RABIES

Rabies is an infectious viral disease which is transmitted by the saliva of a rabid animal. It is characterized by nervous signs, paralysis and fatal termination.
Geographical distribution
It does not occur in Britain and Australia although it is widespread. All species of animals are prone to rabies. There is high occurrence in continental Europe as foxes are increasing in number. Cattle seem to be less susceptible than dogs and cats. It is not a serious disease in farm animals.
Etiology
It is caused by rhabdovirus. It appears to be only one strain of the virus. Isolates from different parts of the world are identical serologically but their pathogenicity differs. Bats seem to be the only symptomless carriers. Recently, a number of other viruses have been isolated. Not much is known about these viruses.
Clinical signs
Cattle are mostly affected. In Nigeria, dogs have most access to cattle. Incubation period is 2 weeks to 6 months but usually 3-4 weeks. In dogs, two distinct types are dumb rabies causing paralysis and strict rabies causing incordination may show straining/tenesmus, drooling saliva, bellows, recumbent and paralysis.
In bulls, there is increased sexual excitement. Affected animal may be hyperaestatic, charging people and objects. Bulls become sexually excited and can mount on anything. These signs occur for about 24-48 hours and the animal collapses and dies.
In sheep, the picture is similar in individual animal. In Europe, 2 or 3 animals may be affected.
Diagnosis
Diagnosis is not easy but important in human point of view. Demonstration of negri bodies in the brain is positive for this disease. Occasionally, these are not seen.
Inoculation of mouse is done and waited for 21 days.
Recently, fluorescent antibody technique has been used with fluorescent microscope. It is the best method because it is quick to perform. Take the head of the suspect to the laboratory in ice quickly. If the head is divided into two halves, the first half is put in 10% formalin and the second half is put in 20% glycine saline.
Treatment
There is no treatment for this disease.
Control
The animals should be vaccinated annually.
Stop them being exposed to the virus.
Destroy all wild fauna.
Vaccine used is passed in duck embryo. Vaccine protects for about 6 months and young dogs at about 4 months of age; after that, vaccinate annually.
Other rhabdoviruses are isolated from trade cattle in Nigeria.
208 viruses were isolated from 2179 samples.