or PCECV) intramuscularly on days 0,3,7, and 14. 1, 2, 3

• For young children, inject in the anterolateral thigh; for older children, use the deltoid muscle. 2, 3

• Never use the gluteal area—this produces inadequate antibody response and has been associated with vaccine failures. 2, 3

• Children receive the same 1.0 mL dose volume as adults. 2, 3

Special Considerations for Pediatric Patients

Immunocompromised Children:

• Immunocompromised children require a 5-dose vaccine regimen (days 0,3,7,14,28) plus HRIG at 20 IU/kg, even if previously vaccinated. 2, 3

• Serologic testing 1-2 weeks after the final dose is mandatory to confirm adequate antibody response (≥1:5 dilution by RFFIT). 2, 3

• Conditions requiring the 5-dose regimen include HIV, chronic lymphoproliferative leukemia, corticosteroid therapy, and other immunosuppressive medications or illnesses. 2

Previously Vaccinated Children:

• Children who completed a prior rabies vaccination series require only 2 doses of vaccine (days 0 and 3) and do NOT need HRIG. 2, 5, 3

• Administering HRIG to previously vaccinated persons is a critical error that suppresses the memory immune response. 2

Timing Considerations

• PEP is a medical urgency, not a medical emergency, but should be initiated as soon as possible after exposure—ideally within 24 hours. 2, 6

• There is no absolute cutoff for initiating PEP; treatment should begin immediately upon recognition of exposure even if weeks or months have elapsed, provided clinical rabies symptoms have not developed. 2, 5, 6

• Rabies incubation periods typically range from 1-3 months but can extend from days to over a year. 2, 6

• Delays of a few days for individual vaccine doses are unimportant and do not compromise protection. 2

Common Pitfalls to Avoid

• Do not withhold PEP while waiting for animal observation results if the exposure occurred in a rabies-endemic area or involved high-risk circumstances. 2, 6

• Do not administer vaccine in the gluteal area under any circumstances. 2, 3

• Do not give HRIG to previously vaccinated children—this suppresses the anamnestic response. 2, 3

• Do not exceed 20 IU/kg for HRIG dosing. 2, 3

• Do not delay wound washing—this should be performed immediately, before any other intervention. 2, 5

Evidence Supporting Cat Scratch as Rabies Risk

• A documented case of fatal paralytic rabies following a category III cat scratch on the face occurred in a 15-year-old girl who received intradermal vaccine but no HRIG, confirming that cat scratches can transmit rabies. 7

• Rabies virus is shed in cat saliva days before clinical signs appear and can be transmitted through scratches that contaminate wounds with infected saliva. 8

• Multiple rabies exposures requiring extensive public health investigation have occurred from cats in public settings, including pet stores and petting zoos. 1

When PEP Can Be Discontinued

• If the cat remains healthy during a 10-day observation period, PEP can be discontinued. 3, 4

• If laboratory testing (direct fluorescent antibody test) confirms the cat is not rabid, PEP can be discontinued. 1, 3, 4

• Dogs, cats, and ferrets do not shed rabies virus in saliva more than 10 days before showing clinical signs, which is the rationale for the 10-day observation period. 5