Rabies Communicable disease

2. ILOs
By the end of this section, you should be able
to:
• Identify epidemiology and risk factors of rabies
• Understand the chain of infection of rabies
infection.
• Define various measures of prevention and
control for rabies

3. Zoonotic
Disease
Transmitted
from animals
to man.
Acute Viral
Infection
Affect the
central
nervous
system (CNS).
Identification
RABIES

4. RABIES
• Causative organism: Rhabdovirus
Infectious Agent

5. RABIES
Clinical Picture
Hydrophobia
Excitability
Paralysis
There is reflex contraction at the sight of liquids
Spasm of swallowing muscles
Alternate periods of excitability up to Mania & quietness
Paralytic manifestations are late or absent

6. RABIES
Bite infection
Viral pathway (just for illustration)

7. Rabies virus (Rhabdovirus)

8. • Diagnosis –
• Direct FAT –
demonstrate rabies
antigen in touch
impressions of brain
tissue
• Reverse transcription-
Polymerase chain
reaction RT-PCR
• Antemortem diagnosis –
humans only
• FAT, RT-PCR is
performed using a skin
biopsy, skin, corneal
impression, saliva
• Negri bodies in the
hypothalamus,
thalamus, cerebral
cortex
– Not all virus
positive brains
show Negri bodies
– Virus isolation by
intra cerebral
inoculation of mice
with fresh
homogenized
tissue.
Rabies Diagnosis

9. RABIES
Epidemiology
• Occurrence: 50,000 human deaths / year
world wide

10. RABIES
Urban type Wildlife type
Reservoirs
In Dogs and
Cats
In Wolves,
Foxes and Bats
Reservoirs

11. DR, VINOD KAUL

12. RABIES
Most
common
Respiratory
(Rare)
Theoretical
• Transmission from person to person .Has
never been documented.
Modes of Transmission
• Bite of infected animal.
•In laboratory
work
In bat caves

13. RABIES
Disease in Animals
Incubation period: from 20 to 60 days or more.
Furious rabies
The animal is
easily irritated
paralytic rabies
The animal tends to
hide and gets
paralyzed
Clinical picture depends on: The dose of the virus and its
strain

14. RABIES
10 Days
Average
6 weeks
15 months
Incubation period
•Severe Wound
•Site rich of nerve
supply
•Bites of head
&neck
•High viral load
•No protection by
clothes
•Mild wound
•Site poor in nerve
supply
•Bites distant from
head & neck
•Protected by
clothes

15. RABIES
• From dogs and cats: For 3–7 days before onset
of clinical signs and throughout illness. Bats and
skunks may shed the virus for 1–2 weeks before
onset of disease.
Period of Communicability

16. RABIES
Diagnosis and Prevention
1-History of exposure and clinical picture
2- Prompt and adequate treatment of all skin wounds
a. Cleansing with 20% soap solution.
b. The wound should not be sutured
immediately.
c. The use of antibiotics and tetanus
prophylaxis may be indicated.

17. • Pre-exposure Immunization to high risk
groups:Veterinarians, Laboratory workers with
rabies, Dog handlers, Field workers by (HDCV or
RVA vaccines should be given 3 doses. on days
0, 7 and 21 or 28. Antibody titre is periodically
examined and if it declines a booster dose of the
vaccine is given to these groups.
•

18. RABIES
3- The dog kept under supervision for 10
days for symptoms of rabies.
If symptoms developed
Brain extraction
and examination
If symptoms not
developed
If the dog escaped

19. RABIES
Active
immunization
Human Diploid
Cell Vaccine
Rabies
Vaccine
Adsorbed
Passive
immunization
Rabies immune
globulin
Post exposure prophylaxis:

20. RABIES
• 1-Semple
vaccine.
• 2- Suckling
mouse
vaccine.
• 3- Duck-
embryo
vaccine.
• lead to
hypersensitivi
ty reactions
• 1- Human diploid cell
vaccine (HDCV)
• It has less serious
reactions and less
common side effects.
• It gives rapid, high and
greater conversion of
antibody titre.
• 2- Rabies vaccine
adsorbed (RVA) is used
since the 1980s.
Active immunization:
Old
vaccines
Recent
vaccines

21. RABIES
Number of doses : 5 doses (each 1 ml).
Timing: The first dose is given as soon as possible
after the bite then on days 3,7,14 and 28 of the
first dose.
First
dose
Active immunization (Cont.):

22. RABIES
Active immunization (Cont.):
Intra muscular in
deltoid region
Antero-lateral upper
thigh
Never in gluteal region
Route and Site
X
Adults Infants

23. RABIES
It is of human
origin
All humans
bitten by animals
whose rabies
could not be
excluded
Who received
pre-exposure
vaccine
As soon as
possible up to
the 8th day of
starting the
regimen of
vaccination
Half dose is
given through
infiltration of
wound and the
other half given
IM
It neutralize the
virus in the bite
wound
Passive immunization:
Rabies immune globulin (RIG):
Origin Indication Not indicated
Time Route Action

24. RABIES
Pre-exposure immunization
by HDCV or RVA
Antibody titre is periodically examined
and if it declines a booster dose of the
vaccine is given
Three (3) doses post-exposure are
needed in case they are bitten by a
rabid animal at days (0, 7, 21 or 28
day). No RIG is needed
Veterinarians, Laboratory workers with rabies,
Dog handlers and Field workers
High risk group prophylaxis regimen:

25. RABIES
Pet dogs should be immunized and
received booster doses regularly
The health office should be informed
about any rabid animal or bitten human.
High risk groups should receive pre-
exposure immunization and booster
doses if the antibody titre declines.
Control

26. RABIES
Summary
Agent
Rhabdovirus
Reservoir
Urban type : Dogs ,
Cats
Wildlife type : Wolves ,
foxes , bats
Portal of Exit
Saliva
Mode of Transmission
Bite of infected
animal
Portal of Entry
Blood then Nervous
Host
Human and animals
Chain of
Infection