ByJini P. Abraham

Clinical picture and Diagnosis

of Rabies

CONTENTS Hydrophobia Rabies in dogs Laboratory Diagnosis Prevention and Control

WHO’S AT RISK?? People most at risk live in rural areas where

human vaccines and immunoglobulin are not readily available or accessible.

Although all age groups are susceptible, rabies is most common in children aged under 15.

On average 40 % of post-exposure prophylaxis regimens are given to children aged 5–14 years, and the majority are male.

Anyone in frequent or increased danger of exposure to rabies virus – either by nature of their residence or occupation – is also at risk.

Travellers with extensive outdoor exposure in rural, high-risk areas

HYDROPHOBIA 80% - 90% cases Prodormal symptoms – headache,

malaise, sore throat, slight fever CNS affected – sensory, motor,

sympathetic and mental systems Stage of paralysis Duration of illness – 2 to 3 days

(exceptional cases – 5 to 6 days)

DIAGNOSIS Basis of history of bite by a rabid

animal Characteristic signs and symptoms Confirmed in patients by antigen

detection using immunoflorescence of skin biopsy and virus isolation from saliva and from other secretions.

NO TREATMENT Isolation in a quiet room Relieve anxiety and pain by sedatives Spastic muscle contractions Rehydration and osmotic diuresis Respiratory and cardiac support Medical attendants – Warned against

possible risk of contamination Pre – exposure prophylaxis immunization

MANAGEMENT

Post – exposure prophylaxis Pre – exposure prophylaxis Post – exposure treatment of persons

who have been vaccinated previously

PREVENTION OF HUMAN RABIES

Persons bitten by a suspected rabid animal To neutralize the inoculated virus before it

enters the nervous system Combined administration of a single dose of

antirabies serum with a course of vaccine, together with local treatment of wound

2 components – Local treatment of wound Immunization

POST – EXPOSURE PROPHYLAXIS

Aim – Elimination of virus from the wound Prevent infection of the nerve endings

Measures – Cleansing Chemical treatment – Virucidal agents like

alcohol (400 – 700ml/ litre), tincture, 0.01% aq solution of iodine

Suturing – 24 to 48 hours later Anti – rabies serum Antibiotics and anti – tetanus measure

WOUND TREATMENT

Observe the animal for 10 days Change of behaviour Running amuck Excessive salivation Change in the tone of bark Death of animal

If animal shows symptoms of rabies, it should be humanely killed and sent to laboratory for rabies examination

Category

Type of contact with a suspect or

confirmed rabid domestic or wild animal, or animal unavailable for

testing

Type of exposur

e

Recommended post – exposure prophylaxis

I Touching or feeding of animalsLicks on intact skin

None None, if reliable case history is available

II Nibbling of uncovered skinMinor scratches or abrasions without bleeding

Minor Administer vaccine immediatelyStop treatment if animal is healthy throughout an observation period of 10 days or if animal is proven to be negative of rabies by a reliable laboratory, using appropriate diagnostic techniques

III Single or multiple transdermal bites or scratches, licks on broken skinContamination of mucous membrane with saliva

Severe Administer rabies immunoglobulin and vaccine immediately. Stop treatment if animal remains healthy throughout an observation period of 10 days, or if animal is found to be negative for rabies by a reliable laboratory using appropriate diagnostic techniques

PRE – EXPOSURE PROPHYLAXIS Persons who runs a high risk of repeated

exposures – Laboratory staff working with rabies virus Veterinarians Animal handlers Wildlife officers

Dose of cell – culture vaccine, given either as 1ml im or 0.1ml id on days 0, 7 and 28

Booster injections administered at intervals of 2 years as long as exposed person remains at risk

POST – EXPOSURE TREATMENT OF PERSONS WHO HAVE BEEN VACCINATED PREVIOUSLY

Three 1ml intramuscular doses of HDC vaccine are recommended on days 0, 3, 7

If bite is not severe, 2 doses are needed (days 0 to 3)

RABIES IN DOGS Incubation period – 3 to 8 weeks Clinical picture –

Furious rabies Dumb rabies

FURIOUS RABIES 80% – 90% of cases Early prodormal stage Later changes –

Change in behaviour – Cardinal sign Running amuck Change in voice Excessive salivation Paralytic stage Death

Mortality rate – 100%

DUMB RABIES 10% - 20% of cases Opposite to those of furious rabies Excitative or irritative stage is lacking Predominantly paralytic Lapse into stage of sleepiness Dies in 3 days

LABORATORY DIAGNOSIS Head of animal is cut off and sent to nearest

laboratory, duly packed in ice in an air – tight container

Brain may be removed with anti - septic precautions and sent in 50% glycerol – saline for examination

Laboratory examination – Fluorescent Antibody test Microscopic Examination Mouse Inoculation test Corneal Test

CONTROL OF URBAN RABIES

Elimination of stray and ownerless dogs, combined with programme of swift mass immunization

Others methods – Registration and licensing of all domestic

dogs Restraint of dogs in public places Immediate destruction of dogs and cats

bitten by rabid animals Health education of people regarding the

care of dogs and prevention of rabies

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