Rabies disease its incubation, clinical symptoms, animal reservoirs, diagnosis , prevention, treatment, rabies vaccine.

 3.RABIES

Rabies is a potentially fatal viral disease that affects the central nervous system. It is an animal infectious disease caused by a bullet-shaped, enveloped RNA virus measuring 180 x 75 nm. Man is occasionally infected, and once the infection has spread to the central nervous system, the outcome is almost always fatal.

Rabies is typically transmitted through the saliva of infected animals, most commonly a rabid dog that comes into contact with blood through a bite. The virus spreads from muscles to peripheral nerves to the spinal cord and brain once infected. The illness progresses from flu-like symptoms to convulsions, hallucinations, paralysis, or breathing failure, and almost always to death. The risk of infection is determined by the severity of the bite. Typically, the disease does not spread from person to person.

Incubation

The virus enters small nerve endings at the site of the bite after inoculation. The virus slowly travels up the nerve to the central nervous system, where it replicates, and then down the nerves to the salivary glands, where it replicates again. The length of the nerves determines how long this takes. A bite to the foot will take much longer to develop than a bite to the face. Incubation can last anywhere from two weeks to six months. The primary wound is frequently healed and forgotten by the time clinical symptoms appear.

Clinical Symptoms

• Furious Rabies

                          When a virus enters the central nervous system, the patient experiences headaches, fever, irritability, restlessness, and anxiety. This could lead to muscle pains, salivation, and vomiting. After a few days to a week, the patient may go through a stage of excitement and painful muscle spasms, which can be triggered by swallowing saliva or water. As a result, they fear water (Hydrophobia). Patients are also overly sensitive to air blown in their faces. The patient is only excited for a few days before slipping into a coma and dying.

Once clinical disease manifests, it progresses rapidly and inexorably to death, despite all treatment. Fever, headache, malaise, insomnia, anxiety and confusion, slight or partial paralysis, excitation, hallucinations, agitation, salivation, difficulty swallowing, convulsions, and fear of water (hydrophobia) due to swallowing difficulty

• Dumb Rabies

                        Starts the same way, but instead of progressing into excitement, the subject retreats steadily and quietly downhill to death, with some paralysis. Rabies diagnosis can be easily missed.

• Animal Rabies

                                It closely resembles human rabies. Without provocation, the animal may bite vigorously and viciously at anything: sticks, stones, grass, other animals, and humans. Be cautious of approaching or picking up wild animals that appear abnormally tame or sick.  

A rabid animal carries the virus in its saliva, so if it bites a person, the virus enters the person's body. It is also possible to contract rabies from an animal scratch. Animals with rabies are sometimes described as "foaming at the mouth," which occurs because the animal's nerves no longer function properly and it can't swallow its own saliva.

Disease Transmission

Rabies is most commonly transmitted through the bite of a rabid animal. People are rarely infected with rabies when infected animal saliva comes into contact with their eyes, nose, mouth, or a wound. This could happen if you get licked by an infected animal. Another possible route of rabies virus exposure is inhalation, which is likely to affect only laboratory workers.

The disease is endemic in most parts of the world's wild animals, though some countries (including the United Kingdom and Australia) have achieved rabies-free status through aggressive control measures and campaigns. The natural reservoir is the wild animal cycle. Domestic animals (cattle, horses, pigs, dogs, and cats) can be bitten and infected by wild animals, who can then infect humans. On rare occasions, wild animals may directly infect humans. In recent decades, a distinct strain of dog rabies has been identified as spreading from West Africa eastwards and southwards in Africa and Asia.

You are most likely to contract rabies if your activities expose you to the rabies virus or potentially rabid mammals. Veterinarians, animal caretakers, laboratory workers, hunters, forest rangers, and visitors to bat-inhabited caves are all at risk.

   Animal Reservoirs           

    Mongoose (the main wild reservoir in RSA), jackals, bats (some evidence suggests carrier status and droplet infection), foxes (in Europe), skunks, raccoons (in the United States), and semi-wild dogs      

Diagnosis

Certain information may help your doctor determine your risk of contracting rabies and how to treat you if you've been bitten or had contact with an animal that may have rabies. Keep the following in mind:

A description of the animal and the vaccination status of the domesticated animal should be obtained from the location of the incident. If the animal can be safely captured and tested for rabies, it will not be rabid if it survives for 8 days. Another option is for veterinarians to run tests on the animal's brain tissue to see if it has rabies. Testing is possible quickly, but only after the animal has died.

If you have rabies symptoms, a series of tests involving blood, saliva, spinal fluid, brain tissue, or skin tissue taken from the nape of your neck may be required to identify or rule out rabies infection.

Prevention

To help prevent rabies exposure, keep your pets and other domesticated animals up to date on animal rabies shots. Contact with wild or unfamiliar animals, whether alive or dead, should be avoided. Seal or close any openings through which animals could enter your home. Report stray animals, as well as those that act strangely or are sick, to your local animal control authorities. Teach your children never to handle strange animals. Consider getting a rabies vaccine if your job or activities may expose you to the rabies virus or a potentially rabid mammal. This vaccination, known as pre-exposure prophylaxis, consists of three injections spread out over three or four weeks. A booster shot can keep the vaccination effective.

Treatment

If you have been bitten by a rabid animal, thoroughly wash the wound or area of exposure with soap and water. It is critical to act quickly. Death almost always follows the appearance of the first signs and symptoms. Contacting a doctor as soon as possible after a potential rabies exposure greatly increases the chances of survival.

The treatment, known as post-exposure prophylaxis, consists of one dose of rabies immunoglobulin and five doses of rabies vaccine administered over the course of 28 days. Rabies immunoglobulin and the first dose of rabies vaccine are given to the patient as soon as possible after exposure. Immunoglobulin is injected around the bite site and into the upper arm muscle.

Immunoglobulin's are proteins that fight disease by providing you with temporary antibodies. The rabies vaccine stimulates the body's production of its own antibodies. Antibody production takes time, but antibodies produced by the body are more effective than those found in rabies immune globulin.

Although the vaccine is not painful, mild physical reactions may occur. Keep an eye out for reactions like swelling or redness where the injection was given. Other possible side effects include headache, fever, nausea, muscle aches, and dizziness. If side effects cause you discomfort, consult your doctor.

Rabies Vaccine

For safe human use, a good but expensive killed virus vaccine (Human Diploid Cell Vaccine, HDCV) grown in human fibroblasts is available. The virus's unusually long incubation period allows for the effective use of active immunization with vaccine after exposure. When used, the vaccine has significantly reduced rabies deaths. (Older killed virus vaccines derived from infected neural tissues were poorly immunogenic and caused allergic encephalitic side effects, but they are still used in developing countries.

Prophylaxis

High-risk individuals, such as veterinarians, may be immunized before exposure and require only one or two booster doses if exposed to rabies.

Animal vaccine

For domestic animals, a variety of live and killed virus vaccines are available (farm animals, cats and dogs).

4th disease

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