Zoonotic Diseases

1. Zoonotic Diseases Zoonosis: An infection or infectious disease transmissible under natural conditions from vertebrate animals to man. e.g., Rabies Anthrax Undulant fever/ brucellosis/ malta fever plague/ black death Tetanus ( locked jaw) Bovine tuberculosis etc.

2. Rabies • Primarily zoonotic disease of warm blooded animals particularly carnivores e.g., Dogs, foxes, cats, tigers, jackals, wolves. • Characterized by : • Classical hydrophobia • Long and highly variable incubation period • A short period of illness due to encephalitis ending in death. • Only communicable disease which is always fatal despite intensive care.

3. Source of infection: saliva of rabid animals • Reservoir of infection: in 3 epidemiological forms • Sylvatic (wild life) rabies – wild life cycle perpetuated by jackals, foxes, tigers etc; unidentified reservoir of infection. • Urban areas: From wild life to domestic dogs and maintained by them i.e., from dogs to dogs which leads to 99% of human cases. 3.Bat rabies: • Vampire bat – importance • Provides constant source of infection for wild animals thus enabling virus to be present in nature. • Agent: Lyssa-virus type I family Rhabdoviridae

4. Mode of transmission: • Animal bites • Licks over abraded/ un-abraded skin • Aerosols (respiratory) • Person to person rare but on record • Incubation period: • 6-60 days but highly variable otherwise at site, severity, no dose.

5. Epidemiology • Where: Approx. 40 countries including England, Japan, New Zealand are reported to be free of rabies because of strict importation of animals. • In Indo-Pak subcontinent, it is a major public health problem due to large number of stray dogs. • WHO(population at risk): • Dog-handlers • Lab-workers • Cave-explorers (bat rabies) • Veterainarians • Hunters • Wild-life officers etc. • When : endemic

6. P.O.C: In days 3-5 before the onset, rarely communicable from man to man. • Susceptibility/ Resitance: No natural immunity, prophylactic anti-rabies if started will prevent the disease. • Diagnosis: • History of exposure • Clinical signs/ symptoms • Microscopic examination • Characteristic eosinophilic inclusions(Negri –bodies)can be found inside nerve cells particularly in hippocampus and this is pathognomic sign in rabies.

7. Method of Control • Dog detention for 10 days, if dies – Rabid. • Pets – preventive vaccination • Destruction of stray dogs • Pets – leash application • Public – health education • If animal clinically rabid, even though the P.M brain examination fails to reveal negri-bodies vice versa or animal disappears after biting un-identified, un-provoked attack, bitten by wild animals – control of infected - person, contract environment.

8. Prevention • Post exposure prophylaxis: • Local treatment of wound • Immunization + ARS ( N.T.V D.E.V H.D.C.V) • Pre-exposure prophylaxis: Population at risk should be vaccinated • Post exposure treatment of persons previously vaccinated.

9. Beware of friendly animal(rabies and its treatment) • Mode of infection: • Animal bite • Contamination of wound by virus laden saliva • Media of transmission: • Saliva • Urine • Tears • Serum • Other body fluids

10. Routes of transmission: • Licks on damaged skin • Bites or scratches • Inhalation • Crossint through intact mucous membranes • Contamination of wounds • Incubation period: Highly variable ranging from few days to several years (commonly 30-90 days) depends upon the site & intensity of bite. Long incubation period makes rabies a suitable disease for post exposure prophylactic immunization.

11. Concept of therapy: • Neutralization or removal of virus before its lodging on the nerve • Enhancement of body immune system for long lasting antibody response. • No lab tests (antibodies titre) are required before initiation of anti-rabies treatment.

