Rabies Incubation Period Following Greater Bandicoot Rat Bite
Small rodents including rats are almost never infected with rabies and have not been known to transmit rabies to humans, so post-exposure prophylaxis is typically not indicated for rat bites unless highly unusual circumstances exist. 1
Risk Assessment for Rodent Bites
The CDC states that small rodents (rats, mice, squirrels, hamsters, guinea pigs, gerbils, chipmunks) are almost never found to be infected with rabies and have not been known to transmit rabies to humans. 1
Contact your state or local health department before initiating rabies PEP for any rodent bite, as they can provide guidance based on local rabies epidemiology. 1
The exception among rodents is woodchucks, which accounted for 93% of 371 rabies cases among rodents reported to CDC from 1990-1996 in areas where raccoon rabies was enzootic. 1
Incubation Period (If Rabies Transmission Occurred)
While rat transmission is extraordinarily rare, if rabies were transmitted, the incubation period would follow standard patterns:
The incubation period in humans typically ranges from 1-3 months after exposure, but can range from days to over 1 year. 2
In domestic animals, the incubation period is generally 3-12 weeks but can range from several days to months, rarely exceeding 6 months. 2
In a study of 177 human rabies cases, 61.8% developed disease between 30-120 days after exposure, and 90% developed disease within 6 months. 3
The incubation period is shorter when bites occur on the head, neck, face, or multiple body parts, and when bites occur on uncovered parts of the body. 3
Immediate Wound Management Steps
Even though rabies PEP is not indicated for typical rat bites, proper wound care is essential to prevent bacterial infection:
Immediately and thoroughly wash all bite wounds with soap and water for 15 minutes, as this markedly decreases the risk for bacterial infection. 1
Consider tetanus prophylaxis based on the patient's vaccination history. 1
Evaluate the need for antibiotic prophylaxis to prevent bacterial infection from the bite wound. 1
Assess for serious injury such as nerve or tendon laceration. 1
Post-Exposure Prophylaxis Protocol (If Indicated)
If highly unusual circumstances exist (rat displaying obvious neurological symptoms, documented rabies in rodents in your geographic area), defer to local public health guidance. 1 If PEP is deemed necessary:
For Previously Unvaccinated Persons:
Administer 4 doses of rabies vaccine (HDCV or PCECV) intramuscularly on days 0,3,7, and 14, plus human rabies immune globulin (HRIG) at 20 IU/kg on day 0. 2, 4
Inject vaccine in the deltoid muscle for adults and older children, or anterolateral thigh for young children—never use the gluteal area as this produces inadequate antibody response. 2, 4
Infiltrate the full calculated dose of HRIG around and into the wound(s) if anatomically feasible, with any remaining volume injected intramuscularly at a site distant from vaccine administration. 4
HRIG should not be administered in the same syringe or at the same anatomical site as the vaccine. 4
For Previously Vaccinated Persons:
For Immunocompromised Persons:
Administer 5 doses of vaccine on days 0,3,7,14, and 28, plus HRIG at 20 IU/kg on day 0. 4
Obtain serologic testing 1-2 weeks after the final dose to confirm adequate antibody response. 4
Critical Timing Considerations
PEP should be initiated as soon as possible after exposure, ideally within 24 hours, though treatment remains indicated even if weeks or months have elapsed since exposure. 4
There is no absolute cutoff for initiating PEP, as rabies is nearly 100% fatal once clinical symptoms develop. 2, 5
Once clinical rabies develops, the disease progresses rapidly to death, with 93.4% of patients dying within 5 days of symptom onset. 3