Dr. Md. Salequr Rahman
Dep. Of Community
Acute highly fatal viral disease
of central nervous
system, caused by Lyssavirus
Primarily a zoonotic disease of
warm blooded animals
(Dogs, cats, jackals and wolves).
Transmitted to man by bites or
licks of rabid animals
Classical hydrophobia is clinically characterized by
a long and variable incubation period, a short
period of illness due to encephalomyelitis ending
in death, despite intensive care.
Only communicable disease that is always fatal.
35,000-40,000 human deaths occur in SEAR
countries. Bangladesh and India belong to the high
Agent: Lyssavirus type 1- it
is a bullet shaped
neurotropic RNA containing
virus. It is a large virus.
The virus is excreted in the
saliva of rabid animals. The
virus available from
naturally occurring cases
Street Virus”. Incubation period is 20-60 days in
dogs. Introduction of street virus into rabbit
modifies the virus as its incubation period is
reduced to 4-6 days. Virus isolated at this stage is
called a “Fixed Virus”. This is used for preparation
of vaccine. The intracytoplasmic inclusion bodies
named as “Negri bodies” represnt a colony of virus
particles within the nerve cell. Negri bodies contain
infectious agent. Fixed virus does not produce
Urban rabies: Infection from wild life to domestic
dogs, responsible for 99% of human cases. A single
rabid dog is capable of biting large number of
human, animals and may involve an area of 40 km.
Cats may be a source.
Wild life rabies: Sylvatic form. In jackal, fox, hyena
and other life carriers.
Bat rabies: Vampire bat is an important host and
vector of rabies (in Latin American countries)
Source of infection: Saliva of rabid animals.
Host factors: Laboratory staff, veterinarians,
dog handlers, hunters, field naturalists.
Licks on abraded skin and mucosa
Person to person: rare.
The rabies virus can infect all
Mammals are warm-blooded
animals that have hair and
mammary glands to produce
milk for their babies.
Animals like frogs, birds, and
snakes do not get rabies.
3-8 weeks; vary from 4 days to many years.
IP tends to be shorter in severe exposures
and bites on face, head and upper extremities
and bites by wild animals.
Virus replicates in muscles and connective tissues
at or near the site of introduction before it attaches
to nerve endings and enters peripheral nerves.
Spreads from site of infection centripetally via the
peripheral nerves towards the CNS; then
centrifugally in peripheral nerves to many tissues
including skeletal and myocardial muscles, adrenal
glands and skin.
Prodromal symptoms: Headache, malaise, sore
throat and slight fever lasting for 3-4 days.
Complains of pain and tingling at the site of bite.
This stage is followed by widespread excitation and
stimulation of all parts of nervous systemsensory, motor, sympathetic and mental.
The patient is intolerant to light, noise or cold
draught of air. Aerophobia may be present and
On examination: increased reflexes and
muscle spasm along with dilatation of pupils
and increased perspiration, salivation and
Mental changes include-fear of
death, anger, irritability and depression.
The symptoms are progressively aggravated and all
attempts of swallowing liquid become
unsuccessful. At later stage the mere sight/sound
of water may provoke spasm of muscles of
deglutition. The characteristic symptom of
hydrophobia is pathognomic of rabies.
Duration of illness 2-3 days. Only three people are
on record who survived.
Fixed virus grown in neural tissues of rabbits,
ships, goats, mice, rats, in embryonated duck
eggs, cell cultures.
Cell culture vaccine
1. HDC vaccine
2. 2nd generation tissue culture
Nervous tissue vaccine:
14 injections (5 ml each) are given deep s/c
around the umbilicus for 14 days.
S/E: Ascending type of paralysis and post
Propagating the rabies fixed virus in human
diploid fibroblast cells. Generally safe and
highly potent. I/M injection of 5 doses of 1
ml in deltoid region; first as soon as the bite;
other doses on 3, 7, 14, 28 days and booster
dose on 90th days.
Intradermal vaccine schedule (WHO): (0.1 ml)
2 in 2
2 in 2
2 in 2
2 in 2
Intramuscular Vaccination schedule:( 0.5-1 ml)
2 in 2 arms
one in one
one in one
Post exposure prophylaxis
Pre exposure prophylaxis
Post exposure Rx of persons who have been
1. General consideration: The aim is to neutralize the
inoculated virus before it can enter the nervous
system. Every exposure should be treated as medical
emergency. It is established that irrespective of the
class of wound, the combined administration of a
single dose of anti rabies serum with a course of
vaccine, together with local treatment of wound is
the best specific prophylactic treatment after
exposure of man to rabies.
Cleansing-immediate flushing and washing the
wounds, scratches and the adjoining areas with
soap and detergent and water, preferably under a
running tap, for at least 5 minutes. Then cleansing
with alcohol or povidone iodine. Local wound
treatment can reduce the chances of developing
rabies up to 80%.
Anti rabies serum locally
Antibiotics and anti tetanus measures
If the animal has signs of rabies and dies within 10
days of observation
If the biting animal cannot be traced.
Lab. test (florescent rabies antibody or test for
negri bodies) of the biting animal are positive for
Category 1: touching /feeding animals, lick
on intact skin( no exposure) [No prophylaxis
Category 2: Nibbling of uncovered
skin, minor scratches/ abrasions without
bleeding [immediate vaccination]
Category 3: Single/multiple trans dermal
bites/ scratches, contamination of mucus
membrane with saliva from licks, licks on
broken skin, exposure to bats[immediate
vaccination+ administration of rabies