12. Prevention & Treatment • Pre-exposure prophylaxis (PEP): 3 standard IM doses of cell-cultured vaccine on day 0, 7, 21, 28. Persons who are in close contact or at high risk e.g., rabies research & diagnostic lab-workers, rabies biological product workers, spelunkers, veterinarians, animal control & wild life workers, animal hunters. • Post exposure management: • Local wound treatment • Vigorous cleansing of wound with soap water, detergent, ether, alcohol or aqueous sol. of Iodine. • Avoid wound suturing until and unless unevitable • Anti-tetanus injection • Analgesics & antibiotics symptomatically

13. Active immunization: Semple type( sheep brain suspension) – 2.5ml SC for cosecutive 14 days on anterior abdominal wall, followed by 2 boosters with 10 days interval & 3rd booster dose on 90th day • Intramuscular regimes: Essen schedule (5 doses) On day 0, 3, 7, 14 & 28 or 30 plus RIG (only once as soon as possible) • Reduced or Alternate regime: (4 doses) 2-1-1 on day 0, 7 & 21 • 2 doses on day 0 plus RIG • 3rd on day 7 • 4th (last) on day 21 • Previously immunized persons: Having adequate rabies antibody titre , if exposed again, require 2 doses of ant-rabies vaccine on days 0 & 7.

14. Recommended Standard Protective Rabies anitbody titre • Recommended WHO rabies antibody titer is 0.5IU/ml, 25-30 days after 5th or last injection • Rabies antibody titer has no significance before initiation of treatment. • If the titer is below the required level, booster dosage should be administered. • The protection afforded lasts for 6 months from the completion of anti-rabies treatment. • For long term protection, 1st booster after one year & subsequent booster after 5 years.

15. Method of Administration • Intramuscular injection into deltoid region or antero-lateral part of the thigh in small children. • Infiltrate half of the dosage of RIG in & around the wounds locally & remaining should be administered distant from the site of vaccine administration. • Never inject vaccine or sera into gluteal region because of dalayed absorption. • Use different syringes each time.

16. Dosage • Human Rabies Immune-globulin (HRIG) 20IU / kg body weight. • Equine Rabies Immune-globulin (ERIG) 40IU / kg body weight. • Dilute 2-3 folds with sterile saline solution if the calculated dosage of RIG is insufficient to infiltrate all wounds. • Skin testing should be performed with ERIG and if found to be positive, treatment should proceed but precautionary measures should be at hand & observe the patient for at least one hour after injection. A negative skin test must never reassure the physician that no anaphylactic reaction will occur.

17. WHO Guidelines for Post exposure treatment

18. Exposure to hare and rodent seldom, if ever, requires specific anti-rabies treatment. • If an apparently healthy dog or cat in or from a low risk area is placed under observation, it may be justified delaying the specific treatment. • This observation period applies only to dogs and cats.

19. Anthrax • This is an acute bacterial infection of animal transmissible to man. • ANTHRAX / ANTHRACOSIS • Organism: Bacillus-Anthracis • Source: tissue, skin & hides, hair & wool of animals dying of anthrax. • Reservoir: farm animals / infected cattle, sheep, goats & horses. • Occurrence: wide spread in agricultural areas

20. Mode of Transmission According to Clinical form 1-Cutaneous anthrax or malignant pustule – contact of spores over skin of population at risk. Sequence of events: • Small red indurate area • Later becomes edematous and soft • Lastly become hard, edematous & necrotic • Also characterized by lymphadenopathy, cellulitis & septicemia.

21. 2- Inhalational anthrax or Wool sorter’s disease (W.S.D) or pulmonary anthrax Occurs due to inhalation of infected material 3- Intestinal or ingestion material: Ingestion of infected meat / other material. Incubation period 1-7 days

22. Epidemiology • When : endemic • Where : agricultural / industrial area • Who : agriculturist, hide-workers, butchers, shepherds, wool factory workers, tanners in tannery factory, veterinarians, farm workers / farmers etc. • Diagnosis: • Shears from skin lesions (cutaneous anthrax) • Sputum examination – W.S.D • Blood by culture

23. Preventive/Control Measures 1-Animals: Sick must be isolated and treated. Carcases 6feet buried or burnt. • Precaution: Never opened or bled Vaccination with alum precipitated antigen of animals. 2-Factors: • Control of effluents • Trade-waste • Dust control / ventilation

24. 3- At Community level: • Health education • Medical care of skin 4- Material : Disinfection: • Hair – steaming • Wool – formaldehyde • Hides – bin chloride of formic acid /HCl • In epidemic – quarantine for 10 days.

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