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Rabies
- 1. RABIES Dr. D. GracyPaulin Assistant Professor Department of Community Medicine
- 2. Learning objectives At theend 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? Thosediseases and infections which are naturally transmitted between vertebrate animals and man
- 4. CLASSIFICATION OF ZOONOSES Etiological agents Transmission cycle Direct zoonoses Cyclozoonoses Metazoonoses Saprozoonoses Reservoir host Anthropozoonoses Zooanthroponoses Amphixenoses
- 5. DIRECT ZOONOSES Transmittedby 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 morethan 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
- 7. OBLIGATORY AND NON-OBLIGATORYCYCLOZOONOSES
- 8. META-ZOONOSES Transmitted biologicallyby 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 botha 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 – Reservoirhost 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.
- 12. RABIES Acute, highlyfatal 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 Oldestrecorded 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
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- 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 LyssavirusType 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 Allwarm 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 1-3months 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.
- 21. CLINICAL FEATURES Prodromalsymptoms – 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
- 23. DIAGNOSIS Clinical diagnosisby 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 specifictreatment 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 OFWOUND • 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
- 27. “SUTURING THE WOUND SHOULDBE AVOIDED AS A RULE”
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- 29. Dose: 0.5 mlor 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 PREVIOUSLYVACCINATED 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 Rabiesimmunoglobulin 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 canbe 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.Mdoses 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 Eliminationof 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
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- 39. 1. Rabies is a.Direct zoonoses b. Cyclo zoonoses c. Meta zoonoses d. Sapro zoonoses
- 40. 2. All aretrue 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 thetreatment 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 rabiesfree 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 freecountry is 1.China 2.Russia 3.Canada 4.France
- 44. SUMMARY Classification ofzoonoses Burden of Rabies Rabies free area Epidemiological triad Clinical features Post exposure prophylaxis Anti Rabies Vaccine Rabies immunoglobulin Control of rabies
Editor's Notes
- #4 “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)
- #5 Etiological agent: Bacterial – brucellosis, leptospirosis, Viral – Rabies, JE, Ricketssial and chlamydial – q fever, scrub typhus, parasitic – toxoplasmosis, VLM, Hydatidosis
- #6 Just mechanical transmission. Already exist in nature in a single vertebrate host.
- #7 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
- #9 Biologically – The infectious agent may multiply, develop or remain dormant.
- #13 Carnivores animals – dogs, cats, fox
- #15 56% of mortality in asia and 44% in Africa. Out of the global 55000 deaths, 20000 deaths occur in India.
- #21 3 to 10 mm/hour
- #22 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.
- #24 Initially there is no viraemia and the virus is not accessible to the body’s natural immune system.
- #26 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.
- #28 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.
- #35 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.