Transcript Rabies virus

RABIES
Hydrophobia, Lyssa
• Rabies is an infectious acute viral encephalomyelitis
disease that is almost always fatal following the onset
of clinical signs.
• Most often transmitted through the bite of a rabid
animal
Rabies virus
• A rhabdovirus of the genus Lyssavirus
• bullet-shaped;
• 45-100 nm in diameter; 100-430 nm long.
• Rabies is a vaccine-preventable viral disease which occurs in more
than 150 countries and territories.
• 40% of people who are bitten by suspect rabid animals are children
under 15 years of age.
• Immediate wound cleansing with soap and water after contact with a
suspect rabid animal can be life-saving.
• Every year, more than 15 million people worldwide receive a post-bite
vaccination. This is estimated to prevent hundreds of thousands of
rabies deaths annually.
Symptoms
• The initial symptoms of rabies are fever and often pain or an unusual or
unexplained tingling, pricking or burning sensation (paraesthesia) at the
wound site.
• As the virus spreads through the central nervous system, progressive, fatal
inflammation of the brain and spinal cord develops.
• headache
• Excitation
• Agitation
• Hyper-salivation
• Difficulty swallowing
• Hydrophobia
• After a few days, death occurs by cardiorespiratory arrest.
Epidemiology
Occurrence: World wide disease with an estimated 65 000 - 87 000
deaths, almost in developing countries particularly Asia…
Reservoir Wild and domestic animals including:
• dogs
• Skunks
• Bats
• Foxes , Wolves
• Raccoons
Transmission …
• Virus-laden saliva of rabid animal introduced through a bite or
scratch…
• People are usually infected following a deep bite or scratch by an
infected animal. Dogs are the main host and transmitter of rabies.
They are the cause of human rabies deaths in Asia and Africa in more
than 95% of all cases.
• Bats are the source of most human rabies deaths in the Americas. Bat
rabies has also recently emerged as a public health threat in Australia
and western Europe.
• Transmission can also occur when infectious material – usually saliva
– comes into direct contact with human mucosa or fresh skin wounds.
• Human-to-human transmission by bite is theoretically possible but
has never been confirmed.
• Rarely, rabies may be contracted by inhalation of virus-containing
aerosol or via transplantation of an infected organ. Ingestion of raw
meat or other tissues from animals infected with rabies is not a
confirmed source of human infection.
Types of Exposure
Bite
 Any penetration of the skin by teeth
constitutes a bite exposure
Nonbite
 The contamination of open wounds,
abrasions,
mucous
membranes
or,
theoretically,
scratches
(potentially
contaminated with infectious material from
a rabid animal) constitutes a nonbite
exposure
PPT-
10
Incubation period
• The incubation period usually 3-8 weeks… rarely as
short as 9 days or as long as 7 years; depend on:
• Wound severity
• Wound site as relation to nerve supply, distance from
the brain.
• Amount and strain of virus.
• Protection provided by clothing and other factors.
Period of communicability
• In dogs and cats 3-7 days before onset of clinical signs and
throughout the course disease.
• Bats shed virus for 12 days before evidence of illness..
• Skunks shed virus for at least 8 days before onset of clinical
signs…
Diagnosis
• No tests are available to diagnose rabies infection in humans before
the onset of clinical disease, and unless the rabies-specific signs of
hydrophobia or aerophobia are present, the clinical diagnosis may be
difficult. Human rabies can be confirmed post mortem by various
diagnostic techniques aimed at detecting whole virus, viral antigens
or nucleic acids in infected tissues (brain, skin, urine or saliva).
Prevention
Prevention
• Eliminating rabies in dogs
• Rabies is a vaccine-preventable disease. Vaccinating dogs is the most
cost-effective strategy for preventing rabies in people.
• Maintain active surveillance for rabies in animal.
• Detain and clinically observe for 10 days any health – appearing dog
or cat known to have bitten a person (unwanted dogs & cats may be
sacrificed immediately and examined for rabies by fluorescent and
microscopy)
• Immediately sacrifice unimmunized dogs and cats bitten by known
rabid animal…
Pre-Exposure Vaccination
• Individual at high risk( veterinarians, work with rabies
in laboratory settings , animal control and wildlife
officers are just a few of the people who should
consider rabies pre-exposure vaccinations
• If you are traveling to a country where rabies is
widespread, you should consult your doctor about the
possibility of receiving pre-exposure vaccination against
rabies
• Although pre-exposure vaccination does not eliminate
the need for additional therapy after a rabies exposure,
it simplifies management by eliminating the need for
rabies immune globulin and decreasing the number of
doses of vaccine needed.
