ZOONOSIS

1
ZOONOSIS
A disease primarily of animals which can be
transmitted to humans as a result of direct or
indirect contact with the infected animal
population
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ZOONOSIS

• Brucellosis
• Plague
• Listeriosis
• Anthrax
• Tularemia
• Erysipeloid

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Brucellosis (Malta fever)

• Dr. David Bruce attended to an epidemic among the
  British troops in Malta (1887)
• Isolated an organism from spleens of 4 fatal
  cases
• Fulfilled the Kochs postulate
• Linked the disease to goats milk on the island

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Brucella sp.

• Primarily affects people who work with animals or
  animal products (slaughterhouse workers,
  veterinarians, farmers, dairy workers)
• Four different species of Brucella are known to
  infect humans
• 100-200 cases seen per year

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Morphology physiology

• Fastidious aerobic
• Facultative intracellular

• Gram negative non motile cocobacilli

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Brucella reservoir
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Brucellosis in animals

• Transmitted by contact with infected tissue or
  milk (oral, aerosol or abrasion)
• Predilection for erythritol rich organs (breast,
  uterus, epididymis, ect.)
• Abortions, mastitis and sterility

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Brucellosis in humans

• Skin abrasion, conjunctivae, inhalation or
  ingestion
• Engulfed by neutrophils and monocytes (resistant
  to killing)
• Localize regional lymph nodes
• Infect phagocytic cells in the RE system and form
  granulomas

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Symptoms

• Aches, chills, fever (undulating)
• Drenching sweating
• Fatigue, myalgia, muscle weakness
• Relapse common

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Pathogenesis

• 5guanosine and adenine inhibit the degranulation
  of peroxidase-positive granules
• Host damage due to hypersensitivity

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Diagnosis

• Symptoms and history
• Blood culture on enriched media (slow 4-6 weeks)
• Organisms grow very slowly (6 weeks)
• Serology (titer gt640)
• Skin test with brucellergin - delayed-type

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Treatment

• Prolonged use (several months) of rifampin with
  tetracycline or streptomycin