lecture recording 3-11-2025

Introduction to Rabies

• Rabies virus travels rapidly to the brain after inoculation.

• Once in the brain, it replicates and moves to salivary glands, transmitting the virus in subsequent bites.

Reservoir Species

• Reservoir: a host harboring the rabies virus; often asymptomatic initially.

• Common reservoirs include:

  • Terrestrial carnivores: dogs, foxes, raccoons, skunks.

  • Bats, which are often seen as a higher risk for rabies transmission.

  • Cats: most reported domestic animals with rabies due to their outdoor lifestyle and feral colonies.

Incubation and Transmission of Rabies

• Incubation Period: Varies greatly, can be short or lengthy; closer bites to the brain lead to shorter incubation.

• Post-exposure prophylaxis (PEP) is possible if administered soon after exposure.

• Transmission occurs primarily through bites; no hematogenous spread. Some rare aerosol transmission has been documented.

Clinical Signs of Rabies

• Clinical signs are variable and depend on animal behavior and exposure history.

• Typical signs include:

  • Abnormal behavior based on normalcy (e.g., sudden aggression in previously friendly animals).

  • Altered phonation: unusual vocalizations or aggression.

  • Progressive paralysis and neurological symptoms.

• There are three phases:

  • Prodromal Phase: General, nonspecific symptoms.

  • Excitative Phase: Aggressive behavior changes.

  • Paralytic Phase: Severe paralysis leading to death.

Diagnosis of Rabies

• No antemortem test for rabies; diagnosis confirmed postmortem via brain sample submission.

• Immunofluorescent antibody testing and PCR are viable diagnostic methods.

Control and Prevention of Rabies

• Vaccination of domestic animals (cats, dogs) is mandated and crucial for control.

• Registration of pets helps monitor rabies exposure potential.

• Feral cat management and vaccination programs are significant for reducing spread.

• Education through rabies clinics encourages responsible pet ownership and vaccination compliance.

• Post-exposure measures include immediate wound cleaning and PEP vaccination schedules.

Implications for Veterinary Professionals

• Veterinarians and animal control personnel often vaccinated against rabies due to high exposure risk.

• Prompt recognition and action are vital in possible rabies cases, particularly with unclaimed animals, which may lead to euthanasia.

• Continuous vigilance and screening for rabies in suspected cases are crucial for public health.

Other Related Diseases

• Pseudorabies: Affects primarily pigs; acute neurological signs but not rabies.

• Prion Diseases (e.g., BSE, scrapie): Exhibits similar neurological signs but differ in etiology and transmission.

• Management includes biosecurity and vaccination in swine to prevent pseudorabies outbreaks.

• Prion diseases require strict control and reporting due to their fatal nature and lack of treatment options.

Diagnostic Techniques in Veterinary Medicine

• ELISA: Used for antigen detection; good for screening groups.

• PCR: Amplifies genetic material for more accurate diagnosis and is a gold standard test.

• AGID: More suitable for individual sick animals but less sensitive than ELISA.