RABIESRABIESEPIDEMIOLOGY & PREVENTIONDR. SYED SANOWAR ALIASSOCIATE PROFSSORCHS, UMDC

EPIDEMIOLOGYEPIDEMIOLOGYThe study of the The study of the DISTRIBUTION and and DETERMINANTS of health-related of health-related states or events in specified population states or events in specified population and application of this study to the and application of this study to the control of health problemscontrol of health problems

1. DISTRIBUTION OF DISEASE

A. When (time)B. Who (person)C. Where (place)

Descriptive Epidemiology Epidemiology

2. DETERMINANTS OF 2. DETERMINANTS OF DISEASEDISEASEA. WhyB. How

Analytical Epidemiology

DEFINITIONHuman Rabies is a viral infection of the

CNS usually transmitted by contamination

of a wound with saliva from a rabid animal

and is virtually

100%fatal once symptoms develop.

• Rabies is a zoonotic disease (a disease that is transmitted to humans from animals) that is caused by a virus.

GEOGRAPHIC DISTRIBUTION* Rabies Free Area in which no case has

occurred in human or any animal species for 2 years.

* Rabies is a major public problem in areas in which Dogs are uncontrolled.

* Rabies is present on all continents with the exception of Antarctica, but more than 95% of human deaths occur in Asia and Africa. Once symptoms of the disease develop, rabies is nearly always fatal.

Rabies Human DeathsRabies Human DeathsAnnual human deaths worldwide are

approximately 55,000; every 15 minutes a patient dies of rabies.

In the United States, there has been a mean of 3 deaths per year since 1990.

PAKISTANPAKISTAN• In Pakistan 2000 - 5000 cases / yr.• Rabies is endemic in Pakistan.• Human rabies is not a notifiable disease in Pakistan• The main vector for rabies in Pakistan is the domestic dog

KEY FACTS• Rabies is a vaccine-preventable viral disease which

occurs in more than 150 countries and territories.• Infection causes tens of thousands of deaths every

year, mostly in Asia and Africa.• 40% of people who are bitten by suspect rabid

animals are children under 15 years of age.• Dogs are the source of the vast majority of human

rabies deaths.

• Immediate wound cleansing and immunization within a few hours after contact with a suspect rabid animal can prevent the onset of rabies and death.

• Every year, more than 15 million people worldwide receive a post-exposure vaccination to prevent the disease – this is estimated to prevent hundreds of thousands of rabies deaths annually.

KEY FACTS

INCUBATION PERIODINCUBATION PERIODHighly variable

usually 20 – 180 days,

peak at 30 – 60 days

MODE OF MODE OF TRANSMISSIONTRANSMISSION

A- ANIMAL BITES : through rabid dog bites and the saliva of the biting animal contain the virus.

B- LICKS : licks on abraded skin and mucosa

transmit the disease.

Who is most at risk?•Dog rabies potentially threatens over 3 billion people in Asia and Africa.•Poor people are at a higher risk (cost = US$ 49 in Asia)•Although all age groups are susceptible, rabies is most common in children aged under 15 & majority are male.

Rabies attacks the Rabies attacks the Central Nervous Central Nervous SystemSystem

Watch as the rabies virus from an exposure on the leg spreads up the spinal cord to the brain and throughout the rest of the body.

Rabies virus entering the body.

Headache, fever, sore throatNervousness, confusionPain or tingling at the site of the biteHallucinations

– Seeing things that are not really there Hydrophobia

– “Fear of water" due to spasms in the throatParalysis

– Unable to move parts of the body Coma and death

Signs / SymptomsSigns / Symptoms

Clinical DiagnosisClinical Diagnosis

PREVENTION PREVENTION OF OF

HUMAN RABIESHUMAN RABIES

POST-EXPOSUREPRE-EXPOSURE

PREVENTION PREVENTION

Pre-exposure immunization in people•Travellers spending a lot of time outdoors, especially in rural areas.•People in certain high-risk occupations such as laboratory workers dealing with live rabies virus and other rabies-related viruses.•People involved in any activities that might bring them professionally or otherwise into direct contact with Dogs.•Children.•Living in or visiting high risk areas.

PRE- EXPOSURE PRE- EXPOSURE PROPHYLAXSISPROPHYLAXSIS1. Vaccination of domestic dogs1. Vaccination of domestic dogs2. Elimination of stray dogs2. Elimination of stray dogs3. Eliminating rabies in dogs3. Eliminating rabies in dogs4. Active Immunization Doses: 4. Active Immunization Doses: Day 0,7 and 28 (100% response) Day 0,7 and 28 (100% response)

WHO Recommended Pre-exposure

3-dose series intramuscular

Pre-exposure

Exposure: No Rabies immunoglobulin needed

day 0 7 21 or 28

3

Vaccine should never be administered in the gluteal region.

Was There An Exposure?Was There An Exposure?

