Rabies Transmission: Beyond Bites — Saliva, Transplants & Lab Exposure

Transmission Routes

Rabies virus (Lyssavirus) is transmitted via virus-laden saliva or neural tissue entering broken skin or mucous membranes.

1. Bite (Primary)

Puncture inoculates virus deep into muscle/nerve endings. Dogs = 99% human cases globally.

2. Non-Bite Exposures

• Licks on broken skin/mucosa: Scratches, abrasions, eyes, mouth.
• Scratches: Contaminated claws (grooming).
• Mucosal Splash: Saliva into eyes/nose/mouth.

3. Human-to-Human (Rare)

• Organ Transplantation: Corneal grafts (4 US cases 1978–2013), solid organs (kidney, liver, lung, heart) — donors with undiagnosed encephalitis.
• Laboratory Accidents: Aerosol, needlestick, mucosal exposure to high-titer virus.

4. NOT Transmitted By

• Blood transfusion (no viremia).
• Casual contact, fomites, urine/feces.
• Pasteurized milk (theoretical only).

Post-Exposure Prophylaxis (PEP)

• Category I (touching/feeding): None.
• Category II (nibbling, minor scratches): Vaccine only (4-dose: Days 0, 3, 7, 14).
• Category III (bites, licks on broken skin, mucous membrane): Vaccine + HRIG (20 IU/kg infiltrated around wound + IM).
• Previously Vaccinated: 2 doses (Days 0, 3); no HRIG.

Global Burden

~59,000 human deaths/year (95% Asia/Africa). Dog vaccination eliminates human rabies. One Health approach.