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Toxoplasma gondii, isospoa, cryptosporidium

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  1. 1. ClassificationClassification Phylum: Apicomplexa Class: Sporozoea Subclass: Coccidia Order: Eucoccidia Suborder: Eimeriina Genus: Toxoplasma Species: gondii
  2. 2. Toxoplasma gondiiToxoplasma gondii Worldwide Zoonotic parasite; Toxoplasma is an opportunistic pathogen. Infects animals, cattle, birds, rodents, pigs, and sheep. and humans. Causes the disease Toxoplasmosis. Toxoplasmosis is leading cause of abortion in sheep and goats. Intracellular parasite. Final host (Felidae family, cat) Intermediate host (mammals ) Toxoplasmosis 1. All parasite stages are infectious. 2. Risking group: Pregnant women, meat handlers (food preparation) or anyone who eats the raw meat
  3. 3. Definitive (final) host. Domestic cats, who pick up the organism from eating infected rodents. Asexual and sexual division is intracellular. Oocysts in feces. Intermediate host.. Asexual tissue cycle. Motile, disease producing phase = tachyzoites. Non-motile slow phase in tissue cyst = bradyzoites. Humans (Mammals) Cats (Mainly domestic and wild cats)
  4. 4. Toxoplasma gondiiToxoplasma gondii exists in three formsexists in three forms All parasite stages are infectiousAll parasite stages are infectious.. 1. Tachyzoites 2. Tissue cysts (bradyzoit) 3- Oocysts
  5. 5. Tachyzoite stageTachyzoite stage Rapidly growing stage observed in the early stage of infection. (Acute phase) habits in the body fluid. Crescent-shaped. One end is more pointed than the other subterminal placed nucleus. Asexual form. Multiplies by endodyogeny. It can infect phagocytic and non-phagocytic, cells.
  6. 6. BradyzoitesBradyzoites Are slow-growing stage inside the tissue cysts. Bradyzoites mark the chronic phase of infection. Bradyzoites are resistant to low pH and digestive enzymes during stomach passage. Protective cyst wall is finally dissolved and bradyzoites infect tissue and transform into tachyzoites. Bradyzoites are released in the intestine and are highly infective if ingested.
  7. 7. Oocysts in the feces of catOocysts in the feces of cat Cat ingests tissue cysts containing bradyzoites. Gametocytes develop in the small intestine. Sexual cycle produces the oocyst which is excreted in the feces. Oocysts appear in the cats feces 3-5 days after infection by cysts. Oocysts require oxygen and they sporulate in 1- 5 days.
  8. 8. The Oocyst The oocyst is noninfectious before sporulation. Unsporulated oocysts are subspherical to spherical. Sporulated oocysts are subspherical to ellipsoidal. Each oocyst has two ellipsoidal sporocysts. Each Sporocyst contains four sporozoites . Shedding occurs 3-5 days after ingestion of tissue cysts Sporulated oocyst remain infective for months .
  9. 9. Life cycle of T. gondii
  10. 10. Sources of infection : Contaminated water or food by oocysts Ingestion of tachyzoites and bradyzoites (cysts) in flesh of infected host. Undercooked meat. Mother to fetus. Organ transplant (rare). Blood transfusion (rare). Toxoplasma Transmission
  11. 11. Disease: ToxoplasmosisDisease: Toxoplasmosis A- Acquired toxoplasmosis(Mild lymphatic inflammation). B- Congenital toxoplasmosis: 1-Intracerebral calcification.
  12. 12. Congenital ToxoplasmosisCongenital Toxoplasmosis 2- Chorioretinitis . 3-Hydrocephaly. 4- Microcephaly . 5- Convulsions. 6- Mental retardation . 7- Cardiomegaly .
