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Zoonoses
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Zoonoses are disease and infections of animals
Causative agents are transmitted between animals and humans
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Origin – Not exactly …! Who knows..!
Zoonotic diseases have been known since antiquity Bubonic plague and rabies were known since biblical times More than 150 zoonoses have been recognized In recent years several new zoonotic diseases have emerged E.g. KFD, Monkey Pox etc., Apart from morbidity and mortality they cause great economic losses Particularly in animals, meat, milk and other foods and products of animal origin
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As usual…! Developing countries suffer much severe losses than developed countries Less well developed public health and veterinary services and partly because of their unfavourable climatic and environmental conditions Zoonoses and human health are matters of particular concern in India Because nearly 80% of India’s population is rural and live in close contact with domestic animals and often not far from wild ones
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Definition Zoonoses have been defined “Those disease and infections (the agents of) which are naturally transmitted between (other) verterbrate animals and man” Zoonoses have been classified in terms of their reservoir hosts, whether these are men or lower vertebrate animals…
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Classified in terms of their reservoir host...
Anthropo-zoonoses: Infections transmitted to man from lower vertebrate animal, eg. Rabies Zooanthroponoses: Infections transmitted from man to lower vertebrate animals However these terms have also been used interchangeably for all diseases found in both animals and man, eg. TB
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Amphixeonoses: Has been used for infections maintained in both man and lower vertebrate animals that may be transmitted in either direction, eg. Staphylococcal infections Euzoonoses Diseases in which humans are an obligatory host of the agent, eg. Taenia solium and Taenia saginata
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Classification based upon the type of life cycle of the infecting organism Four categories:
1.Direct Zoonoses: Transmitted from an infected vertebrate host to a susceptible vertebrate host By direct contact, by fomite or by mechanical vector Agent itself undergoes little (or) no propagative changes and no essential developmental change during transmission Examples: Rabies, Trichinosis and Brucellosis
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2. Cyclo – zoonoses: Require more than one vertebrate host species
No invertebrate host, in order to complete the developmental cycle of the agent Ex: Human taeniases, echinococcosis and pentastomid infections
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3.Meta – Zoonoses Transmitted biologically by invertebrate vectors
Invertebrate- agent multiplies (or) develops or both and there is always an extrinsic incubation (prepatent) period before transmission to another vertebrate host is possible Ex: Arbovirus, Plague, Schistosomiasis
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4.Sapro-zoonoses: Have both vertebrate host and a non-animal developmental site or reservoir Organic matter (including food), soil and plants are considered to be non-animal Ex: Various forms of larva migrants and some of the mycoses
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Common Zoonotic Diseases
Bacteria Rickettsia Virus Parasite Fungus Anthrax Scrub typhus Rabies Taeniasis Plague Murine typhus Yellow fever Echinococcosis Brucellosis Tick typhus Japanese encephalitis Leishmaniasis Zoonotic dermatophytes Leptospirosis Q fever KFD Toxoplasmosis Salmonellosis Chikungunya
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Collection of specimens:
Specimen are collected according to the site of lesion Laboratory diagnosis tests for bacterial, rickettsial, parasitic and fungal zoonosis Laboratory diagnosis: Lab diagnosis is important for the diagnosis of zoonoses In humans and animals this is based on Isolation Serology Autopsy
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BACTERIAL Zoonotic Diseases
Sample Microscopy Culture Serology Others Cutaneous anthrax Fluid from eschar Gram positive bacilli NA –Medusa head Ascoli’s thermoprecipitin Lysis by gammaphage Pulomonary anthrax Sputum stool BAP-String of pearls ELISA Direct fluorescence antibody test Intestinal anthrax McFadyean’s reaction Gelatin stab- Inverted fir tree Acute brucellosis (Undulent fever) Blood Gram negative coccobacilli Casteneda method Std agglutination test ELISA, CFT SKIN test
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BACTERIAL Zoonotic Diseases
Sample Microscopy Culture Serology Others Bubonic plague Fluid from buboes sputum Gram negative bacilli, bipolar staining NA, BAP Passive hemagglutination PCR Pneumonic plague Blood Safety pin appearance Chee broth (Stalactitie growth) Salmonellosis Stool Food Gram negative bacilli MacConkey agar, wilson and blair medium Widal test
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BACTERIAL Zoonotic Diseases
Sample Microscopy Culture Serology Others Leptospirosis Blood Urine Dark ground microscope, spirochete Karthof’s medium Stuart’s medium Fletcher’s medium Microscopic agglutination test Tuberculosis (M.bovis) Sputum Acid fast bacilli L J medium
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Laboratory procedures for Viral Zoonoses:
Disease Sample Microscopy Culture Serology Rabies Antemortem –corneal impression smear, Skin biopsy: Saliva Postmartem-brain Immuno-fluorescence Negri bodies Tissue culture (WI 38, BHK 21) Yellow fever Blood Yolk sac of chick embryo Hemagglutination inhibition Japanese Encephalitis CSF Intracerebral inoculation CFT KFD Chickungunya ELISA
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Laboratory procedures for Parasitic Zoonoses:
Disease Sample Microscopy Serology Taenia Stool Egg ELISA Echinococcus Hemagglutination Indirect fluorescent antibody Leishmania Blood Peripheral blood, Amastigote (LD bodies) Aldehyde test Antimony test CFT
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Laboratory procedures for Fungal Zoonoses:
Disease Sample Microscopy Culture Zoophilic dermatophytes KOH preparation SDA Microsporumcanis Skin scraping Trichophyton verrucosum Hair clipping T.equinum Nail clipping
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RICKETTSIAL ZOONOSES Rickettsial diseases 1. Typhus group Agent
Vectors reservoirs a. Epidemic typhus R. prowazekii Louse Humans b. Murine typhus R. typhi Flea Rodents c. Scrub typhus R. tsutsugamushi mite* 2. Spotted fever group a. Indian tick typhus R. conorii Tick* Rodents, dogs b. Rocky mountain spotted fever R. rickettsii Rodents, dogs c. Rickettsial pox R. akari Mite* Mice 3. Others a. Q fever C. burnetii Nil Cattle, sheep, goats b. Trench fever Rochalimaea quirttana
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Laboratory procedures for Rickettsial zoonoses:
Disease Sample Culture Serology Scrub typhus Blood Yolk sac of chick embryo Weil-Felix test Murine typhus Indian Tick typhus CFT
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