Rabies

From MicrobeWiki, the student-edited microbiology resource
"Rhabdoviridae" Tranmission electron microscope picture of the viruses outer envolope. From: ppdictionary.com [1]

Taxonomy

| Order = Mononegavirales | Family = Rhabdoviridae | Genus = Lyssavirus | species = Rabies Virus|

NCBI: [3] Genome: Rabies Virus [4]

Description

Rabies (derived from Latin meaning 'Madness') is a viral disease caused by Lyssavirus rabies virus. The virus is a neurotropic, capable of invasive infection the central nervous system. The disease is extremely lethal to those unfortunate enough to show symptoms of the infection. The primary transmission of the virus to humans occurs through dog bites and scratches. The numbers vary widely form country to country, however, it is estimated that 55,000 people die per year from the rabies virus in Asia and Africa . The disease can be dramatic in its appearance as with many animals the disease is known to cause hyperactivity and sporadic behavior while becoming aggressive to things around them and eventually succumbing to paralysis of muscles.

History and Impact

"middle ages rabid dog" A woodcut from the Middle Ages showing a rabid dog. From: Wikipedia.com [2]

Virology

Pathogenisis

Transmission

Infection to humans usually occurs through a bite or scratch from an infected animal. Saliva from infected animals, as well as humans, can cause rabies when in contact with mucous tissues or recent skin wounds. Inhalation of aerosols containing virus particles as well as transplant of viral infected tissues have also been documented as possible forms of transmission. Many animals have the potential to carry the virus, but the most common source is dogs. Bats are a common source in the Americas. Other animals known to carry the disease include foxes, raccoons, skunks, jackals, and mongooses. Human to human infection through bite or scratch is hypothetically possible, but has never been confirmed.

Incubation

The rabies virus has a fairly long incubation period in comparison to many other viruses. Average time from inoculation to symptoms is approximately 1-3 months, however, cases have been reported of symptoms showing in as little as 1 week, and as long as 6 years.

Epidemiology

Virulance Factors

Diagnosis

No tests are currently available prior to symptoms to test for the viruses presence. The Virus can be confirmed via intra vitam and post mortem procedures that detect the virus as a whole, the viral antigens from host production, or the nucleic acids of the virus from infected tissues. Examples of these detection methods include reverse transcription polymerase chain reaction (RT PCR) test kits, negri bodies found in neuron cells, use of florescent tagged antibodies in infected tissues, live viral culturing (including WI-38, BHK-21, or CER), and several serological tests (including MNT, RFFIT, and EIA). Some of the tests can even be combined such as using IF on live tissue cultures to test for presence of rabies antigens.

Treatment

Prevention

Rabies in animals

Dogs

Bats

Opossums

Foxes

Wolves

Other animals

Host Immune Response

References