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Dr.Waqas Nawaz

Dr.Waqas Nawaz
PMAS arid agriculture univrsity rawalpindi



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Zoonosis Zoonosis Presentation Transcript

  • ZOONOSIS:INTRODUCTION:The World Health Organization defines Zoonoses (Zoonosis,sing.) as "Those diseases and infections which are naturallytransmitted between vertebrate animals and man".CLASSIFICATION:Zoonoses can be classified in many ways:According to the mechanism of transmission Anthropozoonoses: Infections transmitted to man from lowervertebrates (ex: rabies, toxoplasmosis) Zooanthropozoonoses: Infections transmitted from man toanimals (ex: diphteria, amebiosis) Amphixenoses: Infections maintained in both man and lowervertebrates, and may be naturally transmitted in either direction(ex: Staphilococcus, mycobacteria)
  • CONTINUED…………..According to the life cycleDirect Zoonoses: Transmitted from infected vertebrate host to asusceptible vertebrate host by direct contact or by a mechanicalvector. No developmental change or propagation of the organismoccurs during the transmission (ex: Rabies, trichinosis, andbrucellosis)Cyclozoonoses: Requires more than one vertebrate host, but noinvertebrate host. (ex: Echinococcosis, human taeniasis andPentastoma infections)Metazoonoses: Agent multiplies, develops, or both in an invertebratehost before transmission to a vertebrate host is possible. (This meansthat a definite prepatent or incubation period must be completedbefore transmission.) (ex: Arboviruses, plague, and schistosomiasis)
  • CONTINUED…………..Saprozoonoses: To transmit these infections a non-animaldevelopment site or reservoir is required, such as foodplants, soil, or other organic material. (ex: larva migrans andsome of the mycotic diseases)According to the etiology (mostly used)Bacterial zoonoses: Botulism, tuberculosisViral zoonoses: Rabies, Hepatit A virusFungal zoonoses: Aspergillosis, actinomycosisProtosoal zoonoses: Anaplasmosis, babesiosis, malairaHelmintic zoonoses: Trichinosis, echinococosis, taeniasis
  • TOXOPLASMOSIS:Causative agent : Toxoplasma gondiiA coccidium belonging to phylumApicomplexaToxon = arc; Plastos = form. One stagein the life cycle is arc- shaped.The species name is derived from thehost in which the parasites was firstdescribed: Ctenodactylus gundi = smallAfrican rodent.HOST: mammals. Especially cats,food animals ,birds and humans.Mode of transmission: ingestion ofoocysts shed in feces of infected catsor found in raw meat and milk.
  • Pathology:Trachyzoite multiplication results in focal necrosis, the mostcharacteristic lesion of toxoplasmosis. Inflammation usuallyfollows necrosis. Pneumonitis is the predominant lesion infatal toxoplasmosis in cats and dogs; placental necrosis withwhite flecks or multiple white, chalky, necrotic nodules andassociated abortion predominate in sheep and goats.Histologcially, this necrosis is confined to the cotyledonswhere individual and small group of tachyzoites are oftendifficult to recognize among degenerating host cells.Encephalomyelitis is the predominant lesion in sheep.Diagnosis:Diagnosis of Toxoplasma is performed at postmortem byidentification of organisms in infected tissue. Diagnosis inlive animals is aided by serologic tests and in cat by fecalexamination.
  • Prevention and Control:The following preventative measures apply to all persons, butbecause toxoplasmosis is most severe in the prenatal period, theyshould be emphasized for pregnant women and for young children.1. Avoid contamination with oocysts from cat feces by: a. Feeding cats dry, canned or thorougly cooked food b. Preventing cats from hunting birds and rodents c. Emptying litter boxes daily, before oocysts sporulate d. Wearing gloves or thoroughly washing hands after working in the garden or with soil, and before eating or touching the face e. Covering children’s sandboxes when not in use f. Preventing aerosols in the laboratory during centrifugation of potentially infected biological samples g. Boiling drinking water from streams, ponds, or lakes frequented by cats2. Avoid ingestion of tissue cysts by cooking meat to over 660 C andwashing hands after handling raw meat.
  • The following preventative measures apply to farms andother animal-rearing facilities. Avoid contamination offeed or water with oocysts in cat feces by:1. Using rodenticides and traps to prevent cats fromhunting rodents2. covering, closing or locking feed-storage facilities toprevent cats from entering and defecating3. Promptly removing cat feces from building stalls orcages; and flushing, burning, or burying them to destroyoocysts4. Providing adequate dry, canned, or thoroughlycooked food and separate water to prevent cats fromsharing facilities used by other animals.
  • SARCOCYSTIS :Causative agent: Sarcosystissuihominis. S. hominisA coccidium belonging to phylumApicomplexaHumans may become infected by twospecies, S.hominis and S.suishominisHOST: man, cattle and swineMode of transmission: ingestion ofraw pork or beef; ingestion of feces.Ingestion of raw beef ; ingestion offeces.
  • PathologySome species of Sarcocystis are pathogenic to the herbivore intermediatehost. Acute lesions characterized by hemorrhage, edema, and necrosisare associated with the maturation of second generation meronts.Macroscopic lesions observed postmortem may include generalizedserous atrophy of fat, excessive yellowish fluid in all body cavities, wateryblood, petechical hemorrhage in the heart and pericardium, serosa of thegastrointestinal tract and urinary bladder, edema and hemorrhage oflymph nodes, and alternate pale and dark striping or mottling of skeletalmuscles. Microscopically, hemorrhage may be seen in all organs, andmononuclear cell infiltration into the perivascular tissues of the hear,skeletal muscles, lung, liver, and kidney may be mild to severe.Regenerative changes are most often associated with the myocardium.Chronic lesions charactgerized by muscle atrophy and myositis areassociated with mature saccocysts. Specific macroscopic lesions may notalways be seen postmortem. Microscopic lesions may include myositisand myocarditis. Most definitive hosts are clinically unaffected bySarcocystis infection.
  • Diagnosis:EXAMINATION OF fecesSerologic testsMeat inspectionCONTROL:Cattle or swine should be prevented from ingestinghuman feces and humans should avoid eating rawor undercooked meat.