What is the post-exposure prophylaxis (PEP) for rabies after a possum bite or scratch?

Post-Exposure Prophylaxis for Rabies After a Possum Bite or Scratch

Possums have an extremely low risk of carrying rabies, and post-exposure prophylaxis (PEP) is generally not indicated following a possum bite or scratch unless the animal was exhibiting unusual behavior consistent with rabies. 1

Risk Assessment for Possum Exposures

• Possums are considered to have an extremely low risk for rabies transmission, similar to other rodents and lagomorphs (rabbits and hares) 1
• The FDA rabies post-exposure prophylaxis guide specifically states that "In most geographical areas bites of squirrels, hamsters, guinea pigs, gerbils, chipmunks, rats, mice, other rodents, rabbits, and hares almost never require antirabies post-exposure prophylaxis" 1
• Local and state public health officials should be consulted on questions about the need for rabies prophylaxis following possum bites 1

Decision Algorithm for Possum Bite/Scratch Management

1. Immediate wound care:

   • Thoroughly clean all bite wounds and scratches with soap and water immediately 2
   • If available, irrigate with a virucidal agent such as povidone-iodine solution 2
   • Consider tetanus prophylaxis and measures to control bacterial infection as indicated 2

2. Assess the possum and circumstances:

   • Was the attack provoked or unprovoked? (Unprovoked attacks are more likely to indicate rabies) 2
   • Was the possum exhibiting abnormal behavior or signs of illness? 2
   • Is rabies present in possums in your geographic region? (Consult local public health officials) 1

3. Consult local public health authorities:

   • Local and state public health officials should be consulted to determine the need for rabies PEP following possum bites 1
   • They will have the most current information about rabies epidemiology in your area 2

If PEP is Recommended (Unusual Circumstances)

If local public health authorities recommend PEP based on unusual circumstances or risk factors:

1. For previously unvaccinated persons:

   • Human Rabies Immune Globulin (HRIG): 20 IU/kg body weight 2
     • Infiltrate the full dose around and into the wound(s) if anatomically feasible 2
     • Inject any remaining volume IM at a site distant from vaccine administration 2
   • Vaccine: Human diploid cell vaccine (HDCV) or purified chick embryo cell vaccine (PCECV) 2
     • 1.0 mL, IM (deltoid area for adults/older children; outer thigh for younger children) 2
     • Administer on days 0,3,7, and 14 2
     • For immunocompromised patients, add a fifth dose on day 28 2

2. For previously vaccinated persons:

   • No HRIG needed 2
   • Vaccine: HDCV or PCECV 1.0 mL, IM (deltoid area), on days 0 and 3 only 2

Important Considerations

• Rabies is virtually 100% fatal once clinical symptoms develop, but is preventable with proper PEP 3
• PEP is highly effective when administered promptly and properly 4
• The decision to administer PEP should be based on a thorough risk assessment in consultation with public health authorities 2
• Wound cleansing alone has been shown to markedly reduce the likelihood of rabies in animal studies 2
• Unnecessary PEP should be avoided through proper risk assessment 5

Special Note on Possums and Rabies

• Possums have a naturally lower body temperature than many mammals, which makes them highly resistant to rabies virus infection 5
• While theoretically possible, rabies in possums is extremely rare, and documented cases of rabies transmission from possums to humans are virtually non-existent 1