Description of Rabies and its Spread, Clinical finding, Prevention and Control
Introduction:
Rabies is an acute viral zoonotic disease (a disease
that is transmitted to human from animal) characterized by sign of abnormal
behavior, nervous disturbance ascending paralysis and death. All warm blooded
mammals are susceptible to infection by the rabies virus. The virus is present
in the saliva of the infected animal and is transmitted to the other animal and
to human through saliva.
Causative agent:
Rabies is caused by RNA virus belongs to family Rhabdoviridae
and genus lyssavirus.
The virus is bullet shape and measure about 180-250 nm in length by 75nm in
diameter.
Spread of rabies:
· Rabies
is transmitted through direct contact between the virus (e.g. in contaminated
saliva) and mucus membrane or wound.
· Human
infection most frequently occurs following a transdermal bite or scratch from
an infected animal.
· Very
rare, rabies has been contracted by inhalation of virus containing aerosol (eg.
In caves inhabited by bats)
· Human
–human transmission has never been confirmed. With the exception of organ
transplant from rabid patient.
·
Transmission through the
consumption of milk and cooked meat has not been reported to date but the
consumption of milk and meat from rabid animal is discouraged.
Rabies exist in 2 cycle: urban and sylvatic. In
urban cycle, dog are the main reservoir where as in sylvatic cycle, wild animal
are main reservoir.
Many European countries and North America have already
eliminated rabies as a public health problem through mandatory vaccination of
dog and good access to post exposure prophylaxis for human beings.
More than 95% of human death occurs in Asia/ Africa.
And 99% of human rabies cases came from dogs. There is a small proportion of
human rabies reported due to transmission via wild life (such as fox, wolves,
jackels, raccoon, bats). Rabies kills more than 60,000 people each year (that
is one death in every 9 minute) over 150 countries. Some countries like
Australia, Switzerland, Netherland, rabies are eliminated.
WHO (world health organization)
OIE (world
organization for animal health)
FAO (food agricultural organization)
GARC (global alliance for rabies control)
|
Global Eradication of dog mediated rabies by 2030. (zero by thirty project) 0.30 How virus travels:
 Clinical findings: In dog: 1. Furious
form This
is classic “mad dog syndrome”. There is rarely evidence of paralysis during
this stage. This form can be divided into stage of melancholy and stage of
excitation.
Stage
of melancholy: In this stage, dog may show bite
inanimate or animate objects. It may show unusual violence and frenzy
behavior. Rabid dog may move from one
village to other a long distance in a circular way and thus spread the disease
over wide areas. The animal may lick water and attempt to drink but due to
obvious paralysis of pharyngeal and laryngeal muscle does not succeed to drink
water. The above period last for 1 to 3 days.
Stage
of excitement: in this form dog may become very
aggressive. Dog may hide in dark place due to photophobia. The voice may be
change due to the paralysis of vocal cord. Animal may lick their genital area
its show that the sign of heat. In the fag end, the dog will lose its ability
to bark. The lower jaw will hang, tongue will protrude and head will drop down.
The dog will develop dyspnea, ascending paralysis, coma and death. This period
may last for 1 to 7 days.
2. Dumb form: This form is also called paralytic form. In this form there is paralysis of lower jaw, tongue, larynx, and hind quarter. The dog is unable to close the mouth (open mouth condition). In fair percentage of cases, the owner is suspicious that a bone or some other object might have stuck in the neck and owner may try to open the mouth for examination and thus prone them to the possibility of contracting the infection. The entire clinical course of the disease up to the death takes 1 to 7 days. 10 day confinement
and observation period: Clinically course
usually less than 7 days animal dead before end of 10 days.
In general if a
biting dog does not die within 10 days rabies is unlikely.   In human: Initial symptoms:
pain or paraesthesia at the wound site Later:
hyperactivity, hallucination, hydrophobia, paralysis and coma and death Furious form: ·
Hydrophobia, photophobia, aerophobia ·
Excitation and confusion ·
Excessive sweating/ salivation’ ·
Dehydration and death in 2 to 5 days
Paralytic form: ·
Gradual ascending paralysis ·
Hydrophobia is not seen ·
Coma, death in 1-2 weeks
Approximately 80%
of patient present with classical (furious) rabies and 20% present with
paralytic rabies. 40 to 50% of
people who are bitten by suspected rabid animal are children under 15 years
age. In Nepal less than 100 people have been died each year due to rabies.
How long will it
take to show symptoms in human?
Generally between
1 to 3 month to more than 1 year.. But it may be short as 4 days or long or may
be many years. It depends upon location of bite and how deep the wound WHO classification
of Exposure:
Post exposure
prophylaxis (PEP):
Diagnosis: Diagnosis can only
be confirmed by laboratory test preferably conducted postmortem on CNS tissue
removed from cranium. Diagnosis
technique for rabies: 1.
Direct fluorescent antibody test (DFA) 2.
Mouse inoculation technique (MIT) 3.
Polymer chain reaction (PCR) 4.
Tissue culture infection technique (TCIT)
Can we treat after
appearance of symptoms? No treatment of
rabies after the appearance of symptoms. Fatal after symptoms begin.
Prevention and
control: ·
Rabies in human can be prevented, after
exposure by PEP. Proper wound management combine with PEP is close to 100%
effective in preventing rabies. ·
Immunize all dog and cat owned by an
individual or by the community ·
Immunize any person with proven or
probable exposure to rabies and administer rabies immunoglobulin in case of
severe exposure ·
Wild animal should not be kept as pets ·
Strict quarantine regulation ·
Human as high risk (eg. Veterinarian, vet
technician, lab person, volunteer, etc.. ) much received pre exposure
immunization. ·
Pre exposure prophylaxis : 0,7, 21 or 28
days ·
Post exposure prophylaxis:0,3,7, 14, 21
days ·
Vaccine should never be administered in
Gluteal region.
·
Rabies awareness and vaccination program     Local wound
management: ·
Through washing and flushing of the wound
for approximately 15 minutes with soap or detergent and plenty of water is
required. ·
If local irritant like herbs, oil, chilli
or turmetic powder have been applied, there should be removed by through
washing of the wound ·
After wound has been washed, local
antiseptics like Povidine iodine should be applied on the wound.
·
Whenever necessary, tetanus prophylaxis
should be administered. Dr. Manoj karki (B.V.Sc & A.H) 2020/09/28 |
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