A bite (penetration of the skin by

teeth) from a known or suspect rabid animalScratches, abrasions, open wounds (bleeding within

24 hrs), or mucous membranes (eyes) contaminated with saliva or other potentially infectious material from a known or suspect rabid animal

Other contact - such as petting an animal or contact with urine, feces - does NOT constitute an exposure

10 Day Confinement 10 Day Confinement & Observation Period& Observation PeriodClinical course usually less than 7 days - animal

dead before end of 10 days

Rabies Vaccination Status of Rabies Vaccination Status of AnimalAnimal

Lower risk if animal has been regularly vaccinated

But NO vaccine is 100% effectivePut as much weight on animal

behavior & health status

PREVENTION OF HUMAN PREVENTION OF HUMAN RABIESRABIES

POST- EXPOSURE PROPHYLAXSIS

A) if the animal shows signs of rabies orA) if the animal shows signs of rabies or dies within 10 days of observation. dies within 10 days of observation.B) If the biting animal can not be tracedB) If the biting animal can not be traced or or identified .identified .

In general if a biting dog does not die with in 10 days, Rabies is unlikely.

RABID DOG

PEPPost-exposure prophylaxis (PEP)•Local treatment of the wound. •Initiated as soon as possible after exposure; a course of potent and effective rabies vaccine that meets WHO recommendations.•Administration of rabies immunoglobulin, if indicated.

A) POST EXPOSURE PROPHYLAXSIS

LOCAL TREATMENT OF WOUND A. Mechanical removal By 1. Soap and water : using copious amounts of solution 2. Virucidal solution : 1% povidone-Iodine or 70% alcohol B. Suturing : not done C. Anti biotics & Antitetanus measures.

IMMUNIZATIONIMMUNIZATION1. ACTIVE IMMUNIZATION VACCINE

2. PASSIVE IMMUNIZATION IMMUNE GLOBULIN

1. Human rabies immune globulin2. Equine rabies immune globulin

VACCINE TYPESVACCINE TYPES NERVOUS TISSUE VACCINE (NTV) a- Antigenicity was poor

b- Multiple Injections were required.

c- Post vaccination Encephalitis was frequent problem.

This vaccines are still in use in many

places in the world .

Human diploid cells Human diploid cells vaccinevaccine(HDCV)(HDCV)

1.1. ACTIVE ACTIVE IMMUNIZATIONIMMUNIZATIONHuman Diploid Cells VACCINEHuman Diploid Cells VACCINE(HDCV)(HDCV)A. No. of doses : 05A. No. of doses : 05 Day 0, 3, 7, 14 and 28 Day 0, 3, 7, 14 and 28

B. Quantity : B. Quantity : 1 ml1 mlC. Route : Intra-muscular (Arms)C. Route : Intra-muscular (Arms)

Standard intramuscular regimen. One dose into deltoid on each of days:

Essential intramuscular Regimen

WHO Recommended PEP Schedule

5 vials 5 visits

day 0 3 7 14 28

Rabies immunoglobulin

2. PASSIVE IMMUNIZATION2. PASSIVE IMMUNIZATION IMMUNE GLOBULIN IMMUNE GLOBULINHuman rabies immune globulin

A. No. of doses : 01 as soon as possible

B. Quantity : 20 IU / Kg

C. Route : Half dose Intra-muscular (Arms)

Half dose subcutaneously

around the bite site

If Person having weight 60 KgIf Person having weight 60 KgHuman rabies immune globulinHuman rabies immune globulin20 IU / Kg20 IU / Kg20 x 60 = 1200 IU20 x 60 = 1200 IU600 IU I/M & 600 IU S/C around the 600 IU I/M & 600 IU S/C around the bite site.bite site.

EQUINE RABIES IMMUNE GLOBULINEQUINE RABIES IMMUNE GLOBULINA. No. of doses : 01 as soon as possibleA. No. of doses : 01 as soon as possibleB. Quantity : 40 IU / KgB. Quantity : 40 IU / KgC. Route : Half dose Intra-muscular (Arms)C. Route : Half dose Intra-muscular (Arms) Half dose subcutaneously Half dose subcutaneously around the bite site around the bite site after test dose after test dose Anaphylaxis is a rare. Anaphylaxis is a rare.

If Person having weight 60 KgIf Person having weight 60 Kg EquineEquine rabies immune globulin rabies immune globulin40 IU / Kg40 IU / Kg40 x 60 = 2400 IU40 x 60 = 2400 IU1200 IU I/M & 1200 IU S/C around the 1200 IU I/M & 1200 IU S/C around the bite site.bite site.

HYDROPHOBIA ?HYDROPHOBIA ?

Destruction of brain stem Destruction of brain stem neurons inhibitory to the neurons inhibitory to the neurons of the nucleus neurons of the nucleus ambiguous which control ambiguous which control Inspiration.Inspiration.

Why Hydrophobia does Why Hydrophobia does not occur in other not occur in other diseases ?diseases ?

Only Rabies combines Only Rabies combines brain stem Encephalitis brain stem Encephalitis with an intact Cortex and with an intact Cortex and maintenance of maintenance of consciousnessconsciousness