What are the indications for anti‑rabies prophylaxis?

Indications for Anti-Rabies Prophylaxis

Anti-rabies prophylaxis is indicated for two distinct scenarios: pre-exposure prophylaxis for high-risk individuals and post-exposure prophylaxis based on WHO exposure categories, with Category III exposures (bites, scratches with bleeding, or mucous membrane contamination) requiring immediate full prophylaxis with both vaccine and immunoglobulin. 1

Pre-Exposure Prophylaxis Indications

Pre-exposure vaccination should be administered to individuals at continuous or frequent risk of rabies exposure 2:

• High-risk occupational groups including veterinarians, animal handlers, rabies laboratory workers, diagnosticians, and rabies researchers require pre-exposure prophylaxis 2, 3
• Cave explorers and spelunkers who may encounter bats in endemic areas 2, 3
• Travelers planning to spend more than 1 month in countries where rabies is a constant threat 2
• Persons whose vocations or avocations bring them into contact with potentially rabid animals (skunks, raccoons, bats, foxes) 2

The pre-exposure regimen consists of three 1.0 mL intramuscular doses of HDCV or PCECV in the deltoid area on days 0,7, and 21 or 28 1, 4. Pregnancy is not a contraindication if substantial exposure risk exists 2.

Post-Exposure Prophylaxis Indications by WHO Category

Category I Exposure (No Prophylaxis Required)

• Touching or feeding animals with intact skin 1
• Licks on intact skin 1
• Contact with animal blood, urine, or feces 5

No treatment is indicated for Category I exposures 1.

Category II Exposure (Vaccine Only)

• Nibbling of uncovered skin without bleeding 1
• Minor scratches or abrasions without bleeding 1
• Licks on broken skin 1

Administer vaccine series only—no immunoglobulin required 1.

Category III Exposure (Full Prophylaxis Required)

• Any penetration of skin by teeth (bite) 1, 5
• Scratches or abrasions with bleeding 1
• Contamination of mucous membranes with saliva (eyes, nose, mouth) 1, 5
• Contamination of open wounds with saliva or neural tissue 1, 5
• Any bat contact when a bite cannot be excluded 1

Category III exposures require immediate wound washing, human rabies immune globulin (HRIG) at 20 IU/kg, and complete vaccine series 1, 6.

Animal Species Risk Assessment

The decision to initiate post-exposure prophylaxis depends critically on the animal species involved 2, 5:

• High-risk wild carnivores (raccoons, skunks, foxes, coyotes, bobcats) should be considered rabid unless proven otherwise—initiate prophylaxis immediately 2, 1, 5
• Bats are extremely high-risk; any bat contact warrants prophylaxis if a bite cannot be excluded 1
• Domestic dogs, cats, and ferrets that are healthy and available for 10-day observation do not require immediate prophylaxis—begin only if animal develops clinical signs during observation 5
• Rabid or suspected rabid domestic animals require immediate prophylaxis 5
• Small rodents (squirrels, rats, mice, hamsters, guinea pigs) and lagomorphs (rabbits, hares) rarely transmit rabies—consult local health department before initiating prophylaxis 2, 5
• Woodchucks are the exception among rodents and should be treated as high-risk 2

Circumstances Influencing the Decision

Beyond exposure category and animal species, consider 2, 5:

• Unprovoked attacks are more likely to indicate a rabid animal than provoked attacks 2, 5
• Geographic location and regional epidemiology—rabies prevalence varies significantly by region 5
• Vaccination status of the biting animal—a properly immunized animal has minimal chance of transmitting rabies 5
• Availability of the animal for testing—if the animal can be captured and tested expeditiously, prophylaxis may be delayed pending results 5

Modified Prophylaxis for Previously Vaccinated Persons

Individuals who have previously received complete pre-exposure or post-exposure rabies vaccination require simplified post-exposure prophylaxis 2, 1:

• Two doses of vaccine only (1.0 mL intramuscularly on days 0 and 3) 2, 1
• No immunoglobulin should be administered, as it may inhibit the anamnestic response 2, 1

This applies to persons who have received a complete HDCV, PCECV, or RVA series and had documented adequate antibody response 2.

Special Populations

Immunocompromised Patients

• Require 5-dose vaccine regimen (days 0,3,7,14,28) plus HRIG at 20 IU/kg, even if previously vaccinated 6
• Mandatory serologic testing to confirm adequate antibody response 2, 6
• Immunosuppressive agents should not be administered during post-exposure prophylaxis unless essential 2

Pregnancy

• Pregnancy is not a contraindication to either pre-exposure or post-exposure prophylaxis 2, 6
• The potential consequences of inadequately treated rabies exposure far outweigh theoretical risks 2, 6

Neonates

• Receive the same weight-based regimen as adults (HRIG 20 IU/kg plus vaccine series) 7
• No age-based contraindications or dose modifications 7

Critical Timing Considerations

Initiate post-exposure prophylaxis as soon as possible after exposure—delays of even hours matter significantly 6. There is no absolute cutoff beyond which prophylaxis should be withheld 6. However, the urgency varies:

• Severe wounds to the face, head, neck, hands, or fingers require immediate prophylaxis without waiting for animal testing 6, 5
• Multiple deep puncture wounds warrant immediate treatment 5

Common Pitfalls to Avoid

• Failure to recognize bat bites, which may be minor and undetected—any bat contact in a sleeping person or young child warrants prophylaxis 1
• Delaying prophylaxis for severe facial or head wounds while awaiting animal testing 1
• Administering vaccine in the gluteal area, which produces inadequate antibody response and has been associated with vaccine failures 6
• Exceeding 20 IU/kg of HRIG, as higher doses suppress active antibody production 6
• Administering HRIG to previously vaccinated persons, which interferes with the anamnestic response 2, 1
• Interrupting prophylaxis due to mild local reactions, which can be managed with anti-inflammatory agents 6

Human rabies is nearly 100% fatal once clinical symptoms develop, but post-exposure prophylaxis is nearly 100% effective when administered promptly and correctly 6, 3.