Rhabdoviridae family is comprised of viruses generally known as rhabdoviruses. Rhabdoviruses have a ss(-)RNA genome and they measure between 45-100 nm in diameter. They are enveloped viruses and rhabdoviruses replicate in the cytoplasm of their host cell. They are released from their host cell by a budding process through the cytoplasmic membrane. Rhabdoviruses have a helical nucleocapsid. Viruses in the Rhabdoviridae family infect humans, animals, fish, insects and even plants. There are six genera of viruses that make up the Rhabdoviridae family, and these are: Vesiculovirus, Lyssavirus, Ephemerovirus, Novirhabdovirus, Cytorhabdovirus and Nucleorhabdovirus. Only the Vesiculovirus and Lyssavirus contain important human viruses. Vesicular stomatitis virus (VSV) and rabies virus which are found in the Vesiculovirus and Lyssavirus genera respectively are of importance to man because they cause significant human disease.
VSV causes an asymptomatic herpes-like disease in humans especially those in close contact with animals such as horses, pigs and cattle that are naturally infected by the agent. And VSV is mostly endemic in South American countries. Rabies is an acute and fatal, zoonotic viral infection of the CNS of humans. And the disease which is prevalent worldwide occurs in both animals and humans. Human infection with rabies virus occurs following the bite of a rabid dog or other animals such as wolves, foxes, jackals, bats and monkeys. The virus is present in the saliva of rabid animals and it is passed on or transmitted to humans by the bite of the animal and even when they lick an open wound on the body. Rabies virus is destroyed by UV radiation, heat, ether treatment and trypsin treatment.
Rabies virus multiplies in the connective tissues or muscle cells at the site of bite; and the virus is transported to peripheral nerves of the CNS from where neurological dysfunction occurs. Sore throat, headache, lack of appetite, malaise and fever are other mild symptoms of rabies. The incubation period of the disease is 1-3 days after exposure but it can last for weeks and even months and years depending on the intensity and site of bite. Localized paralysis, jerky movements, increased muscle tone and hydrophobia (the fear of water) are the most significant clinical syndromes of the rabies disease; and infected patients may due within weeks after infection especially when appropriate medical intervention is delayed. Human-to-human transmission of rabies virus is not possible. No treatment exists for rabies virus infection once the virus has invaded the body and symptoms starts to appear. However, supportive therapy is administered to infected individuals in order to save their lives. And rabies vaccine exists as a prophylactic measure in susceptible human population.
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