Rabies in Animals

Important Concepts

• Rabies: Fatal viral zoonosis causing acute, progressive encephalitis.

• Transmission: Via saliva through bites, open wounds, or mucous membranes.

• Incubation Period: Variable; generally 3-12 weeks in domestic animals.

• Clinical Signs: Include behavior changes, paralysis, seizures, and rapid progression to death.

Infectious Agents

• Genus Lyssavirus: Rabies virus is the primary agent, with multiple variants in wild reservoirs (e.g., raccoons, skunks, bats).

Clinical Changes

• Early Signs: Behavioral changes such as aggression or lethargy.

• Advanced Signs: Paralysis, cranial nerve deficits, ataxia, seizures, and altered vocalizations.

Pathological Changes

• CNS Tissue: Viral presence confirmed via direct fluorescent antibody test.

• Peripheral Tissues: Virus spreads from the bite site to the brain.

Diagnostic Procedures

• Standard Test: Direct fluorescent antibody test on CNS tissue.

• Serology: Not reliable for diagnosing current rabies infection but useful for verifying vaccination status.

Prevention and Control

• Vaccination:

  • Routine vaccination of domestic animals, especially dogs, cats, and ferrets.

  • Annual or triennial boosters depending on the vaccine.

• Public Health Measures:

  • Stray animal control and public education.

  • Coordination among veterinary and public health authorities.

  • Reporting and surveillance systems to track cases and variants.

Treatment

• Post-Exposure Prophylaxis (PEP): Essential for exposed humans; includes wound care, rabies immune globulin, and vaccination.

• No Effective Antiviral: Once clinical signs appear, rabies is almost universally fatal.

Rabies in Wildlife

• Control Measures:

  • Oral vaccination programs for wild reservoirs.

  • Avoidance of contact and public warnings.

• Surveillance: Regular monitoring and testing of wildlife populations.

Recommendations for Veterinarians

• Vaccination Protocols:

  • Initial vaccination at 3 months, followed by boosters.

  • Booster vaccines immediately after exposure for vaccinated animals.

• Handling Exposures:

  • Quarantine and observation periods for exposed animals.

  • Immediate euthanasia of unvaccinated animals exposed to rabies.

Rabies Management in Specific Scenarios

• Domestic Animals: Strict quarantine and immediate vaccination for exposed animals.

• Human Exposure: Quarantine and testing of the biting animal, post-exposure treatment for humans.

• Disaster Response: Ensure rabies vaccination and control measures in displaced animal populations.

Research and Future Directions

• Needs:

  • Better understanding of viral shedding in livestock.

  • Improved diagnostic tools and vaccines.

  • Continued surveillance and reporting to track epidemiological trends.

Rabies Post-Exposure Prophylaxis (PEP)

Important Concepts

• PEP Regimen: Involves wound washing, human rabies immune globulin (HRIG), and a series of rabies vaccines.

• Wound Care: Immediate and thorough cleaning with soap and water or povidone-iodine solution significantly reduces rabies risk.

• Rabies Vaccine: Administered at days 0, 3, 7, and 14; a fifth dose on day 28 for immunocompromised individuals.

• HRIG: Given once at the start, infiltrated around the wound, and not mixed with the vaccine.

Infectious Agents

• Rabies Virus: A deadly virus requiring immediate post-exposure treatment to prevent infection.

Clinical Changes

• No Immediate Signs: Rabies PEP is initiated before symptoms appear, as the disease is almost always fatal once symptoms develop.

Pathological Changes

• Virus Spread: Through nervous system tissues, from the site of exposure to the brain.

Treatment

• Non-Immunized Individuals:

  • Wound cleaning.

  • HRIG (20 IU/kg) infiltrated around the wound.

  • Rabies vaccine at specified intervals.

• Previously Immunized Individuals:

  • Wound cleaning.

  • Two doses of rabies vaccine on days 0 and 3; no HRIG.

Additional Details

• Vaccine Administration: Avoid the gluteal area to ensure efficacy.

• HRIG Administration: Given within 7 days of exposure, ideally not after the third vaccine dose.

For more detailed information, please visit the CDC's Rabies Post-exposure Prophylaxis page.