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Microbiology · Other RNA viruses

Rabies virus !

  • Virus
  • Enveloped
  • Exam priority: high

A virus passed in the saliva of infected animals that climbs the nerves to the brain. Once symptoms start it is almost always fatal, but it is preventable.

Updated 2026-11-01

Also called: rabies lyssavirus

At a glance

Shape
Bullet-shaped
Genome
Single-stranded, negative-sense, non-segmented RNA
Envelope
Enveloped
Family
Rhabdoviridae, genus Lyssavirus
Size
About 75 by 180 nm

Morphology

  • Enveloped, bullet-shaped virus with glycoprotein G spikes
  • Glycoprotein G is the target of vaccine-induced neutralizing antibodies

Transmission

  • Saliva of an infected animal through a bite, scratch or lick of mucosa or wounds
  • Worldwide, dogs cause the great majority of human cases
  • In the Americas, blood-feeding bats are now the main source
  • Very rarely by organ transplant

Reservoir: Dogs (canine variants); Vampire bats (Desmodus rotundus) and insect-eating bats; Foxes, cats and other mammals as hosts

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Virulence factors

  • Replicates in muscle at the bite site and binds the nicotinic acetylcholine receptor
  • Travels by retrograde axonal transport to the central nervous system, out of reach of antibodies
  • Encephalitis with Negri bodies (cytoplasmic inclusions) in hippocampal and cerebellar neurons
  • Then spreads outward to salivary glands and other organs

Diseases it causes

  • Human rabies: furious (encephalitic) and paralytic forms Rabies →

Clinical picture

  • Usual incubation 2 to 3 months (one week to one year), shorter when the wound is closer to the head
  • Prodrome: fever and pain, tingling or burning at the wound site
  • Furious form: agitation, hydrophobia, aerophobia, hypersalivation, hallucinations
  • Paralytic form (about 20%): ascending paralysis from the wound, often misdiagnosed
  • Coma and death in almost 100% once symptoms appear

Diagnosis

  • In life: RT-PCR on saliva, nuchal skin biopsy (antigen in follicular nerve fibres) and antibodies in serum and CSF
  • After death: direct immunofluorescence on brain tissue, Negri bodies
  • In the animal: 10-day observation of the dog or cat or brain testing

Treatment

There is no effective treatment once symptoms appear: only palliative care. Post-exposure prophylaxis does work: immediate, thorough washing of the wound with soap and water, a series of human rabies vaccine and rabies immunoglobulin infiltrated into the wound for severe exposures.

Drug class only; doses and regimens are set by the clinician from the current guideline.

Prevention

  • Yearly vaccination of dogs and cats
  • Post-exposure prophylaxis by risk classification
  • Pre-exposure prophylaxis for vets, lab staff, cavers and workers in bat areas
  • Education not to handle bats or wild animals

Vaccine: Inactivated cell-culture human rabies vaccine, which Colombia's public system provides free for post-exposure prophylaxis, together with rabies immunoglobulin.

Test yourself

Think of the answer, then tap the question to see it.

How does rabies virus get from the bite to the brain?

By retrograde axonal transport along peripheral nerves.

What are the components of post-exposure prophylaxis for a severe exposure?

Immediate washing of the wound with soap and water, a rabies vaccine series and rabies immunoglobulin infiltrated into the wound.

Which neuronal inclusions are typical of rabies?

Negri bodies, eosinophilic cytoplasmic inclusions in hippocampal neurons and Purkinje cells.

What is now the main source of human rabies in the Americas?

Bats, especially blood-feeding bats; dog rabies is largely controlled by vaccination.

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Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: Rabies (World Health Organization (WHO), 2025); Patient Care for Preventing Rabies (CDC, 2025); Appendix A: Type and Duration of Precautions Recommended for Selected Infections and Conditions (CDC, 2024).

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Representative model, for educational purposes only.