Epidemiology, Disease and Preventive Strategies of Rabies
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Transcript of Epidemiology, Disease and Preventive Strategies of Rabies
EPIDEMIOLOGY, DISEASE AND PREVENTIVE
STRATEGIES OF RABIES
Rabies Control Unit
OBJECTIVES
Epidemiology of rabies (Global and local situation)
Human rabies Post Exposure Treatment (PET)
Strategies for rabies control in Sri Lanka
GLOBAL SITUATION A global public health problem,
Neglected Tropical Disease affecting poor and vulnerable population
Present in all continents with the exception of Antarctica
Human deaths from rabies 55000 annually around the world.
>95% of human deaths occur in Asia and Africa
20,000 persons die in India annually (>1/3 of global deaths)
• Almost half of all rabies deaths occur in children under the age of 15 years in the world.
SRI LANKAN SITUATION 1972 - 2013
RABIES INCIDENCE2009 2010 2011 2012 2013
Human Rabies Deaths
52 41 38 28 16
Incidence of human rabies per 100,000 population
0.25 0.2 0.19 0.14
Elimination of rabies by 2020
ANIMAL RESPONSIBLE FOR HUMAN RABIES (2012)
Generally >95% of human deaths caused by dog-mediated rabies.
WHAT IS RABIES Rabies is a zoonotic disease (a disease
that is transmitted from animals to humans)
Affect Central nervous system of warm blooded animals
Domestic dogs are the most common reservoir
Rabies is a 100% vaccine-preventable
disease.
MODE OF TRANSMISSION Virus exist in saliva, nervous tissue,
urine, lymph and milk of warm blooded animals
Transmission via Bite/ scratch that introduces virus-
bearing Saliva. By viral contamination of existing
fresh wound/ mucous membrane. Skinning and handling of infected
carcasses Organ transplantation Ingestion
THE RABIES VIRUS Belongs to “Rhabdo virus” family, genus
Lysavirus Bullet-shaped (75 x 180 nm)
Enveloped
Single stranded RNA genome
Virus cannot grow unless it is inside a living cell
Dog rabies is characterized by clinical manifestations, including, changes to normal behavior, such as: Biting without provocation Eating abnormal items such as sticks, nails,
faeces, etc. Vocal changes (e.g. hoarse barking and
growling) or inability to produce sounds Excessive salivation or foaming from the mouth
WHAT HAPPENS WHEN AN INFECTED DOG BITES
HOW LONG WILL IT TAKE TO SHOW SYMPTOMS IN HUMANS
Generally between 20 and 90 days in 75% of cases.
But may be as short as 4 days or long as many years.
The shortest incubation periods are observed in patients with facial Bites
WHAT ARE THE SYMPTOMS 1 – Non specific prodrome
2 – Acute neurologic encephalitis
3 – Coma
4 - Death (99.999%)
NON SPECIFIC PRODROME 1 - 2 days - 1 week
Fever, headache, sore throat
Anorexia, nausea, vomiting,
symptoms of upper respiratory tract and gastrointestinal infections
Paresthesia or fasciculation at or around the site of inoculation of virus
Depending on whether the spinal cord or brain is predominantly affected Symptoms of either paralytic or furious rabies will then develop.
encephalitic = furious ~ 80%
paralytic = dumb ~ 20%
ACUTE NEUROLOGIC ENCEPHALITIS1 – 2 days to < 1 week Excessive motor activity, Excitation,
Agitation Confusion, Hallucinations, Delirium, Seizures, Muscle spasms, Meningism, Opisthotonic posturing Hypersalivation, Aphasia, Pharyngeal
spasms Incordination, Hyperactivity, Lacrimation, Salivation & Perspiration Hydrophobia or Aerophobia (50 -70% )
HYDROPHOBIA Inspiratory muscle spasms with or
without painful laryngo-pharyngeal spasms .
The reflex is provoked initially by attempts to drink water.
But later by a variety of. stimuli, like draught of air ( aerophobia) water splashed on the skin, irritation of the respiratory tract or eventually, by the sight, sound or mere mention of water.
DIAGNOSIS - HUMAN Suspect clinically and confirm by using tests.
No single test is sufficient.
Several tests are necessary to diagnose rabies ante-mortem (before death) in humans
Tests are performed on samples of saliva, serum, spinal fluid, and skin biopsies of hair follicles at the nape of the neck.
DIAGNOSIS Laboratory finding: Exclusion of other etiologies
Pathology: Formation of cytoplasmic inclusions in
neuron cell bodies : (Negri bodies )
Saliva (saliva,CSF, brain ) can be tested by virus isolation or reverse transcription followed by polymerase chain reaction (RT-PCR).
