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Zoonosis Dr Wafaa Jamal
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WLO Define the term zoonoses To know the mode of transmission of different types of zoonotic infections Describe common examples of bacterial, viral and parasitic zoonotic infection
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Objectives Describe different modes of transmission of the diseases To be familiar with the common causative pathogens Understand the principles of management of these infections
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Zoonoses Infectious diseases that can be transmitted from vertebrates (domestic & wild animals) to human Animal may or may not show obvious illness but can infect man Types: bacteria, viruses or parasites
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Mode of transmission 1. Direct contact: with animal or its products e.g. Products of conception (Brucellosis) Infected bone meal (anthrax) Fish handler (erysipeloid) Abattoir worker (Q fever)
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Mode of transmission 2. Inhalation: of excreta, secretions Dropping (psittacosis) Spores in wool (pulmonary anthrax) Secretions (Brucellosis) 3. Ingestion of food and milk products Salmonella, Campylobacter, Brucella, Q fever, Toxoplasma
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Mode of transmission cont… 4. Saliva: bites or licks from infected animals e.g. rabies, Pasteurella multocida infection 5. Faeces: contaminate food, soil, surfaces handled by humans e.g. salmonellosis, hydatid disease, tetanus
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Mode of transmission cont… 6. Urine Handling of animals directly or via swimming in contaminated water (Leptospirosis) 7. Blood and life tissues: rare Animal house attendants, zoo & lab workers: direct handling or inhaling aerosols from infected body or tissue of monkeys (Marburg virus disease, yellow fever)
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Brucellosis Gram-negative coccobacilli Incubation peroid: 1week - 6months SpeciesAnimal reservoirGeographical distribution Brucella mellitensisgoats & sheepMediterranean area Brucella abortuscattleWorldwide Brucella suispigsUSA, Denmark
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Brucellosis Epidemiology Ingestion of unpasteurized milk, milk products Direct contact with vaginal secretions, product of conception Inhalation: (laboratory accidents) Pathogenesis: intracellular in cells of reticuloendothelial system, inaccessible to PMN No person to person spread (few exception)
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Brucellosis Clinical features Fever, arthritis, splenomegaly, hepatomegaly, CNS, orchitis, endocarditis Diagnosis Serology: standard agglutination test, ELSA Culture Treatment: rifampicin & doxycycline for 6 weeks
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Anthrax Bacillus anthacis: Gram-positive bacilli, spore Disease of cattle, sheep Spores survive for years Acquire infection Occupational disease: workers handling contaminated hides, hair, wool of sheep, bone meal
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Anthrax Pathogenesis Capsule – Polypeptide: D-glutamic acid – Inhibit opsonization, phagocytosis Plasmid encoded Toxin (binary toxin) – Protective factor: bind to receptor on macrophage – Lethal factor: inhibit cell function – Oedema factor: ↑ vascular permeability, shock
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Anthrax Cutaneous anthrax (malignant pustule) Due to direct inoculatioin of skin from infected animal or its product Acquired – Industrial: leather workers, bone meal factories – Non-industrial: those work with animals
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Anthrax Pulmonary anthrax (wool sorter’s disease) – Inhaling spores in workers handle contaminated wool – Fever, respiratory distress, death – Mortality rate ↑ Gastrointestinal anthrax – Ingestion of spores, lethal
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Anthrax Diagnosis – Specimen: exudate from pustule, sputum – Gram stain – Culture Treatment Penicillin Prevention Vaccine workers at risk
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Plague Yersinia pestis: Gram-negative bacilli Animal reservoir: rodents e.g. rats; man get infected by bite of infected rat fleas 3 forms 1.Bubonic plague Painful enlargement of inguinal Lymph nodes MR ↑ (50%) due to haemorrhagic sepsis
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Plague 2. Pneumonic plague: inhalation of infected respiratory secretions, spread from one person to another, fatal 3. Septicaemic plague: primary or complication of pneumonic or bubonic plague Pathogenesis Capsule Somatic Antigen (V and W): resist phagocytosis
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Plague Diagnosis Specimen: bubo pus Gram stain Culture Treatment Tetracycline
