1. RABIES
Dr. D. Gracy Paulin
Assistant Professor
Department of Community Medicine
2. Learning objectives
At the end of this session, you should be able to
1. Summarize the burden of rabies
2. Describe the epidemiological features of rabies
3. Describe the steps in the management of dog bite
4. List the steps for the control of rabies
3. What are zoonoses?
Those diseases and infections which are naturally transmitted
between vertebrate animals and man
5. DIRECT ZOONOSES
Transmitted by direct contact, by fomite or by a
mechanical vector
No propagative or developmental change during
transmission
Eg: Rabies, Trichinosis, Brucellosis, anthrax
6. CYCLO-ZOONOSES
Require more than one vertebrate host species, but no
invertebrate host in order to complete the developmental cycle
of the agent
Obligatory and non-obligatory
Eg: Taeniases, Echinococcosis
8. META-ZOONOSES
Transmitted biologically by invertebrate vectors
In the vector, the agent multiplies or develops
There is always an extrinsic incubation period or prepatent period
Eg: Plague, Tick-borne encephalitis
9. SAPRO-ZOONOSES
Have both a vertebrate/invertebrate host and a non-animal
developmental site or reservoir
Organic matter including food, soil and plants are considered to be non
animal
Eg: Larva migrants and some Mycoses
10. CLASSIFICATION – Reservoir host
Anthropo-zoonoses – infections transmitted to man from lower
vertebrate animals
Examples??
Zooanthroponoses – infections transmitted from man to lower vertebrate
animals
Examples – Tuberculosis, amoebiasis, Diphtheria
Amphixenoses – infections maintained in both man and lower vertebrate
animals that may be transmitted in either directions. Universal
diseases.
Examples – Streptococcosis, Staphylococcosis.
11.
12. RABIES
Acute, highly fatal viral disease of central nervous system
Zoonotic disease of warm blooded animals caused by Lyssavirus
Type I
Transmitted by bites or licks of rabid animals
Also known as hydrophobia
ONLY COMMUNICABLE DISEASE THAT IS ALWAYS FATAL
13. HISTORICAL PERSPECTIVE
Oldest recorded infection of mankind
Anti rabies vaccine was the third developed vaccine, long
before the recognition of the nature of the virus
Louis Pasteur developed the first ARV in 1885
16. “RABIES FREE” AREA
Water is the natural barrier for rabies
Rabies free areas – Australia, China (Taiwan), Cyprus, Iceland, Ireland,
Japan, Malta, New Zealand, U.K, Islands of Western Pacific
Rabies free area in India???
When do you say an area to be “rabies free”?
17. AGENT FACTORS
Lyssavirus Type I belonging to Rhabdoviridae family, bullet shaped RNA
containing virus
Source of infection: saliva of rabid animals
Virus may be present in the saliva for 3 – 4 days before onset of symptoms
and during the course of illness till death
Highly resistant against cold, dryness and decay and can remain infectious
in dead bodies
Inactivated by formaldehyde, lipid solvents, sunlight, and antiseptics
Street virus and fixed virus
18. HOST FACTORS
All warm blooded animals including man
Man – dead end infection
Age group – 1-24 years
Laboratory staff working with rabies virus,
veterinarians, dog handlers, hunters and field
naturalists have higher risk
19. INCUBATION PERIOD
1-3 months but may very from 7 days to several years
Depends on site and severity of bite, no. of wounds, amount of virus
injected, species of biting animal, protection provided by clothing
and treatment taken
Incubation period tends to be shorter in bites on face, neck and
upper extremities.
20.
21. CLINICAL FEATURES
Prodromal symptoms – headache, malaise, sore throat, slight
fever, pain or tingling sensation at the site of bite (3 – 4 days)
Hydrophobia and aerophobia
Increased reflexes, muscle spasms, dilatation of pupils,
increased perspiration, lachrimation and salivation
22.
23. DIAGNOSIS
Clinical diagnosis by history of bite, hydrophobia and signs
and symptoms
Antigen detection by immunofluorescence of skin biopsy
Virus isolation from saliva and other secretions (CSF analysis)
Antibodies are not detectable in serum or CSF before eighth
day
24. TREATMENT
No specific treatment
Isolate and protect the patient from external stimuli
Relieve anxiety and pain by sedatives
Hydration and diuresis
Cardio respiratory support
To-date, only seven people are on record who have been stricken
with rabies and have survived
25. POST EXPOSURE PROPHYLAXIS
To neutralize the inoculated virus before it reaches
central nervous system
Single dose of rabies immunoglobulin
A course of vaccine
Local treatment of wound
26. LOCAL TREATMENT OF WOUND
• Washing the wound under running
tapwater for atleast 15 minutesMechanical
removal of virus
• Chemical treatment with virucidal agents –
alcohol, tincture or 0.01% aqueous solution
of iodine or povidone iodine
Inactivation of
the virus
• Infiltrate Immunoglobulin into the depth
and around the wound in category III
exposure
Neutralization
of the virus
29. Dose: 0.5 ml or 1 ml i.m. depending on
type of vaccine
30. 5-dose regimen (Essen)
prescribes one dose on
each of days 0, 3, 7, 14
and 28
4-dose abbreviated
multisite regimen (Zareb)
prescribes 2 doses on day
o (1 in each of 2 deltoid or
thigh sites) followed by 1
dose on each of days 7
and 21
31. 2-SITE INTRADERMAL REGIMEN (updated
THAI regimen)
Injection of 0.1ml at 2 sites (deltoid or thigh) on
days 0, 3, 7 and 28.
