Zoonosis

1. Zoonosis Yersinia Brucella Francisella

2. ZOONOSIS A disease, primarily of animals, which is transmitted to humans as a result of direct or indirect contact with the infected animal population

3. Overview Morphology & Physiology Epidemiology Symptoms Pathogenesis Diagnosis Treatment Brucellosis

4. Brucella: Overview • Primarily a disease of animals. • Common where significant disease among domestic animals. • Common names- Undulant fever, Malta fever, Mediterranean remittent fever. • Brucella can go through intact skin. • Facultative intracellular bacteria

5. Morphology & Physiology • Small gram-negative coccobacillus • Grows slowly (7 days), at 370 C. • On subculture, a minimum of 48 h growth • Aerobic growth on Chocolate agar and Sheep blood agar • Will not grow on MacConkey or Eosin methylene blue (EMB) agar

6. Morphology & Physiology • Non-pigmented and non-hemolytic • Non-motile • Oxidase: positive • Catalase: positive • Urease: strongly positive, less than 2 hours. Some species within 5 minutes.

7. Microscopic Characteristics • Brucella spp. • poorly staining • small gram-negative coccobacilli • seen mostly as single cells • appearing like “fine sand”

8. Brucellamelitensis colonies A. Grows slowly on most standard laboratory media. Usually not visible at 24h. B. Pinpoint, smooth, translucent, non-hemolytic at 48h.

9. Public Health AspectsBrucella: Sources • Brucellosis caused by 1 of 4Brucella species: • B. abortus Some strains require 5% CO2 on initial isolation.

10. 2. B. melitenus Sheep Camels Goats

11. 3. B. suis

12. 4. B. canis

13. Individuals who work with unvaccinated animals B. abortusand B. suis Infections result from: direct contact inhalation Individuals who ingest unpasteurized dairy products B. melitensisis the most common agent 2 patient populations

14. Host Animal - Brucellosis • Asymptomatic or mild disease. • Predilection for organs rich in erythritol (breast, uterus, placenta, epididymis). • Causes sterility, abortions or carrier state in non-human animals.

15. Human - Brucellosis

16. Pathogenesis Brucella mucosal epithelium Transported to lymph nodes, spleen, liver and bone marrow.

17. Pathogenesis Lysozome X Phagosome

18. No exotoxins LPS does not activate the alternative complement pathway Acute lymphadenitis Granulocyte production in lymphatic tissue, spleen, liver, bone marrow, lymph nodes and kidneys. A potential bioterrorist agent Pathogenesis

19. Diagnosis • Symptoms and history • Serological agglutination tests • Culture • Blood and bone marrow cultures • Spleen, liver, joint fluid or abscesses

20. Treatment Tetracycline, doxycycline, or trimethoprimsulfamethoxazole in combination and rifampin or gentamicin for 6 weeks to prevent reoccurring infection.

21. Tularemia: (Francisellatularensis) Gram stain

22. Primary reservoir in US Rabbits and muskrats Insect vectors Ticks Infection via Insect bites Handling contaminated animal tissues Inhalation of aerosols Ingestion of contaminated food or water Exposure in a laboratory setting Tularemia: Overview

23. Tularemia: Overview • Gram-negative coccobacilli. • Low infectious dose • Two subspecies of F. tularensis: • subspecies tularensis(type A) • subspecies holarctica(type B)

24. Morphology & Physiology • Tiny gram-negative coccobacillus • Nonmotile, encapsulated • Aerobic slow growing (48 hours) 35-370 C • Fastidious organism requires sulfhydryl (cysteine, IsoVitaleX) supplementation for growth • Grows wells on • Chocolate agar • Buffered charcoal yeast extract agar

25. Colony Characteristics • After 48 hours incubation • Colonies • Very small • white to gray to bluish-gray • Will not grow on MacConkey or EMB plates. F. tularensis on chocolate agar 48 hours growth.

26. Microscopic Characteristics Tiny, faintly staining, pleomorphic gram-negative rods (0.2-0.5 mcm X 0.7-1.0 mcm) are noted; cells are smaller than those of Haemophilus species.

