Category:Rhabdoviridae
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Rhabdoviridae
Rabies is a neurological killer that has evolved a fool-proof technique of transmission, and it cleverly evades the species barrier to present a potent threat to mammalian life. While the simplicity of the virus ensures its transmission, it also contributes to its weakness: its monoclonal antigenicity means that a single vaccination covers all strains of the disease. Though rabies is considered endemic in parts of the developed and undeveloped world, vaccination schemes have rendered the disease controllable to a satisfactory degree. Nonetheless, infection is still largely fatal and the disease should not be taken lightly.
Morphology
- Large, enveloped, negative-sense RNA virus
- Bullet-shaped with short glycoprotein spikes
Types and Subtypes
Two Genera:
- Lyssaviruses: 7 genotypes
- Genotype 1 is classical rabies
- Genotypes 2-7 more limited in distribution
- Genotype 4 infects insectivorous bats
- Vesiculoviruses are all exotic to the UK:
- Vesicular Stomatitis Virus
- Ephemeral Fever
- Fish Rhabdoviruses, such as viral hemorrhagic syndrome and infectious haematopoetic necrosis virus
Virulence and Pathogenesis
- Rabies is moderately resistant: it can survive well in dark places at low temperatures for several days
- Infection occurs through a penetrating bite in which virus is transmitted via saliva
- Incubation period is variable but can be long (10 days to 12 months), and increases with distance of the bite to the CNS
- 80% show signs within 4 months
- Primary replication of the virus occurs in the muscle
- The virus gains access to nervous tissue and travels toward the brain, where it continues to replicate
- It then migrates down cranial nerves to infect salivary glands and the cornea
- Virus is shed in saliva and tears and can be shed BEFORE the onset of classical signs
- The onset of clinical signs in dogs and cats includes:
- Behavioral changes
- Pyrexia
- Salivation
- Dilation of pupils
- Two forms of the virus exist:
- Furious form:
- Common to cats and dogs
- Abnormal aggression, salivation, and attack without provocation
- Disordered wandering, "copulatory" movements.
- Incoordination, convulsions, coma and death within 3-10 days
- Dumb form
- May or may not follow Furious form
- Common to ruminants and horses
- Ruminal tympany, tenesmus, diarrhoea
- Paralysis of lower jaw, drooling saliva, tremors and progressive paralysis
- In dogs, a change in voice may be observed (bellowing)
- Furious form:
- Human infection is characterized by hydrophobia
Pages in category "Rhabdoviridae"
The following 4 pages are in this category, out of 4 total.