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Zoonotic diseases

Zoonotic diseases. Classification- Anthropozoonosis – Zooanthroponosis - Amphixenosis -. 4 categories of zoonosis -. Direct zoonosis - direct contact contact with fomite mechanical vector e.g rabies, brucellosis

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Zoonotic diseases

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  1. Zoonotic diseases Classification- Anthropozoonosis – Zooanthroponosis- Amphixenosis-

  2. 4 categories of zoonosis- • Direct zoonosis- direct contact contact with fomite mechanical vector e.g rabies, brucellosis • Cyclo-zoonosis- more than 1 vertebrate host no invertebrate host e.gtaeniasis,echinococcosis

  3. Categories .. • Meta-zoonosis- invertebrate vectors vertebrate vector e.g plague, schistosomiasis • Sapro- zoonosis- vertebrate host + non-animal site e.g larva migrants

  4. Rabies

  5. Epidemiology • Magnitude of the problem : • Approximately 55,000 people die from rabies each year • majority of these deaths occurring in Asia and Africa. • In Africa, there are estimated at 24,000 (or 4 per 1,00,000 population) deaths annually.

  6. In India alone, 20,000 deaths are estimated to occur annually, i.e. 2 per 1,00,000 population • Rabies free areas ?

  7. Agent • : Lyssavirus type 1 • Rhabdoviridae family. • This RNA virus is bullet shaped • 100 - 300 nm in length and 75 nm in diameter. • lipid envelope , spike like projections.

  8. Rabies Virus

  9. Electron Microscope ViewNegatively Stained Rabies Virus

  10. Reservoir of infection • Urban- dogs & cats • Wild-life ( sylvatic)- jackal,fox • Bat rabies- vampire bats

  11. Source of infection • Saliva of rabid animals • 4-6 days before onset of symptoms till death of animal • virus-Not in all rabid animals saliva

  12. Carrier • Dogs

  13. Host • all age groups are susceptible • most common in children aged below 15 years • High risk group-

  14. Incubation period • Man- • four days to as long as 19 years. • The usual duration is between 20 to 90 days. • 95% cases have incubation period less than one year. • Factors affecting -

  15. Transmission Animal bites- Licks- on abraded skin/ mucosa Aerosols – bats/labs Person –person- corneal/organ transplant

  16. Transmission • Almost all transmission is by bite • 50 times greater risk than a scratch • Pathogenesis

  17. Animal Behavior • Classic Picture of rabid, dog foaming at the mouth… • aggressive behavior, ataxia, irritability, anorexia, lethargy or excessive salivation.

  18. clinical features in man • Prodromal stage -3-5 days • Sensory- • Motor- muscle spasms • Sympathetic-salivation,perspiration • Mental system- • hydrophobia

  19. Rabies in man • Diagnosis- • Ag detection –immunofluorescence of skin biopsy • Virus isolation • Treatment

  20. Prevention and Control • Rabies Vaccines 1)Nerve Tissue Vaccine (NTV) 2) Duck embryo vaccine (DEV) 3)Cell culture vaccine a) human diploid cell vaccine(HDC) b)tissue culture –animal cell vaccine

  21. HDC- human diploid fibroblast cells • Safe, highly potent • Animal vaccines- chick embryo fibroblast,dog kidney cells

  22. Prevention of human rabies • Post-exposure prophylaxis • Pre- • Post-exposure Rx of patients previously vaccinated.

  23. Post-exposure Rx • Local treatment of wound- cleansing savlon, cetavlon ? suturing ? anti-rabies serum antibiotics & TT observe animal for 10 days

  24. Indications for anti-rabies treatment • Animal shows signs /dies within 10 days • Biting animal cant be traced • Unprovoked bites • Lab tests- FRA, Negri bodies • All bites by wild animals

  25. Post exposure prophylaxis

  26. Rabies Immunoglobulin (RIG) • equine (ERIG) • human (HRIG) • all category III exposures and • in category II exposures involving immunodeficient individuals.

  27. RIG.. • infiltrated into and around the wounds. • The remainder should be administered by deep intramuscular injection at an injection site distant from the vaccine injection site. • In case of multiple wounds, the RIG should be diluted with normal saline to make sufficient volume to ensure infiltration at all wound sites

  28. Vaccine –as a Pre- exposure prophylaxis • 1 ml im/ 0.1 ml id • O , 7 , 28 • Booster injections every 2 yrs

  29. Post exposure Rx of previously vaccinated • 0, 3 ,7

  30. Rabies in Dogs • Incubation period- 3-8 wks • 2 forms- • Furious rabies • Dumb rabies • Lab – • Vaccination of dogs- • Nervous tissue vaccine-booster every yr • Live vaccine-booster every 3 yrs

  31. Control of urban rabies • Registration & licensing of all domestic dogs • Immediate destruction of dogs bitten by rabid animal • Imported dogs- quarantine -6 mths • Health education • Oral vaccine?

  32. How to avoid dog bites. • Never disturb a dog who is….. • Eating • Sleeping • Caring for puppies • Do not ….. • Look a dog straight in the eye • Throw anything at a dog • Run near dogs

  33. How to avoid dog bites. • If a growling dog comes near you….. • ….stand still with your arms down, pretend you are a tree.

  34. How to avoid dog bites. • If a dog attacks you…. • ….. curl into a ball and protect your face, pretend you are a rock.

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