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  2. 2. Human Toxoplasmosis <ul><li>Toxoplasmosis is a zoonotic disease </li></ul><ul><li>Caused by Coccidian protozoan Toxoplasma gondii </li></ul><ul><li>Infectes a wide range of animals, birds but does not appear to cause disease in them </li></ul>
  3. 3. Toxoplasmosis (TOX-o-plaz-MO-sis ) <ul><li>A disease of the blood and lymphatic system. </li></ul><ul><li>Cats are a critical part of the life cycle. </li></ul><ul><li>It is usually acquired by eating undercooked meats but can also be acquired by contact with cat feces. </li></ul><ul><li>Primary problem is a congenital infection of fetus, resulting in either a stillbirth or a child with severe brain damage or vision problems. </li></ul>
  4. 4. Toxoplasmosis <ul><li>The normal final host is cat and relatives in the family Felidae, only hosts in which the Oocyst – producing sexual stage of Toxoplasma can develop </li></ul>
  5. 5. By feeding on Mice brains Cats can get Infected
  6. 6. Events on Rat to Cat Transmission
  7. 7. Spread from Rats – Cats to Humans
  8. 8. Spread of Toxoplasmosis
  9. 9. Development in Cat <ul><li>Organisms ( either sporozoites from Oocysts or Bradyzoites from tisse cysts ) invade the muscle cells of cats samll intestine where they from Schizonts or Gametocytes after sexual fusion of Gametes,oocysts develop exit from the host cells into the gut lumen of the cat and pass out via feces </li></ul>
  10. 10. Structure of Sporozoites <ul><li>In each Oocysts two sporocysts form and in about 48 hours four sporozoites form within sporocyst. </li></ul><ul><li>The Oocyst with its each Sporozoites when ingested can either repeat its sexual cycle in a Cat </li></ul>
  11. 11. Events on Development in man <ul><li>When man ingests Oocysts with eight Sporozoites excreted in Cats feces, can establish an infection and reproduces Asexually </li></ul><ul><li>In humans Oocysts open in duodenum and releases eight Sporozoites which pass through the gut wall </li></ul><ul><li>Circulate in body and invade various cells </li></ul>
  12. 12. Cycles of Development in Man
  13. 13. Invasion of Lymphnodes lead to chronic infections <ul><li>Sporozoites invade various cells especially macrophages where they from Trophozoites further multiply break out and spread the infection to lymphnodes and other organs </li></ul><ul><li>The rapidly multiplying Crescentric cell (Tachyzoites ) initiate the acute stage of disease </li></ul>
  14. 14. Invade Organs Brain involvement carries higher Morbidity and Mortality <ul><li>In futher development they penetrate new cells especially Eye and Brain. </li></ul><ul><li>Further development slows down in these organs called ad Bradyzoites to form a quiescent tissue cysts </li></ul><ul><li>The event lead to chronic stage of disease </li></ul>
  15. 15. Fate of Tissue Cysts Showing multiple tissue cysts <ul><li>The tissue cysts are infective when ingested by cats or eaten by other animals, where tissue cysts are formed </li></ul><ul><li>In man it dead end of disease </li></ul>
  16. 16. Implications on Human Health <ul><li>In Humans produces </li></ul><ul><li>1 Congenital Toxoplasmosis </li></ul><ul><li>2 Post natal Toxoplasmosis </li></ul>
  17. 17. Many Humans at risk with Toxoplasmosis
  18. 18. Congenital Toxoplasmosis <ul><li>Congenital infection develop in fetus only when non immune mothers are infected during pregnancy </li></ul><ul><li>Post natal Toxoplasmosis is less severe. </li></ul>
  19. 19. Other Human Infections Early detection reduce Morbidity <ul><li>Toxoplasmosis produces severe Human infections in patient with </li></ul><ul><li>AIDS </li></ul><ul><li>The chronic infection is altered to Acute manifestations </li></ul>
  20. 20. Toxoplasmosis - Immunosupressed <ul><li>Varying degrees of disease may occur in Immunosupressed indivudals results in </li></ul><ul><li>Retinitis </li></ul><ul><li>Chorioretinits </li></ul><ul><li>Pneumonias </li></ul><ul><li>Other non specific manifestions </li></ul>
  21. 21. Toxoplasmosis - Retinitis
  22. 22. Morphology and Identification of Toxoplasmosis <ul><li>The Trophozoites are boat shaped </li></ul><ul><li>Thin walled cell </li></ul><ul><li>Size is 4–7 x2-4 microns lie within tissue cells </li></ul><ul><li>But appear larger when outside the tissue cell </li></ul><ul><li>Stain lightly with Giemsa’s stain </li></ul><ul><li>True cysts contain many thousands of spore like Bradyzoites </li></ul>
