Management Of dog bite and rabies

4.  Rabies is an invariably lethal, acute viral dx of
the CNS that affect all mammals usually
transmitted by infected secretions.
 Transmission of rabies to humans takes place
thro’ exposure to saliva during a bite by an
infected animal.
 An effective rabies vaccine was first developed
over a century ago, making rabies a
preventable disease.

5.  Dogs are commonly used for security and as
pets by most people in Nigeria, however it is
also used for hunting and occasionally serve as
source of protein.
 Despite its usefulness, dogs can be very
harmful to humans when they are rabid.

6.  Rabies and rabies related viruses are in the
family Rabdoviridae with at least seven distinct
types, with genus lyssa-virus.
 Isolates of rabies virus from different animals
species differ in their antigenic and biologic
property.
 Rabies viruses are bullet-shaped, enveloped
single stranded RNA virus of negative polarity.

7.  An understanding of epizootiology of rabies is necc
in evaluating the risk of exposure and need for
rabies PEP in humans.
 Rabies is fd in mammals in all regions of the world
with possible exception of Antarctica.
Rabies exist in two forms:
 Urban (furious) rabies, propagated chiefly by un
immunized domestic dogs.
 Sylvatic (dumb) rabies, propagated by skunks,
raccoons, mongoose, foxes and bat.

8.  World wide incidence of rabies is estimated at
more then 30,000 cases per year.
 Southeast Asia, the Philippines, Africa and
Indian subcontinents are areas where the dx is
especially common.
 The main reservoir of rabies world wide is
domestic dogs.

9.  Increased travel of human, along with
intentional and unintentional translocation of
animals has made the recognition of clinical
rabies and its prevention of increasing
importance.
In a 12-yr retrospective study (UBTH):
 143 cases of dog bite
 1 victim of rabies.

10. A decade of experience in two hosp in Sokoto:
 16 cases of rabies.
 Over 900 victims of dog bite.
A 10 year experience in ABUTH Zaria:
 A single case of rabies
 81 cases of dog bite
 Rabies in insectivorous bat occur in UK, Europe, USA,
Canada and Africa, essentially every locality where
bats are found.

11.  The first event in rabies is the inoculation of the
virus through the skin, usually through a bite that
delivers virus laden-saliva.
 Initial viral replication appear to occur within the
striated muscle cell at the site of inoculation
 .
 Peripheral nervous system is thus exposed.
 virus then spread centripetally CNS at rate of
→
3mm/hr.

14.  Virus once in the CNS replicates almost exclusively
in the gray matter.
Incubation period of rabies is exceedingly variable
ranging from 7 days to >1 year (mean 1 to
2months) and apparently dependent on :
 amount of virus introduced
 Amount of tissue involved
 Actual distance that the virus has to travel from site
of inoculation to the CNS.

16. Rate of infection and mortality are:
 Highest from bite on the face
 Intermediate from bite on the hand and arm
 Lowest from bite on the leg.
Cases of human rabies with extended incubation
period (2 to 7 years) have been reported but
they are rare.

17.  The most characteristic pathologic finding of
rabies in the CNS is the formation of
cytoplasmic inclusion
Negri bodies.
 Negri bodies are absent in 20% of cases.

19. Clinical manifestation of rabies can be divided
into four stages:
1. Non specific prodrome
2. Acute encephalitic phase
3. Profound dysfunction of brainstem centre
4. Death or in rare cases recovery

20.  Rabies may also present as an ascending
paralysis resembling the Laundry/Guillain
Barre syndrome.
 Paralytic rabies also occur in southeast Asia
among person with canine exposure.

21.  Non specific , CBC, mild CSF pleocytosis.
 Rabies virus specific antibodies in serum and
CSF:
 Indirect fluorescent antibody test.
 Rapid fluorescent focus inhibition test
 Reverse-transcriptase PCR on fresh saliva.
 RT-PCR on skin biopsy sample.

22.  There is no specific treatment for clinical
rabies.
 Death is virtually inevitable once clinical signs
develop.
 Medical management is supportive and
palliative

24.  Bites and scratches from a potentially rabid animal
should be thoroughly washed with soap and water.
 After all soap has been removed, cleanse with
benzyl ammonium hydrochloride (Zephiram)
 Wound that have broken the skin should receive
tetanus prophylaxis.
 Bite by a seemingly healthy animal requires
surveillance.

25.  PEP should be given in cases of rabid or
suspected rabid bite or the status of
immunization is not known.
 Human rabies immune globulin (HRIG) is
injected at a dose of 20Units/kg of body wt.
 Human diploid cell vaccine (1ml) should given
on days 0 , 3, 7, 14 and 28.

26.  Is available to persons at the risk of rabies
exposure.
 The recommendation is that a series of 1ml
doses of modern cell culture vaccine
administered intramuscularly on days 0, 7 and
21or 28.
 If an exposure occurs, a previously immunized
person should receive post exposure boosters
consisting of two doses on 3 days apart.