ISSN 2398-2969      

Rabies disease

icanis

Introduction

  • Cause: viral disease of the central nervous system (CNS).
  • Signs: 'furious ' and 'dumb' forms.
  • All mammals susceptible (to a variable extent). Birds less susceptible.
  • Reservoir hosts vary with country, but mainly include dogs, cats, foxes, bats, raccoons and wolves.
  • Treatment: none.
  • Diagnosis: signs, history of exposure to the virus, confirmation on examination of brain at histopathology.
  • Prognosis: grave/hopeless.

Pathogenesis

Etiology

Predisposing factors

General

  • All mammals susceptible to infection (to a variable extent). To a lesser degree birds can be susceptible too.

Specific

  • Bite/scratch from infected animal.
  • Contact with saliva from infected animal, especially if skin damaged.

Pathophysiology

  • Transmission by bite/scratch or accidental break in skin.
  • Primary replication in muscle fibers at site of inoculation → virus aggregates around proprioreceptor nerve endings → virus binds to nicotinic acetylcholine receptors and enters axon sheath of afferent nerve within 5 hours → virus migrates (retrograde axoplasmic flow) to spinal ganglion at up to 3 mm/h → multiplies in spinal ganglion (or hippocampus) → virus enters dorsal horn of spinal cord → ependymal cells → brain → centrifugal spread down cranial nerves → salivary glands (and lungs/kidneys) → multiplication → excretion in saliva in 50% of infected dogs (others die before this stage).
  • Combined active and passive immunization shortly after exposure eliminates virus before it reaches CNS.
  • Some exposed dogs do not develop disease (immunity?).

Timecourse

  • Incubation period depends on:
    • Distance of site of inoculation from CNS.
    • Severity of bite.
    • Dose of virus inoculated.
  • Incubation 5 days-12 months (usually less than 3 months).
  • Death within 5-15 days of onset of signs.

Epidemiology

  • Dog requires high virus dose for infection ('intermediate susceptibility'), puppies more susceptible than adults.
  • Infection by inhalation very rare.
  • Reservoir host varies with location: include Canidae, Mustelidae and Chiroptera (bats).
  • Endemic in racoons, skunks (USA), vampire bats (Central America), mongoose (S. Africa - parts of Caribbean), red fox (Europe), Jackals (Africa).
  • Dog rabies is most significant in zoonosis.
  • Bats may have subclinical infection with persistent viremia.
  • Skunks and foxes may recover from infection.
  • Some dogs have mild symptoms, recover, and remain as persistent excretors.
  • Some countries free of rabies (see above).
  • Virus survives only when numerous susceptible hosts available in close contact.

Diagnosis

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Treatment

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Prevention

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Outcomes

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Further Reading

Publications

Refereed papers

Other sources of information

  • Beynon P H & Edney A T B (1995) Rabies in a Changing World. In: Proceedings of a Joint Symposium held at the Royal Society of Medicine, London. 3rd May. Cheltenham: British Small Animal Veterinary Association.

Can’t find what you’re looking for?

We have an ever growing content library on Vetlexicon so if you ever find we haven't covered something that you need please fill in the form below and let us know!

 
 
 
 

To show you are not a Bot please can you enter the number showing adjacent to this field

 Security code