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| You are in>Health channels>Diseases>Rabies |
| Rabies |
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| Introduction |
| Rabies is a viral infection affecting the nervous
system of animals. It can be transmitted to humans by a bite or the exposure of broken
skin of the humans to that of the infected animal’s saliva. It is caused by Rhabd
Virus. The name Rabies comes from the Latin word, rabidus meaning mad, derived from the
Sanskrit root rabhas, which means violence.
The disease in humans is also called hydrophobia because of the patient's fear of
water.
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| Transmission |
| Rabies is transmitted by virus-laden saliva that
enters the body by the bite of an infected animal. Rarely, the infection can also occur
following non-bite exposures such as licks or aerosols. The virus travels from the wound
along the nerve pathways to the brain where it causes inflammation that results in the
symptoms of the disease. The incubation period (the period between the time of the
entrance of the virus and the development of the symptoms of the disease) ranges from 10
days to 3 years, with the average period of 3 to 7 weeks. Dogs, bats, skunks, racoons,
foxes, and other animals are other sources of rabies virus. There are an estimated 25,000
(actual figure may be 50,000) deaths due to rabies in India each year, and about 3 million
people receive the vaccine for prevention of rabies following a bite by a suspected rabid
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| Rabies in dogs |
| In dogs the incubation period is usually 3-6 weeks
but it may range from 10 days to a year. The initial signs are a change in the disposition
of the infected animal with restlessness, snapping at imaginary objects, licking or
gnawing at the site of the bite. After 2-3 days of this prodromal stage, the disease
develops into either furious or dumb type of rabies. In the furious type, which is more
common, the dog runs amok, biting without provocation and indiscriminately. The lower jaw
drops and saliva drools from the mouth. Paralysis, convulsions and death may follow. Dumb
rabies is a paralytic form in which the animal lies huddled, unable to feed. The dog may
not bite but attempts to feed it may be dangerous.
About 60% of the rabid dogs shed virus in the saliva and usually die within 3-5 days.
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| Symptoms: |
The course of the disease in human beings can be
classified into four stages: prodromal, acute neurological phase, coma and death.
- The onset of the disease is usually initiated by prodromal symptoms such as low-grade
fever, headache, malaise and decreased appetite (anorexia). There may also be pain,
itching or numbness and tingling at the site of the wound. Apprehension, anxiety,
agitation, irritability, nervousness, insomnia or depression characterises the prodromal
phase, which lasts for 2-4 days.
- The acute neurological phase usually begins with hyper activity, which is
characteristically intermittent with bouts of bizarre behaviour, agitation or seizures
appearing between apparently normal periods. One also experiences difficulty in swallowing
water together with intense thirst. Patient may be able to swallow dry solids. Attempt to
drink water bring about painful spasms of pharynx and larynx producing choking or gagging,
patients thus develop a dread for even the sight or sound of water which is called
Hydrophobia. Generalised convulsion follow. Death usually occurs within 1-6 days due to
respiratory arrest.
- Patients who survive the stage of acute neurological involvement lapse into coma, which
may last for hours or months. Death is due to respiratory arrest.
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| Prevention: |
Prevention depends upon enforcement of the following
public health policies:
- Vaccination of people in high risk occupations
- Regulations on importing dogs and other animals in disease free countries.
- Domestic cats and dogs should be immunised against rabies.
- Teach your children not to approach or play with wild/ undomesticated animals.
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| First aid in the case of a bite by an
animal: |
- Wash all suspect animal bites with soap and water.
- Seek medical advice immediately because preventive measures must start immediately for
it to be effective.
Prevention is by an injection of rabies immunoglobulin followed by anti rabies
vaccination. If possible the animal that inflicted the bite should be captured and
observed for 10 days. Generally the animal develops symptoms of rabies and becomes ill
within 3 days of shedding the rabies virus in their saliva. If the animal is symptom free,
the treatment can stop. Animals affected by rabies, salivate extensively and act
aggressively.
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