  13. 13. Prophylaxis 1- Individuals at risk, particularly pregnant women, children, and immunocompromised persons should avoid contact with cat and its feces. 2- Proper cooking of meal. 3- Proper washing of hands and washing of vegetables and fruits before eating. 4-Blood or blood products from seropositive persons 5- should not be given and screening for T. gondii antibody 6- should be done in all blood banks.
  14. 14. control It is difficult to control toxoplasmosis because of wide range of animal reservoirs. Currently, there is no effective vaccnine available for humans. A genetically engineered vaccine is under development for use in cats. Treatment Congenital infection is treated with pyrimethamine and sulfadiazine. For primary prophylaxis Trimethoprimsulfamethoxazole is the drug of choice
  15. 15. ClassificationClassification Phylum: Apicomplexa Class: Sporozoea Subclass: Coccidia Order: Eucoccidia Suborder: Eimeriina Genus:Isospora Species: belli
  16. 16. Morphology Oocysts of I. belli are elongatedovoid and measure 25 m 15 m. Each oocyst is surrounded by a thin smooth 2 layered cyst wall Immature oocyst seen in the feces of patients contain two sporoblasts. The oocysts mature outside the body.
  17. 17. On maturation, the sporoblast convert into sporocysts. Each sporocyst contain 4 crescentshaped sporozoites The sporulated oocyst containing 8 sporozoites is the infective stage of the parasite. A B Oocysts of Isospora belli. A. Immature cyst; B. Mature cyst
  18. 18. Life Cycle I. belli completes its life cycle in one host. Man gets infection by ingestion of food and water contaminated with sporulated oocyst. When a sporulated oocyst is swallowed, 8 sporozoites are released from the 2 sporocysts in the small intestine and invade the intestinal epithelial cells. In the epithelium, the sporozoites transform into trophozoites, which multiply asexually (schizogony) to produce a number of (merozoites). The merozoites invade adjacent epilhelial cells to repeat asexual cycle.
  19. 19. Some of the trophozoites undergo sexual cycle (gameto gony) in the cytoplasm of enterocytes and transform into macrogametocytes and microgametocytes. After fertilization, a zygote is formed, which secretes a cyst wall and develops into an immature oocyst. These immature oocysts are excreted with feces and mature in the soil. Incubation period: 14 days.
  20. 20. Life Cycle of Isospora belli
  21. 21. Clinical Features Infection is usually asymptomatic. Clinical illness includes abdominal discomfort, mild fever, diarrohea, and malabsorption. The diarrohea is usually watery and does not contain blood or pus and is selflimiting. However, protracted diarrohea, lasting for several years can be seen in immunocompromised persons, particularly in the human immunodefi ciency virus (HIV) infected.
  22. 22. Indirect evidence High fecal fat content. Presence of fatty acid crystals in stool. Presence of CharcotLeyden crystals in stool. Direct evidence It may be diffi cult to demonstrate the transparent oocyst in saline preparation of stool. Stool concentration techniques may be required when direct wet mount of stools are negative. The staining technique used are Modified ZiehlNeelsen stain or Kinyoun acid fast staining of stool smear. In these methods, pink colored acid fast large oocyst (>25 m) can be demonstrated. The stool smear can also be stained by auramine rhodamine and Giemsa stains. Laboratory Diagnosis 1-Stool Examination
  23. 23. 2- Duodenal Aspirates After repeatedly negative stood examinations, duodenal aspirate examination or enterotest can be performed to demonstrate oocyst. 3- Intestinal Biopsy Upper gastrointestinal endoscopy may provide biopsy specimens for demonstration of oocysts. 4-Others Eosinophilia, which is generally not seen with other enteric protozoan infections, is detectable in case of isosporoloasis
  24. 24. Treatment No treatment is indicated in self limiting infection in immunocompetent persons. Immunodefecient patients with diarrhea and excreting oocysts in the feces should be treated with cotrimoxazole (trimethoprimsulfamethoxazole) in a dose of 2 tablet, 4 times a day for 10 days followed by 2 tablets 2 times a day for 3 weeks. For patients intolerant to sulfonamides, pyrimethamine 5075 mg/day is given.Relapses can occur in persons with AIDS and necessitate maitainance therapy with cotrimoxazole 1 tablet thrice a week.