Primary Vaccinations
Type
Name
Route
Indications
Human Diploid
Cell Vaccine
(HDCV)
Imovax® Rabies
Intramuscular
Pre-exposure or
Post-exposure
Purified Chick
Embryo Cell
Vaccine (PCEC)
RabAvert®
Intramuscular
Pre-exposure or
Post-exposure
PPT-
22
Primary Vaccination
Three 1.0-mL injections of HDCV or PCEC vaccine should
be administered intramuscularly (deltoid area) -- one
injection per day on days 0, 7, and 21 or 28
• Frequent Risk
• Persons in the frequent risk group should have a serum
sample tested for rabies antibody every 2 years; if the
titer is less than complete neutralization, the person
also should receive a single booster dose of vaccine.
Post-exposure prophylaxis (PEP)
• Post-exposure prophylaxis (PEP) means the treatment of a bite victim that
is started immediately after exposure to rabies in order to prevent rabies
from entering the central nervous system which would result in imminent
death.
This consists of:
• local treatment of the wound, initiated as soon as possible after
exposure;
• A course of potent and effective rabies vaccine that meets WHO
standards;
• The administration of rabies immunoglobulin (RIG), if indicated.
Effective treatment soon after exposure to rabies can
prevent the onset of symptoms and death.
Post-exposure
prophylaxis
(PEP)
management
depends on :
• Type of contact with with suspect rabid animal
• Vaccination status of individual:
Categories of contact and recommended post-exposure prophylaxis (PEP)
Categories of contact with suspect rabid animal
Post-exposure prophylaxis
measures
Category I – touching or feeding animals, licks on intact
None
skin
Category II – nibbling of uncovered skin, minor
scratches or abrasions without bleeding
Immediate vaccination and local
treatment of the wound
Category III – single or multiple transdermal bites or
scratches, licks on broken skin; contamination of
mucous membrane with saliva from licks, contacts with
bats.
Immediate vaccination and
administration of rabies
immunoglobulin; local treatment of the
wound
All category II and III exposures assessed as carrying a risk of developing
rabies require PEP. This risk is increased if:
• The biting mammal is a known rabies reservoir or vector species;
• The animal looks sick or displays an abnormal behaviour;
• A wound or mucous membrane was contaminated by the animal’s saliva;
• The bite was unprovoked;
• The animal has not been vaccinated;
• In developing countries, the vaccination status of the suspected animal
alone should not be considered when deciding whether to initiate
prophylaxis or not.
Rabies post-exposure prophylaxis (PEP) schedule
Vaccination status
Not previously
vaccinated
Intervention
Wound cleansing
Human rabies immune
globulin (HRIG)
Vaccine
Previously
vaccinated**
Wound cleansing
HRIG
Vaccine
Regimen*
All PEP should begin with immediate thorough cleansing of all
wounds with soap and water. If available, a virucidal agent
(e.g., povidine-iodine solution) should be used to irrigate the
wounds.
Administer 20 IU/kg body weight. If anatomically feasible, the
full dose should be infiltrated around and into the wound(s),
and any remaining volume should be administered at an
anatomical site (intramuscular [IM]) distant from vaccine
administration. Also, HRIG should not be administered in the
same syringe as vaccine. Because RIG might partially suppress
active production of rabies virus antibody, no more than the
recommended dose should be administered.
Human diploid cell vaccine (HDCV) or purified chick embryo
cell vaccine (PCECV) 1.0 mL, IM (deltoid area†), 1 each on
days 0,§ 3, 7 and 14.
All PEP should begin with immediate thorough cleansing of all
wounds with soap and water. If available, a virucidal agent
such as povidine-iodine solution should be used to irrigate the
wounds.
HRIG should not be administered.
HDCV or PCECV 1.0 mL, IM (deltoid area†), 1 each on days 0
and 3.
Local treatment of the wound
• This involves first-aid of the wound that includes immediate and
thorough flushing and washing of the wound for a minimum of 15
minutes with soap and water, detergent, povidone iodine or other
substances that kill the rabies virus.
Control of patients and contacts
- Report to local health authority..
- Isolation: Contact isolation for respiratory secretion
for duration of illness.
- Concurrent disinfection: OF saliva and articles.
- Immunization of contacts: Contacts who have an
open wound or mucus membrane exposure to
patient’s saliva must received specific anti-rabies
treatment.
- Investigation of contacts and source of infection.
WHO & Elimination of Rabies
• Rabies, a zoonotic disease, requires close co-ordination between
animal and human health sectors at the national, regional and
continental levels.
• In December 2015, a global framework to reach zero human rabies
deaths by 2030 was launched by WHO and the World Organisation for
Animal Health (OIE), in collaboration with the Food and Agriculture
Organization of United Nations (FAO) and the Global Alliance for
Rabies Control. This initiative marks the first time that the human and
animal health sectors have come together to adopt a common
strategy against this devastating but massively neglected disease.
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