RABIES IN ENGLISH

                                                    

                                                  RABIES IN ENGLISH

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RABIES-

           Rabies, also known as hydrophobia and acute viral encephalomyelitis is an acute, highly fatal viral disease of the central nervous  system, caused by Lyssavirus type 1. It is transmitted to man usually by bites or licks of rabid animals. It is the only communicable disease of man that is always fatal.

           Rabies is a world wide disease. It occurs in more than 150 countries and territories. Although a number of carnivorous animals  and bat species serve as natural reservoir, rabies in dogs is the source of 99 per cent of human infection, that’s why common people call it  a dog bite disease.

           CAUSATIVE AGENT-

           Rabies is caused by Rabies virus which is a rhabdovirus of the genus Lyssavirus. is a bullet shaped neurotropic RNA containing virus. Rabies virus particles contain two distinct, major antigens : a glycoprotein (G protein) antigen from the virus membrane and an internal nucleoprotein antigen. The virus is excreted in the saliva of the affected animals.

           Rabies virus replicates in muscle or connective tissue cells at or near the site of introduction before it attaches to nerve endings and enters peripheral nerves. It spreads from the site of infection  towards the central nervous system. Following infection of the central nervous system, the virus spreads  in peripheral nerves to many tissues, including skeletal and myocardial muscle, adrenal glands and skin.

           MODE OF TRANSMISSION-

           Biting of Wild and domestic animals can spread rabies. Such as dogs, foxes, coyotes, wolves and jackals; also skunks, racoons, mongooses and other biting mammals . In developing countries, dogs remain the principal reservoir. virus enters our body when a rabid animal bites, because it's saliva contains virus.

           Person-to-person transmission is theoretically possible, but rare and not well documented.

           The incubation period in man is highly variable, commonly 1-3 months following exposure but may vary from 7 days to many years. The incubation period depends on the site of the bite, severity of the bite, number of wounds, amount of virus injected, species of the biting animal, protection provided by the clothing and treatment undertaken.

           CLINICAL MENIFESTATIONS-

           The disease begins –

           headache,

           malaise,

           Sore throat and

           Slight fever lasting for 3-4 days.

           Later symptoms related to nervous system starts such as–

           patient is intolerant to noise,

           Intolerant to bright light (photophobia)

           Aerophobia (fear of air) specially cool air (fanning a current of air across the face which causes violent spasms of the pharyngeal and neck muscles)

           The symptoms are progressively aggravated.

           Swallowing liquid become unsuccessful.

           At later stage the mere sight or sound of water may provoke spasm of the muscles of deglutition. This characteristic symptom of hydrophobia (fear of water)

           The patient may die abruptly during one of the convulsions or may pass on to the stage of paralysis and coma and than die.

             

DIAGNOSTIC INVESTIGATIONS-

Ø  A clinical diagnosis of hydrophobia can be made on the basis of history of bite by a rabid animal and characteristic signs and symptoms.

Ø  Rabies can be confirmed in patients early in the illness by antigen detection using immunofluorescence of skin biopsy, and by virus isolation from saliva and other secretions.

TREATMENT-

           There is no specific treatment for rabies till date. Case management includes -

           (1) The patient should be isolated in a quiet room protected as far as possible from external stimuli such as bright light, noise or cold draughts which may precipitate spasms or convulsions

           (2) The patient should be treated with sedatives such as morphine to relieve pain and anxiety.

           (3) muscle relaxants may be given, adequate hydration is maintained and

           (4) ICU care may be needed to provide respiratory and cardiac support in severe condition

PREVENTION-

Ø  Register, license and immunize all dogs and cats in enzootic countries.

Ø  Educate pet owners and the public on the importance of restrictions for dogs and cats (e.g. pets must be leashed in congested areas when not confined on owner’s premises

Ø  Collect and immunize ownerless animals and strays and control their population.

Ø  Maintain active surveillance for rabies in animals. Laboratory capacity should be developed to perform   testing on all wild animals involved in human or domestic animal exposures

Ø  Detain and clinically observe for 10 days any healthy-appearing dog or cat known to have bitten a person. Dogs and cats showing suspicious signs of rabies should be sacrificed and tested for rabies.

Ø  In the case of bites by a normally behaving valuable pet , Individuals at high risk (e.g. veterinarians, wildlife conservation personnel and park rangers, staff of quarantine kennels, laboratory and field personnel working with rabies, long-term travellers to rabies-endemic areas) should receive pre-exposure immunization.

Ø  wild or zoo animal, it may be appropriate to consider postexposure prophylaxis for the human victim.

Ø  The aim of post-exposure prophylaxis is to neutralize the inoculated virus before it can enter the nervous system. Every instance of human exposure should be treated as a medical emergency.

Ø  First aid is very important in rabies prevention, Prompt and adequate local treatment of all bite wounds and scratches is the first requisite and is of utmost importance. The purpose of local treatment is to remove as much virus as possible from the site of inoculation before it can be absorbed on nerve endings.

Ø  Immediate flushing and washing the wound(s), scratches and the adjoining areas with plenty of soap and water, preferably under a running tap, for at least 15 minutes is very importance in the prevention of human rabies. If soap is not available, simple flushing of the wounds with plenty of water should be done as first-aid.

Ø  Whatever residual virus remains in the wound(s), after cleansing, should be inactivated by irrigation with virucidal agents such as alcohol (400-700 ml/litre), tincture or 0.01 % aqueous solution of iodine or povidone iodine.

Ø  Use of antiserum- Specific immunological protection in humans is provided by administration of human (HRIG) or equine (ERIG) rabies immune globulin at site of bite as soon as possible after exposure to neutralize the virus, and then by giving vaccine at a different site to elicit active immunity

Ø  Immunization with purified cell-culture vaccine (CCV) and embryonated egg-based vaccine (EEV) have proved to be safe and effective in preventing rabies. These vaccines are used for pre-exposure as well as post-exposure prophylaxis. 1ml dose is given at 0,7 and 21 days intramuscularly.

Ø  Reporting- Reporting of all cases to local health authority is very important to prevent and control rabies and to actively search rabid animals in the area.

Ø  Isolation: Contact isolation for respiratory secretions for duration of the illness is also of equal importance.

Ø  Disinfection – Concurrent and terminal disinfection of saliva and articles soiled ith saliva and other body fulids of patient is recommended. Although transmission from a patient to attending personnel has not been documented, immediate attendants should be warned of the potential hazard of infection from saliva, and wear rubber gloves, protective gowns, and protection to avoid exposure from a coughing patient.