27. Phenotypic Characteristics • Grows slowly at 35-370 C • Oxidase-negative • Weakly catalase-positive (may be negative) • Urea-negative • Nitrate-negative • Non-motile • Beta-lactamase-positive • Satellite or XV test-negative (unlike Haemophilus)

28. Tularemia: Public Health • Modes of humans infection • Bite of infected flies, or ticks • Handling contaminated animal tissues or fluids • Direct contact with or ingestion of contaminated water, food, or soil • Inhalation of infective aerosols (most likely BT route)

29. Tularemia: Public Health • Endemic in US • Majority of cases occur May – September (tick exposure) or winter (hunters). • Most in rural areas. • Arkansas, Missouri and Oklahoma

30. Symptoms • Incubation period: 3-5 days (range 1-21 days) • Clinical presentation can be divided into groups • Ulceroglandular (45-85%) /glandular (10% to 25%) • Typhoidal • Pneumonic • Oculoglandular • Oropharyngeal/Gastrointestinal • Prominent lymphadenopathy • Recovery followed by permanent immunity

31. Tularemia Clinical Types Clinical presentation based on the route of infection

32. Typhoidal tularemia • Bacteremia- Sepsis • Fever, chills, headache, myalgias, malaise, sore throat, and anorexia. • Likely bioterrorism presentation.

33. Pneumonic tularemia • Entry into lungs via • Aerosols • hematogenous • Severe atypical pneumonia • Likely BT presentation

34. Pathogenesis

35. Facultative intracellular pathogen • Capsule protects against complement killing • Macrophage uptake • bacterial surface polysaccharides • serum complement • complement C3 receptors • LPS - O antigen • prevents maturation of the phagosome • multiply to high levels in cytosol • Bacterial release via apoptosis

36. Diagnosis • Symptoms & History • Direct staining of clinical specimens with a fluorescein-labeled antibodies. • Serum antibody titers of 1:160 or greater • Culture on cysteine-rich media • Notify Laboratory personnel if you suspect Francisella since it is HIGLY INFECTIOUS

37. Treatment of Tularemia • Prompt removal of ticks and insect repellent can prevent disease. • Antibiotics • Streptomycin is the drug of choice

38. Yersinia

39. Overview: 3species cause human disease • Yersinia pestis • Yersinia enterocolytica • Yersinia pseudotuberculosis

40. Overview: Plague • Yersinia pestis; a gram-negative bacterium. • Three forms of clinical illness; • Bubonic • Septicemic • Pneumonic • Pneumonic is the only one transmitted through aerosals.

41. Plague: Overview • Natural disease of rodents • Fleas that live on rodents transmit the bacteria to humans, in the bubonic form. • This disease occurs in many areas of the world, including the United States.

42. Plague: Overview • U.S. averages 13 cases/yr (17 in 2006) • Plague is endemic in the desert southwest. • Most cases occur in summer.

43. Microscopic Characteristics • Y. pestis appear as single cells or short chains of plump, gram-negative rods.

44. Microscopic Characteristics Gram stain: • In direct smears, bacterial cells may be inside or outside of leukocytes. • The Gram smear morphology is suggestive but not specific for Y. pestis. Bipolar staining of a plague smear prepared from lymph aspirated from a bubo of plague patient.

45. Microscopic Characteristics • Bipolar staining occurs when using Wayson, or Giemsa stain. CDC

46. Colony Characteristics • Grows well on most standard laboratory media. • Sheep Blood Agar • Gray-white translucent colonies • Pinpoint, gray-white, non-hemolytic at 24 hours Blood agar plate of Yersinia pestis at 48 hours. CDC/Dr. Brodsky

47. Y. pestis: Physiology • Non-motile • Pleomorphic gram-negative bacillus • Urease, and oxidase negative • Facultative anaerobe • Optimal growth at 28o C • Facultative intracellular parasite

48. Public Health Aspects of Plague • Fleas carry Y. pestis in their intestinal tract. • When feeding the fleas regurgitate uncapsulated organisms. • Bacteria re-encapsulate and grow. • Progeny are resistant to intracellular killing

49. Yersiniapestis life-cycle

50. Plague - Clinical types • Bubonic • infected lymph nodes. • Pneumonic (most likely BT presentation) • transmissible by aerosol; deadliest. • Septicemic • blood-borne organisms.