What is the risk of requiring post-exposure prophylaxis (PEP) if the animal does not have confirmed rabies?

Risk Assessment for Rabies Post-Exposure Prophylaxis When Animal Does Not Have Confirmed Rabies

Post-exposure prophylaxis (PEP) is not required if the animal is confirmed to be rabies-negative through laboratory testing, but should be initiated promptly if the animal cannot be tested or observed. 1, 2

Decision Algorithm for PEP Administration

Animal Type and Testing Status

1. Domestic Dogs, Cats, and Ferrets

   • If healthy and available for 10-day observation: Do not begin PEP unless animal develops clinical signs of rabies 2
   • If rabid or suspected rabid: Immediately begin PEP 2
   • If unknown (escaped): Consult public health officials 2

2. Wild Animals (Skunks, Raccoons, Foxes, and Bats)

   • Regarded as rabid unless proven negative by laboratory testing 2
   • Initiate PEP immediately unless:
     • Animal is available for testing and expeditious laboratory testing is being facilitated by public health authorities
     • Brain tissue has already tested negative 2

3. Small Rodents and Lagomorphs

   • Rarely infected with rabies and not known to transmit to humans 2
   • Consult local/state health department before deciding on PEP 2

Type of Exposure Assessment

1. Bite Exposure

   • Any penetration of skin by teeth requires risk assessment based on animal type 2

2. Non-bite Exposure

   • Scratches, abrasions, open wounds, or mucous membranes contaminated with saliva or neural tissue may require PEP 1, 2
   • PEP should be considered for bat exposures even when bites are not apparent if direct contact occurred 1

3. Non-exposures (PEP NOT indicated)

   • Petting a rabid animal 3
   • Contact with blood, urine, or feces of a rabid animal 3, 2
   • Contact of saliva with intact skin 2

Risk Factors Affecting PEP Decision

1. Regional Epidemiology

   • The likelihood of rabies in domestic animals varies by region 2
   • Higher risk in areas with known wildlife rabies reservoirs 4

2. Circumstances of Incident

   • Unprovoked attacks more likely indicate rabid animal than provoked attacks 2
   • Bites during feeding or handling attempts generally considered provoked 2

3. Vaccination Status of Animal

   • Properly immunized animals have minimal chance of developing and transmitting rabies 2

Practical Considerations

1. Timing of PEP

   • If animal testing is available, PEP can be delayed up to 48 hours while awaiting results 3
   • If testing confirms the animal is not rabid, PEP can be discontinued 3, 2

2. Special Case: Bat Exposures

   • PEP recommended for all persons with bite, scratch, or mucous membrane exposure to a bat 1
   • May be appropriate even without obvious bite when there is reasonable probability of exposure 1

3. Risk Threshold

   • Recent modeling studies suggest a risk threshold of 0.0004 (0.04%) for recommending PEP; exposures with lower probability may not require PEP 4

Common Pitfalls to Avoid

1. Delayed Decision-Making

   • Waiting too long to initiate PEP can be fatal if the animal was rabid
   • PEP should be started immediately for high-risk exposures, then discontinued if animal testing is negative 2

2. Overuse of PEP

   • Administering PEP for non-exposures (petting, contact with urine/feces) is unnecessary 3, 2
   • Small rodents rarely require PEP unless unusual circumstances exist 2

3. Underestimating Bat Exposures

   • Bat bites can be minor and difficult to recognize
   • PEP should be considered for any physical contact with bats when bite/scratch cannot be excluded 1, 2

By following these guidelines, healthcare providers can make appropriate decisions about rabies PEP administration, avoiding both unnecessary treatment and potentially fatal delays in necessary treatment.