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Rabies

Rabies causes 60,000 deaths worldwide, half of which are in India. Countries completely free of rabies include: Australia, New Zealand, Japan, Honk Kong, Singapore, Great Britain, and some

Scandinavian countries. The virus Rhabdoviridae Lyssavirus causes rabies. All mammals are capable of transmitting disease to other animals or people. 99% are from dogs.

Animal commonly carrying rabies:
1.
Dogs: Major vector of rabies especially in Asia, Latin America, and Africa.
2. Foxes: Europe, Arctic, and North America.
3. Raccoons: Eastern USA.
4. Skunks: Mid Western USA and Western Canada
5. Mongooses: Yellow mongoose in Asia and Africa, Indian mongoose in Caribbean Island.
6. Coyotes: Asia, Africa, and North America.
7. Bats: Vampire bats from Northern Mexico to Argentina. Insectiverous bats in Northern America and Europe. Man to man transmission is possible (3 cases) but precautions for medical or paramedical personnel receiving routine vaccination is not needed.

Infections with rabies occur when the virus is first inoculated into the victim and then absorbed into a susceptible cell where it multiplies. The virus then enters nerve endings. The virus will migrate to the brain and once the virus has then entered the brain, rabies symptoms begin to occur. Rabies is almost universally fatal afterwards. The term rabies refers only to when the person has the fatal condition.

The average incubation time before the development of symptoms is 90 days, although is has occurred is as little as 7-10 days to greater than a year. Rarely only a few days resulted in rabies and 1 case was over 6 years.

Children tend to develop symptoms faster because bites are closer to the brain (the virus have less to travel towards the brain), and often more severe.

Symptoms of rabies in people are divided into 2 types - encephalitic (furious) and paralytic (dumb).

Early symptoms may be vague and non-specific (fever, upset stomach), local symptoms may occur at bite site (burning, numbness, tingling or itching).

Characteristics of encephalitic (furious) rabies:

1. Fluctuating consciousness from agitation to depression, which will gradually progress to coma.
2. Phobic spasms - aerophobia and hydrophobia, (the fear of water and air).
3. Signs of autonomic dysfunction like fixed dilated pupils, increased salivation, excessive sweating and priapism.

Rabies is 100% fatal although four people to date have survived but all with neurological damage.

PREVENTION AND TREATMENT OF RABIES
Pre-exposure vaccination is giving the rabies vaccine to people who might be exposed to rabies.

The vaccine is given in three doses with a booster at 1 year and every 5 years after. It eliminates the need for post exposure immunoglobulin treatment after a rabid bite, which may not even be available in certain countries.

It also simplifies post exposure treatment to only 2 vaccine doses after being bitten.
People who should be vaccinated include researchers working with rabies, veterinarians, and remote travelers. Spulunkers may also be at risk of rabies from bats. Children of long-term travelers might also be at high risk of rabies in developing countries.

POST BIT TREATMENT

Cleaning bites is the most important step in preventing rabies. This should be done as soon as possible, first by flushing the wound with soap and water, followed by 70% alcohol, or tincture of iodine.

Rabies exposure is graded as:Type of Contact - Recommended Treatment

1. Touching, feeding, or licks, (animal)on intact skin - No treatment necessary.
2. Nibbling of uncovered skin, minor scratches or abrasions without bleeding, licks on broken skin. - Give vaccine. Stop treatment if animal observed to be healthy after 10 days in quarantine or lab tests are negative
3. Single or multiple bites Or scratches.Contaminated mucous membrane by saliva (Licks). - Give vaccine and rabies immunoglobulin. May stop treatment if rabies tests result come up negative for the animal.

After a rabid bite the rabies vaccine is usually given on days 0, 3, 7, 21, and 28. The vaccine is given in the deltoid (or thigh in children). It is not to be given in the gluteal muscle because there is poor absorption of the vaccine when given in the gluteal area.

Sometimes a double dose of the vaccine is given on day 0 if the patient is immune deficient or had a very bad bite. If a person who had been previously vaccinated within 5 years is bitten they only require 2 booster doses at days 0, 3 but do not need rabies immunoglobulin.

Rabies immunoglobulin is given to those people with severe bite(s) who have no prior antibodies that will bind to the virus to prevent them from entering the nerve tissue and spreading to the brain.

This should be given as soon as possible after being bitten since rabies has developed a few days after being bitten.

People will begin to produce their own antibodies 7-10 days after being vaccinated.

The immunoglobulin should be injected into the wound with a separate syringe from the rabies vaccine. Treatment should not be withheld while waiting tests or quarantined animals.

Intradermal injection of vaccine for post rabies exposure is done in some developing countries, which is much cheaper since less vaccine is given intradermally.

The vaccine is given in day 0,3, and 7 in double doses; and days 28 and 90 at single doses.

Some North American centers will give intradermal injections for pre-exposure since this is likewise cheaper. However when doing this these patients have to be followed closely by lab tests to confirm the effectiveness of this type of immunization with extra injections if a low immunoglobins titre is found.

Rabies links
CDC Rabies http://www.cdc.gov/ncidod/dvrd/rabies/

Aventis Pasteur http://www.rabies.com/