32. PEP FOR PREVIOUSLY VACCINATED
INDIVIDUALS
1 Dose delivered i.m or a CCV delivered i.d on days 0 and 3
(or)
Single visit 4-site i.d regimen: 4 injections of 0.1 ml equally
distributed over left and right deltoids and thighs
33. PASSIVE IMMUNIZAATION
Rabies immunoglobulin administered only once
At or as soon as possible after the first dose
Beyond 7th day, it is not indicated
Dose – 20IU/ Kg body weight
Should be administered as much as possible in or around the bite
site
Remaining, if any, should be administered distant from vaccination
site
34. Post-exposure prophylaxis can be
discontinued if the suspected animal is
proved by appropriate laboratory
examination to be free of rabies, or, in
the case of domestic animals, the
animal remains healthy 10 days
observation period starting from the
date of bite
35. PRE-EXPOSURE PROPHYLAXIS
I.M doses of 1ml or 0.5 ml depending on type of vaccine
I.D administration of 0.1 ml volume per site (one site each day)
On days 0, 7, 21 and 28
For persons who are at increased risk
Boosters are not needed but can be given periodically with
antibody titre monitoring
36. CONTROL MEASURES
Elimination of stray and ownerless dogs
Swift mass immunization
Registration and licensing of all domestic dogs
Restraint of dogs in public places
Immediate destruction of dogs and cats bitten by rabid
animals
Quarantine for about 6 months of imported dogs
Health education
39. 1. Rabies is
a. Direct zoonoses
b. Cyclo zoonoses
c. Meta zoonoses
d. Sapro zoonoses
40. 2. All are true about Rabies except
a. It is a RNA virus
b.It has fixed incubation period
c. Incubation period depends on site of bite
d.All bites with laceration on fingers are
category III injury
41. 3. For the treatment of category III dog bite,
all of the following are correct except
a. Give immunoglobulins for passive immunity
b.Give ARV
c. Immediately suture wound under antibiotic
coverage
d.Immediately wash wound with soap and
water
42. 4. A rabies free area is one with no
indigenously acquired cases
a. In man for 2 years
b.In man and animal for 2 years
c. In man for 1 year
d.In man and animal for 1 year
43. 5. Rabies free country is
1.China
2.Russia
3.Canada
4.France
44. SUMMARY
Classification of zoonoses
Burden of Rabies
Rabies free area
Epidemiological triad
Clinical features
Post exposure prophylaxis
Anti Rabies Vaccine
Rabies immunoglobulin
Control of rabies
Editor's Notes
“Crossing or jumping the species gap”
Impact of zoonoses – human health (increased case fatality rate), animal health (reduced productivity), health services (additional burden), economic burden (plaque has crossed ban on international travel), bioterrorism (plague and anthrax)
Just mechanical transmission. Already exist in nature in a single vertebrate host.
Obligatory – Man is a must to complete the life cycle. Eg: Taenia solium and saginate
Non-obligatory – man is an accidental host and may act as a dead end. Eg: Echinicoccus
Biologically – The infectious agent may multiply, develop or remain dormant.
Carnivores animals – dogs, cats, fox
56% of mortality in asia and 44% in Africa. Out of the global 55000 deaths, 20000 deaths occur in India.
3 to 10 mm/hour
Prodromal stage and acute neurologic stage (Stage of acute encephalitis and stage of brainstem dysfunction), Stage of coma and death
Hydrophobia – due to painful, violent, involuntary contraction of diaphragm, resp, pharyngeal and laryngeal muscles.
Initially there is no viraemia and the virus is not accessible to the body’s natural immune system.
Although 100% preventable, once the symptoms develop, it is almost 100% fatal. Hence PEP should be started asap.
Observe the dog or cat for 10 days.
Suturing may increase the risk of innoculation of virus deep into the wound. Even if unavoidable, it should be loose with minimum sutures after administering RIG. It should be done as late as possible. Bandage should also be avoided as the virus easily grows in anaerobic condition.
If the dog or cat has virus in the saliva, it will eventually show symtoms within 3 to 5 days and die in another 3 to 5 days.
