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− | *Vesicular stomatitis in [[Viral skin infections - Pathology#Other viruses|skin lesions]] | + | =Introduction= |
| + | 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 insures 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 |
| + | |
| + | =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: |
| + | |
| + | =Epidemiology= |
| + | *Rabies is found worldwide, though currently considered exotic to the UK |
| + | *The current position of DEFRA holds bat lyssaviruses to be present in the UK |
| + | *Rabies is a '''NOTIFIABLE''' zoonosis |
| + | *Human infection and death an occur after infection with bat rabies |
| + | |
| + | =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 |
| + | |
| + | =Rhabdoviridae by Species= |
| + | Host Range: |
| + | *All mammals are susceptible |
| + | **Very susceptible: foxes, jackals, wolves |
| + | **Susceptible (10,000x virus necessary to infect): cats, rodents, bats, skunks, cattle, mongooses |
| + | **Moderately susceptible (100,000x virus necessary to infect): dogs, sheep, goats, horses, primates |
| + | *Isolates can show to some species specificity in their reservoir host |
| + | |
| + | =Rabies Control= |
| + | *Antigenicity allows a single antigenic type to vaccinate |