Rabies Exposure Categories and Post-Exposure Prophylaxis
All rabies exposures should be categorized into three WHO categories (I, II, and III) based on the type and severity of contact, which directly determines whether and what type of post-exposure prophylaxis is required. 1
Exposure Categories
Category I: No Exposure
- Definition: Touching or feeding animals, contact with intact skin, or licks on intact skin 1
- Additional non-exposures: Contact with blood, urine, feces (guano), or petting a rabid animal 1
- PEP Required: None 1
- Rationale: Rabies virus cannot penetrate intact skin and requires introduction into wounds, cuts, or mucous membranes 1
Category II: Minor Exposure
- Definition: Nibbling of uncovered skin without bleeding, minor scratches or abrasions without bleeding, or licks on broken skin 1
- PEP Required:
Category III: Severe Exposure
Definition:
- Any penetration of skin by teeth (bite exposure) 1
- Contamination of mucous membranes with saliva 1
- Contamination of open wounds, abrasions, or scratches with saliva or potentially infectious material (neural tissue) 1
- Special consideration: ANY physical contact with bats when bite or mucous membrane exposure cannot be excluded, including finding a bat in a room with a sleeping person, child, mentally disabled person, or intoxicated person 4
PEP Required:
- Immediate thorough wound washing with soap and water for 15 minutes 2
- Human Rabies Immune Globulin (HRIG): 20 IU/kg body weight 3, 5
- Full dose should be thoroughly infiltrated in and around ALL wounds if anatomically feasible 4
- Any remaining volume injected IM at a site distant from vaccine administration 4
- Must be given within 7 days of first vaccine dose (preferably day 0) 5, 4
- Never administer in same syringe or same anatomical site as vaccine 4
- Rabies Vaccine Series:
Risk Assessment Factors Beyond Category
Animal Species Considerations 5, 4
- High-risk animals (always consider PEP): Bats, skunks, raccoons, foxes, coyotes, bobcats 5, 4
- Variable risk: Dogs, cats, ferrets (depends on regional epidemiology and animal availability for 10-day observation) 5, 4
- Low risk (rarely require PEP): Small rodents (squirrels, hamsters, guinea pigs, gerbils, chipmunks, rats, mice), rabbits, hares 5, 4
- Exception: Woodchucks and beavers should be considered potential rabies exposures 4
Wound Severity Factors 6, 7
- Highest risk exposures: Multiple wound sites, bites to head/face/neck, deep wounds, wounds in highly innervated areas 6, 7
- Common pitfall: Delaying PEP for severe head and neck wounds increases risk of breakthrough infection 3, 7
- Bat exposures: Even minor, undetected bites carry significant risk and warrant full Category III treatment 3, 4
Summary Table of Categories
| Category | Type of Contact | Wound Washing | Vaccine | Immunoglobulin (HRIG) |
|---|---|---|---|---|
| I | Touching/feeding animals, licks on intact skin | Not required | None | None |
| II | Nibbling uncovered skin, minor scratches without bleeding, licks on broken skin | Yes (15 min with soap/water) | Yes (5 doses if unvaccinated; 2 if vaccinated) | None |
| III | Bites, scratches with bleeding, mucous membrane contamination, bat contact when bite cannot be excluded | Yes (15 min with soap/water) | Yes (5 doses if unvaccinated; 2 if vaccinated) | Yes (20 IU/kg, infiltrate wounds) |
Critical Pitfalls to Avoid
- Never administer vaccine in gluteal area - deltoid only in adults and older children 3, 4
- Never delay PEP for severe head/neck wounds - these carry highest mortality risk 3, 7
- Never fail to recognize bat exposures - any physical contact with bats when bite cannot be excluded requires full Category III treatment 4
- Never administer HRIG after day 7 - it may blunt the immune response to vaccine 5, 4
- Never give HRIG to previously vaccinated persons - it interferes with anamnestic response 1, 3