Show Summary Details
Page of

Rhabdoviruses: rabies and rabies-related lyssaviruses 

Rhabdoviruses: rabies and rabies-related lyssaviruses

Chapter:
Rhabdoviruses: rabies and rabies-related lyssaviruses
Author(s):

M.J. Warrell

and David A. Warrell

DOI:
10.1093/med/9780199204854.003.070510_update_001

Update:

Epidemiology—increasing concern about transmission by bats.

Treatment of rabies encephalitis—new recommendations.

Pre- and postexposure prophylaxis—revised vaccine regimens.

Updated on 31 May 2012. The previous version of this content can be found here.
Page of

PRINTED FROM OXFORD MEDICINE ONLINE (www.oxfordmedicine.com). © Oxford University Press, 2015. All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Medicine Online for personal use (for details see Privacy Policy).

date: 23 April 2017

The Rhabdoviridae are a large family of RNA viruses, two genera of which infect animals: the genus Lyssavirus contains rabies and rabies-related viruses that cause at least 55 000 deaths annually in Asia and Africa.

Transmission and epidemiology

The risks and problems posed by rabies and other lyssaviruses vary across the world. Virus can penetrate broken skin and intact mucosae. Humans are usually infected when virus-laden saliva is inoculated through the skin by the bite of a rabid animal, usually a dog. Although the greatest threat to man is the persistent cycle of infection in stray dogs, several other terrestrial mammal species are reservoirs of infection. In the Americas, bat viruses are also classic genotype 1 rabies and insectivorous bats have become the principal vectors of infection to humans in the United States of America. Elsewhere in the world, there is increasing evidence of widespread rabies-related lyssavirus infection of bats. Unrecognized infection of organ donors has proved fatal to transplant recipients.

Clinical features

After a highly variable incubation period (usually 20 to 90 days), prodromal symptoms include itching at the site of the healed bite wound. These are followed by symptoms of either furious or paralytic rabies, reflecting whether infection of the brain or spinal cord predominates.

Furious rabies—the diagnostic symptom is hydrophobia, a combination of inspiratory muscle spasms, with or without painful laryngopharyngeal spasms, associated with terror, initially provoked by attempts to drink water. Patients may suffer generalized arousal, during which they become wild, hallucinated, fugitive, and rarely aggressive.

Paralytic rabies—flaccid ascending paralysis develops, starting in the bitten limb.

Diagnosis

The diagnosis can be made during life using rapid laboratory methods such as immunofluorescence of brain or punch biopsy specimens of skin taken from a hairy area. The polymerase chain reaction is used increasingly to detect rabies in saliva and skin biopsy material. However, lack of facilities hampers the confirmation of disease in developing countries where the diagnosis usually relies on recognition of hydrophobic spasms and other clinical features of furious rabies. Paralytic disease is rarely identified. Rabies has been misdiagnosed as cerebral malaria, or even drug abuse.

Management and prognosis

The few human survivors of rabies encephalomyelitis had received vaccine and, with one exception were left with severe neurological sequelae. Recently an unvaccinated patient bitten by a bat in North America made a good recovery. However, dog rabies virus infection remains universally fatal in man. Patients with furious rabies rarely live more than one week without intensive care but survival can be up to one month with paralytic disease. The mechanism of neuronal dysfunction remains elusive, and no treatment has proved effective experimentally.

Management—intensive care treatment may be appropriate for patients infected by a bat in the Americas if they present early and are already seropositive. Other patients with rabies should be sedated heavily and given adequate analgesia to relieve their pain and terror.

Prevention

Highly effective methods for control and prevention of rabies are available.

Control of rabies in domestic dogs—99% of human rabies deaths could be prevented by controlling the transmission of dog rabies, but education and resources are lacking.

Pre-exposure prophylaxis—a three-dose course of rabies vaccine is recommended for travellers and indigenous people in dog-rabies endemic areas, but the cost is often prohibitive.

Postexposure prophylaxis—at the time of a bite, correct cleaning of the wound and optimum postexposure immunization virtually eliminate the risk of rabies. Effective prophylaxis demands urgent wound cleaning with copious amounts of soap and water, followed by vaccine and rabies immunoglobulin. A new improved economical 4-site intradermal postexposure vaccine regimen could increase the availability of affordable treatment in developing countries.

Access to the complete content on Oxford Medicine Online requires a subscription or purchase. Public users are able to search the site and view the abstracts for each book and chapter without a subscription.

Please subscribe or login to access full text content.

If you have purchased a print title that contains an access token, please see the token for information about how to register your code.

For questions on access or troubleshooting, please check our FAQs, and if you can't find the answer there, please contact us.