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Pasteurella infection Pasteurella multocida: Gram-negative bacilli Reservoir: Upper respiratory tract of dogs, cats Bites or scratch from animal bite Infections: wound infection, septicemia Treatment Penicillin
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Erysipeloid Erysipelothrix rhusiopathiae: Gram-positive bacilli Reservoir: fish, birds, swine, pigs Wound infections during handling of meat, fish especially if skin abrasion
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Leptospirosis Leptospira species: spirochaetes Epidemiology Survive in stagnant water & wet soil for long time esp. if pH ↑ Animal reservoirs: – Small wild animals e.g. rodents – Domestic animals e.g. pigs, cattle, puppies Penetrate abraded & intact skin, conjunctiva, mucous membrane→ blood → kidneys, CNS
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Leptospirosis Transmitted to man by direct or indirect contact with animal urine Acquire infection – Wet occupation e.g. sugar cane field, rice field, farms, sewage workers – Leisure activities: swimming pools, play with infected pet Incubation period: 5-14 days 16 serogroups
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Leptospirosis Leptospira canicola serogroup: canicola fever: aseptic meningitis; (dogs, pigs) L. icterohaemorrhagiae serogroup: Weils’s disease: fever, jaundice, proteinuria, subconjunctival haemorrhage, hepatorenal failure; (rats) L. hebdomadis serogroup: (cattle) Diagnosis: serology: IgM, IgG Treatment: Penicillin
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Salmonellosis: Salmonella species Reservoir: chicken, turkey, cattle Food poisoning Campylobacter infection: Campylobacter species Reservoir: poultry, dogs Food poisoning
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Listeriosis Listeria monocytogenes: Gram-positive bacilli Reservoir: cattle, pigs, rodents, birds, fish Man get infection: direct contact with animals (stool), eat raw meat, soft cheese, infected milk Infections – Flue like illness: vets, farm workers, butchers – Meningo-encephalitis, sepsis: neonates, Immunosuppressed
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Listeriosis Diagnosis – Specimen: blood, CSF, vaginal swabs – Culture – Identification GPB β-haemolysis Motility at room temperature but not at 37°C Catalase positive Treatment: ampicillin
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Bovine tuberculosis Mycobacterium bovis Infect lungs of cattle; mammary glands (during chronic disease) Acquire infection: ingestion of unpasteurized milk Infections – Cervical adenitis – Mesenteric adenitis
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Q fever Coxiella burnettii Animal reservoir: Sheep, cattle Acquire infection – Handling infected animals or their products (infected placenta or meat) – Inhaling contaminated dust – Drinking infected unpasteurized milk
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Q fever Infections – Flue like illness – Pneumonia – Infective endocarditis – Hepatosplenomegaly Diagnosis: Serology Treatment Tetracycline
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Rabies Bullet-shape rhabdo RNA virus Virus present in saliva of infected animal Penetrate abrasion in skin or intact mucous membrane of animals and man → peripheral nerves → CNS (neurons: intracytoplamic inclusions - Negri bodies) Animals develop rabies: dogs, foxes, cats, cattle, monkeys Man get infection by bite from infected animal
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Rabies Incubation period 4-13 weeks (shorter if bitten on face, shoulder, upper limbs) Clinical Features Rabies: sore throat, fever, irritability, discomfort at site of bite Encephalomyelitis Excitement, convulsions, muscle spasm (hydrophobia), death due to heart or respiratory arrest
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Toxoplasmosis Epidemiology Toxoplasma gondii multiply in ileum of cat → oocysts in stool Acquire infection – Contact with cats or soil contaminated with oocyst – Ingestion of raw or under cooked meat of animals (intermediate host ) e.g. cattle, pigs
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Toxoplasmosis Clinical features Asymptomatic: healthy, febrile illness with LN+ Immunosuppressed: menengoencephalitis, myocarditis Congenital toxoplasmosis: chorioretinitis, cerebral calcification Diagnosis: Serology: IgM Treatment: pyrimethamine + sulfadiazine + folinic acid
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Lyme disease Borrelia burgdorferi Acquired by bite of tick (Ixodes spp.) after feeding on infected animal (deer) Europe, USA, China, Australia Manifestation: – Early localized: skin rash (2-3weeks) – Early disseminated: (weeks-months): LN +, arthritis, CNS, carditis – Late persistent : (1 st year): CNS, joint, skin lesions
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Lyme disease Diagnosis – Serology, ELISA – PCR – CSF serology Treatment: doxycycline or amoxicillin Prevention: avoid tick exposure
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