FOLLOWING AN ANIMAL BITEWounds should be washed immediately with soap and water for about 10 minutes.
Wounds should be cleaned thoroughly at the hospital with 70% alcohol or povidone iodine
Anti tetanus immunization should be inoculated when necessary
Antimicrobials should be prescribed if necessary to control bacterial infections
Patient Screening
Categorization of the exposure
Major exposureor
Minor exposure
Major exposuresSingle or multiple bites with bleeding on head, face, neck, chest, upper arms, palms, tips of fingers and toes and genitalia Multiple scratches with bleeding on head, neck and face Single or multiple deep bites on any part of the bodyContamination of mucus membranes with saliva Bites of wild animals with bleeding
Minor exposuresSingle, superficial bite or scratch with oozing of blood or scratches with bleeding on the lower limb, abdomen and back
Nibbling of uncovered skin
Contamination of open wounds with saliva
Multiple bites without bleeding or scratches with oozing of blood on any part of the body
Drinking raw milk of rabid cow or goat
Superficial bites and scratches of wild animal without bleeding
Animal screening
Healthy or sick
Vaccinated or unvaccinated
Observable or unobservable
Healthy Normal behavior of the animalBitten under provocation
Not Healthy Animal behavior not normalPresence any suspected symptoms/signs
UnobservableAnimal dead, killed, missing, stray or wild animal
Observable Animal should be put in a cage or leashed
Major exposures to dogs and cats
vaccinated ………… Should have minimum of 2 Rabies
vaccinations given not more than 2 years apart,
last vaccination given within 1 year of the incident
Minor exposures to dogs and cats :
Vaccinated …….. Has a minimum of 1 vaccination
Last vaccination given within 1 year of the incidentvaccination should be given at an age above 3 months
Major Minor
Healthy &Vaccinated &observable
Suspicious,sickor
unvaccinated observable
Delayobserve 14 daysPET sos
InitiatePET
observe 14 ddiscontinue ±
Lab confirmed
orunobservable
Initiate PET
continue fullcourse
Patient screening
Animal screening
Delayobserve 14 daysPET sos
Initiate PET
continue fullcourse
InitiatePET
observe 14 ddiscontinue ±
Healthy &Vaccinated &observable
Suspicious,sickor
unvaccinated observable
Lab confirmed
orunobservable
If PET is indicated:
Major category Anti Rabies immunoglobulin (RIG)
and Anti Rabies vaccine (ARV)
Minor category only Anti Rabies vaccine (ARV)
Anti Rabies Immunoglobulins (RIG)
1.Equine Rabies Immunoglobulin (ERIG)40IU/Kg body Weight
2. Human Rabies Immunoglobulin (HRIG)20IU/Kg body Weight
ANTI RABIES VACCINE (ARV) Inactivated anti rabies cell culture
vaccines availablePurified Chick embryo cell culture vaccine
(PCEC)Purified verocell rabies vaccine (PVRV)
DIFFERENT VACCINATION REGIMES- ARV-ID I D Schedule
D0 D3 D7 D14 D 30
ID 2 sites 0.1 ml per site 2 2 2 0 2
ID 4 sites 0.1 ml per site 4 2 2 0 2
The reduced volume required by ID vaccines, in comparison to the IM vaccine results in cost savings of 60-80%.
ID vaccination may be a more cost-effective option for high-flow clinics where the disease is endemic.
PREVENTIVE STRATEGIES Control of human rabies
Proper post exposure managementEncourage of pre exposure prophylaxis for
those engaged in occupations at higher risk of exposure rabies infections
Control of animal (dog) rabies Immunize of all dogs (domestic, community
and stray) through mass vaccination campaigns to achieve adequate coverage.
Need over 70% coverage to get Heard immunity
Dog population controlSterilize female dogs through appropriate chemical
and surgical methods
Environmental measures Garbage disposal, stray dog control in public
places (not by killing)
Inter-sectoral coordination Encourage other ministries to work towards
rabies elimination
Legal enactment Rabies Ordinance Dos registration Act
RABIES SURVEILLANCE Human rabies surveillance
Animal rabies surveillance
HUMAN RABIES SURVEILANCE Hospital notification MOH SPHI Weekly report Epidemiology Unit WER Quarterly Epidemiological Bulletin Special Investigation by MOH
ANIMAL SURVEILLANCE MRI
TH- Karapitiya
Peradeniya- Vet Department
Veterinary Investigation Centers – Department of animal production and health
Thank You