Animal Bite Infections: Zoonotic Risks, Transmission, and Immediate Management

Animal bites inoculate pathogens directly into tissue. The resulting infections are contagious in the epidemiologic sense—transmissible from animal to human. Human-to-human transmission from bite wounds is vanishingly rare (theoretical rabies via transplant).

Key Zoonotic Bite Pathogens

Pathogen	Source	Clinical Syndrome
Rabies virus	Dog, bat, raccoon, skunk, fox	Encephalitis — 100% fatal once symptomatic; PEP urgent
Capnocytophaga canimorsus	Dog/cat	Sepsis, gangrene, meningitis — immunocompromised at highest risk
Pasteurella multocida	Cat (75%), dog (50%)	Rapid cellulitis (12–24h), tenosynovitis, osteomyelitis
Bartonella henselae	Cat scratch/bite	Cat-scratch disease: regional lymphadenopathy, fever
Herpes B virus (Macacine HV-1)	Macaque monkeys	Ascending myelitis, encephalitis — medical emergency
Francisella tularensis	Rabbit, rodent	Tularemia: ulceroglandular, typhoidal
Yersinia pestis	Rodent flea/bite	Plague: bubonic, septicemic, pneumonic
Streptobacillus moniliformis	Rat bite	Rat-bite fever: fever, rash, arthralgia

Immediate Post-Bite Management

1. Irrigate copiously: Soap + water, 15 minutes (reduces rabies viral load 90%+).
2. Seek medical evaluation: Rabies risk assessment (animal species, behavior, vaccination, geography) → PEP decision.
3. Tetanus prophylaxis: Tdap/Td if >5 yrs (dirty wound) or >10 yrs (clean).
4. Antibiotic prophylaxis (high-risk bites): Deep puncture, cat bites, hand/face/genital, immunocompromised, prosthetic joint. Amoxicillin/clavulanate 3–5 days.
5. Report: Animal control/public health — quarantine (10 days dog/cat), testing (wildlife).

Rabies PEP

• Unvaccinated: HRIG 20 IU/kg (infiltrate wound + IM) + HDCV/PCEC vaccine days 0, 3, 7, 14.
• Previously vaccinated: Vaccine days 0, 3 only (no HRIG).

Every bite is a potential rabies exposure until proven otherwise. When in doubt, give PEP—rabies is 100% preventable, 100% fatal if missed.