Lapis ISSN 2398-2969

Rabies virus

Synonym(s): Lyssavirus

Contributor(s): Alana Shrubsole-Cockwill, Susan Dawson, Anna Meredith

Introduction

Classification

Taxonomy

  • Family: Rhabdoviridae.
  • Genus:Lyssavirus.
  • RNA virus.
  • Single-stranded, negative-sense.

Etymology

  • Gk:rhabdos- rod; refers to the shape of the virus - often described as bullet-shaped.
  • Gk:lyssa- rage, fury.

Active Forms

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Clinical Effects

Epidemiology

Habitat

  • Important reservoir hosts are dogs, cats, foxes, skunks, wolves, raccoons, mongoose, badgers, coyotes and bats, depending on region. Once infected, these animals carry infectious virus in their salivary glands.

Lifecycle

  • Following transmission (usually by biting), rabies virus persists in local muscle tissue for hours or days.
  • Rabies remains cell associated as it is not especially cytolytic.
  • Initial replication occurs in muscle cells, at the site of the bite (known as the incubation phase). There are minimal or no symptoms.
  • The length of the incubation phase is determined by the dose of rabies virus and the nearness of the bite to the CNS and brain. 
  • Virus is taken up by motor nerve endings in peripheral nerves and spreads to the CNS and brain (known as the prodrome phase).
  • Once the virus infects the brain, the traditional symptoms ensue (known as the neurological phase):
  • During the neurological phase, the virus then spreads to other organs, eg salivary glands, skin and tonsils.
  • Rabies virus does not elicit an antibody response until the latter stages of the disease, ie after it has spread to the CNS.
  • Antibodies can stop the development of the virus and disease; as a result of the long incubation periods, immunization is an effective post-exposure treatment, if it's administered before the virus reaches the CNS.

Transmission

Direct transmission

  • Saliva containing live rabies virus enters via animal bite, open wound or contact with mucous membrane.

Indirect transmission

  • Inhalation or aerosolized rabies virus, eg bat caves or laboratory setting.

Person-to-person transmission

  • Rarely reported.
  • Occurs via organ and corneal transplantation.

Pathological effects

  • Causes rabies   Rabies  .
  • Vaccination results in circulating neutralizing antibodies within 3 weeks.
  • T helper cells are important for developing immunity.
  • Immune response from vaccination can prevent rabies, but response to natural infection does not aid in recovery.
  • Bite of rabid animal carrying virus in saliva -> persists in local muscle tissue -> spreads in nerve cell axons -> replication in spinal cord -> spreads to brain -> non-purulent polioencephalomyelitis with perivascular cuffing.

Other Host Effects

  • Classical rabies (encephalitic rabies): hyperexcitability and hydrophobia.
  • Dumb rabies (paralytic rabies): muscle flaccidity.
  • Non-classical rabies: neuropathic pain and other neurological signs.

Control

Control via animal

Quarantine for rabbits

  • Lagomorphs can be imported into the UK from another EU country without undergoing quarantine provided that they can meet the following conditions:
    • They do not come from, nor have been, in contact with animals that have come from a holding on which rabies is present or suspected to have been present in the last month.
    • They come from a holding on which there are no signs of myxomatosis   Myxomatosis  .
    • They were born in a registered holding and kept there in captivity since birth.
    • They have a certificate based on Balai (  www.defra.gov.uk/ahvla-en/imports-exports/balai-directive/ ), Annex E part 1 from an official veterinarian, supplemented by a Declaration covering the first and second bullet points above.
  • If these conditions cannot be met, or that are coming from a country outwith the EU, they must undergo 6 months quarantine.

Print off the Owner Factsheet Traveling with your Rabbit   Travelling with your rabbit   to give to your clients.

Control via environment

  • Vaccine-containing baits have been shown to be effective in controlling rabies in foxes in areas of Europe, also in wildlife in USA.
  • Pet rabbits should be protected from contact with wildlife in areas where rabies is present.

Vaccination

  • Vaccination of mammalian pets in countries where rabies is endemic.
  • Vaccination of rabbits is not generally undertaken.

In the UK permission is needed from Ministry prior to administration of rabies vaccine and a specific reason is needed for its use.

  • Oral immunization of wildlife in some European countries has been successful.
  • New regulations to be put in place in the USA will require blood-testing, vaccination and identification of animals imported from certain countries.
  • Such vaccination must take place at least 3 months of age, using inactivated and adjuvanted rabies vaccine.
  • Vaccination must be boosted at least annually.
  • Success of vaccination will be checked using a blood test; animals must show a rabies antibody titer of at least 0.5 IU/ml.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Johnson N, Cunningham A F & Fooks A R (2010) The immune response to rabies virus infection and vaccination. Vaccine 28 (23), 3896-3901 PubMed.
  • Baer G M (1997) Evaluation of an animal rabies vaccine by use of two types of potency tests. Am J Vet Res 58 (8), 837-840 PubMed.
  • Delgado S & Cármenes P (1997) Immune response following a vaccination campaign against rabies in dogs from northwestern Spain. Prev Vet Med 31 (3-4), 257-261 PubMed.
  • Fu Z F (1997) Rabies and rabies research - past, present and future. Vaccine 15, S20-4 PubMed.
  • Tepsumethanon V, Lumlertdacha B, Mitmoonpitak C et al (1997) Fluorescent antibody test for rabies: prospective study of 8,987 brains. Clin Infec Dis 25 (6), 1459-1461 PubMed.
  • Grattan-Smith, O'Regan W J, Ellis P S et al (1992) Rabies. A second Australian case, with a long incubation period. Med J Aust 156 (9), 651-654 PubMed.
  • Faoagali J L, De Buse P, Strutton G M et al (1988) A case of rabies. Med J Aust 149 (11-12), 702-707 PubMed.

Other sources of information


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