  23. 23. Culturing Toxoplasma <ul><li>Toxoplasma gondii may be cultured in the presence of living cells in the culture tissues or eggs </li></ul><ul><li>Organisms can be seen intracellularly or extracellularly </li></ul>
  24. 24. Pathogenesis <ul><li>The Tacyzoites have predilection for parenchymal cells and Reticulo endothelial system and directly destroys the cells. </li></ul><ul><li>Humans are relatively resistant to infection </li></ul><ul><li>But low grade infection of lymph node persists </li></ul><ul><li>When tissue cysts ruptures – releases number of Bradyzoites </li></ul><ul><li>Local hypersensitivity reaction may cause inflammation. </li></ul><ul><li>Causes blocking of blood vessels </li></ul><ul><li>Causes death of cells near damaged area </li></ul>
  25. 25. Congenital Infection <ul><li>Lead to </li></ul><ul><li>Still Birth </li></ul><ul><li>Chorioretinits </li></ul><ul><li>Intracellular calcification </li></ul><ul><li>Psychomotor disturbances </li></ul><ul><li>Hydrocephaly </li></ul><ul><li>Microcephaly </li></ul><ul><li>Prenatal toxoplasmosis may manifest with blindness apart from congenital defects </li></ul>
  26. 26. Toxoplasmosis in Pregnancy <ul><li>In 1 st Trimester </li></ul><ul><li>May lead to still birth </li></ul><ul><li>Major central nervous system anomalies </li></ul><ul><li>In 2 nd Trimester </li></ul><ul><li>Less severe complications </li></ul><ul><li>Birth Anomalies still common </li></ul>
  27. 27. Babies infected with congenital Toxoplasmosis manifest with <ul><li>brain damage </li></ul><ul><li>enlarged spleen and liver </li></ul><ul><li>eye damage </li></ul><ul><li>jaundice </li></ul><ul><li>poor motor coordination </li></ul><ul><li>unusually small head </li></ul><ul><li>rash </li></ul>
  28. 28. Late Anomalies in Toxoplasmosis <ul><li>Clinical manifestation in infected fetus may be delayed until long after birth </li></ul><ul><li>Even may present during early childhood. </li></ul><ul><li>Neurological problems of learning difficulties may be caused by long delayed effects of late prenatal infection. </li></ul>
  29. 29. Diagnosis of Toxoplasmosis <ul><li>Desired specimens, </li></ul><ul><li>Blood ( Buffy coat of heparinised sample ) </li></ul><ul><li>Sputum </li></ul><ul><li>CSF </li></ul><ul><li>Exudates </li></ul><ul><li>Lymphnodes </li></ul><ul><li>Tonsil tissues </li></ul><ul><li>Striated muscle biopsy </li></ul><ul><li>Ventricular fluid in Neonates </li></ul>
  30. 30. Microscopic Examination of Tissues <ul><li>Smears and sections stained with Giemsa’s stain </li></ul><ul><li>Periodic acid Schiff method preferred </li></ul><ul><li>The densely packed cysts seen in the brain or other parts of nervous system suggest chronic infection </li></ul>
  31. 31. Serology <ul><li>Sabin Feldman dye </li></ul><ul><li>test </li></ul><ul><li>based on principle that Antibodies to Toxoplasma appear in 2-3 weeks that will render the membrane of the laboratory cultured living T.gondii impermeable to Alkaline methylene blue ,So the organism are unstained in the presence of serum with antibodies </li></ul>
  32. 32. Newer Methods in Diagnosis <ul><li>Immuno florescent assay method. </li></ul><ul><li>ELISA for IgM and IgG detection </li></ul><ul><li>PCR </li></ul><ul><li>Frankel’s intracutaneous test useful for epidemiologcal purpose </li></ul>
  33. 33. Immunity <ul><li>Acquired immunity in women is particularly protective to the fetus. </li></ul><ul><li>In Immunosupressed and AIDS patients changes the host resitance and causes chronic infection becomes fulminating acute Toxoplasmosis </li></ul>
  34. 34. Treatment <ul><li>Combination of Pyramethamine and Sulphadiazine or Trisulfapyramidines </li></ul><ul><li>Other alternative Drugs </li></ul><ul><li>Spiramycin </li></ul><ul><li>Clindamycin </li></ul><ul><li>Trimethoprim – Sulphmethoxazole </li></ul><ul><li>In pregnancy – Spriamycin is recommended drug </li></ul>
  35. 35. Control of Toxoplasmosis <ul><li>Avoidance of human contact with Cat feces is highly important measure. </li></ul><ul><li>Changing of Cat litter and safe disposal can prevent transmision </li></ul><ul><li>Pregnant women should avoid contact with kittens </li></ul>
  36. 36. Screening of pregnant women <ul><li>Periodic screening of pregnant women with high risk for IgG and IgM antibodies to Toxoplasmosis is recommended </li></ul>
  37. 37. Care of the Meat <ul><li>Avoid eating raw or undercooked meat. </li></ul><ul><li>Freezing < -20 0 c </li></ul><ul><li>Heating at 50 0 c for 4-6 minutes destroys the cysts and sterilizes the meat. </li></ul>
  38. 38. Created for Health Awareness on Toxoplasmosis Dr.T.V.Rao MD Email [email_address]