  25. 25. Classification Phylum: Apicomplexa Class: Sporozoea Subclass: Coccidia Order: Eucoccidia Suborder: Eimeriina Genus:Isospora Species: belli
  26. 26. Morphology The infective form of the parasite is oocyst. The oocyst is spherical or oval and measures about 5 m in diameter. Oocysts does not stain with iodine and is acid fast. The wall of the oocysts is thick, but in 20% cases, wall may be thin. These thin walled oocysts are responsible for autoinfection. Both thin walled and thick walled oocyst contain 4 crescent shaped. Oocyst can remain viable in the environment for long periods, as it is very hard and resistant to most disinfectants and temperature upto 60C. It can survive chlrorinated water, but sequential application of ozone and chlorine has been found effective in eliminating the cysts.
  27. 27. The parasite complete its life cycle, sexual and asexual phases in a single host (monoxenous) Suitable host: Man. Reservoirs: Man, cattle, cat, and dog. Mode of transmission: Man acquires infection by: Ingestion of food and water contaminated with feces containing oocysts Autoinfection. Infective form: Sporulated oocysts. The oocyst contains 4 sporozoites, which are released in the intestine.
  28. 28. Life Cycle
  29. 29. Pathogenicity and Clinical Features Clinical manifestations of c. parvum infection vary depending upon the immune status of the host. Infection in healthy immunocompetent persons may be asymptomatic or cause a selflimiting febrile illness, with watery diarrhea in conjunction with abodminal pain, nausea, and weight loss. It can also cause childhood and travellers diarrhea, as well as waterborne outbreaks.
  30. 30. In immunocompromised hosts, especially those with AIDS and CD4+ T cell counts below 100/uL, diarrhea can be chronic, persistent, and remarkably profuse, causing significant fl uid and electrolyte depletion, weight loss, emaciation, and abdominal pain. Stool volume may range from 1 to 25 L/day. Billary tract involvement can manifest as right upper quadrant pain, sclerosing cholangitis, or cholecystitis.
  31. 31. Laboratory Diagnosis Stool Examination Diagnosis is made by demonstration of the oocysts in feces. A direct wet mount reveals colorless, spherical oocyst of 45 m, containing large and small granule. The oocysts are diffi cult to visualize in unstained wet preparations. Modifi ed acid fast staining is the method of choice and by this method oocysts appear as red acidfast spheres, gainst a blue background . Yeast closely resembles oocysts of c. parvum in shape and size but can be differentiated by using acidfast stain, as they are not acidfast and appear blue in color. The staining can also be used for demonstration of oocysts in other specimens like sputum, bronchial washing, etc.
  32. 32. If oocysts load is less and cannot be demonstrated even after examination of 3 wet mounts of stool specimen, concentration techniques like Sheather's sugar floatation technique and zinc sulfate floatation technique can be applied. Fluroscent staining with auraminephenol or acridine orange has also been reported to be a useful technique. Definitive identification can be made by indirect immunofl uroscence microscopy using specific antibody.
  33. 33. Histopathological Examination: Cryptosporidia can also be identified by light and electron microscopy at the apical surface of intestinal epithelium from biopsy specimen of the small bowel (jejunum being the preferred site). Serodiagnosis: Antibody persists for at least an year and can be demonstrated by ELISA or immunofl uroscence. An ELISA for detection of cryptosporidium antigens in stools using monoclonal antibody has also been developed and is highly sensitive and specifi c. Molecular Diagnosis For seroepidemiological study, western blot technique is employed by using a 17KDA and 27KDA sporozoite antigen. PCR technique has also been applied to detect viable cysts
  34. 34. Supportive therapy with electrolytes and fluids and early antiretroviral therapy in AIDS patients.