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