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2013-12-14 15:36:36
parasitology biology

parasitology notes
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  1. Three groups in phylum Apicomplexa
    Gregarines, Coccidia, Haemogregorines
  2. Three phases of Apicomplexan reproduction
    Schizogony, Gametogony, Sporogony
  3. Three life cycle stages in Schizogony phase
    Trophozoite, schizont, segmenter
  4. Which reproductive phase is a Trophozoite in?
  5. Which reproductive phase is a Schizont in?
  6. Which reproductive phase is a Segmenter in?
  7. Which reproductive phase is a Gametocyte in?
  8. Which reproductive phase is a Gamete in?
  9. Which reproductive phase is an Ookinete in?
  10. Which reproductive phase is an Oocyst in?
  11. Which reproductive phase is a Sporocyst in?
  12. Which reproductive phase is a Sporont in?
  13. Three life cycle stages in Gametogony phase
    ookinete, gametes, gametocytes
  14. Three life cycle stages in Sporogony phase
    Oocyst, sporocyst, sporont
  15. What are the simplest Apicomplexans?
  16. only species of Gergarines we covered?
    Lankerista culicis
  17. Host and body area of Lankesteria culicis?
    Arthropods, alimentary canal
  18. 5 characteristics of Coccidians (host, body area, asexual and sexual reproduction, oocyst features)
    • 1. All classes of vertebrates
    • 2. intracellular, mostly intestinal tract
    • 3. asexual reproduction by schizogony and sporogony
    • 4. sexual reproduction by gametogony
    • 5. sporozoites develop in sporocysts in an oocyst
  19. What type of Apicomplexan lives in vertebrates' intestinal tract, undergoes schizogony, sporogony, and gametogony, and has sporocysts in an oocyst containing sporozoites?
  20. Two types of Coccidians
    Eimerians and Isosporans
  21. What group is Eimeria tenella in?
    Apicomplexa - Coccidia
  22. Describe Eimeria tenella's life cycle.
    • 1. Oocyst forms a zygote which undergoes sporogony to form many sporozoites.
    • 2. After being ingested by the host (birds, chickens), it undergoes two stages of schizogony (trophozoite -> schizont) to form merozoites
    • 3. Merozoites undergo gametogony, to form sporozoites within oocysts
  23. Where in the host does Eimeria tenella develop?
    Sporozoites invade epithelial (villi) cells in the caecum of a bird, undergo schizogony to form merozoites (that then go on to reproduce and form schizonts)
  24. How many second generation merozoites is one oocyst of Eimeria tenella capable of producing in a host?
    a lot - 2.52 million, enough to self-limit the population in the host
  25. Name 4 genera in the Isopora group of Coccidians.
    Isospora, Toxoplasma, Sarcocystis, Cryptosporidium
  26. What group is the genus Isospora in?
    Apicomplexa - Coccidia - Isospora
  27. What group is the genus Toxoplasma in?
    Apicomplexa - Coccidia - Isospora
  28. What group is the genus Sarcocystis in?
    Apicomplexa - Coccidia - Isospora
  29. What group is the genus Cryptosporidium in?
    Apicomplexa - Coccidia - Isospora
  30. What is the one Isospora species that is found in humans? What disease does it cause?
    Isospora belli - Human coccidiosis
  31. Describe the Isospora belli life cycle.
    • 1. Schizogony occurs in epithelium of distal duedenum and proximal jejunum. Several generations of merozoites is formed over a week.
    • 2. Gametogony begins, continues for 2 weeks
    • 3. Oocysts with 2 sporocysts each are passed in feces
  32. Where is Isospora belli found, and what are its hosts?
    In tropical regions - human hosts, may be carried by dogs
  33. What pathology does Isospora belli cause in its host?
    Severe diarrhea over several months to 15 years, weight loss, abdominal colic, fever, hypereosinophilia, nausea, vomiting.
  34. What group is Toxoplasma gondii in?
    Apicomplexa - Coccidia - Isospora
  35. What is an alternate name for Toxoplasma gondii?
    Isospora cati
  36. Describe the life cycle of Toxoplasma gondii.
    • 1. Oocyst with 2 sporocysts (with 4 sporozoites each) ingested by intermediate host (humans, other animals)
    • 2. Asexual reproduction takes place (sporogony)
    • 3. Sporocyst infects definitive host (cat), merozoites released
    • 4. Merozoites infect intestine epithelial cell undergoes schizogony, replicate themselves
    • 5. tachyzoites convert into bradyzoites, tissue cysts
    • 6. oocyst passed in feces
  37. What happens when sporozoites of Toxoplasma gondii infect a developing fetus?
    Merozoites form a zoitocyst (tissue cyst) in the brain tissue, resulting in neurological defects
  38. What are 2 ways to prevent infection by Toxoplasma gondii?
    avoid rare beef products, hard freeze meats to destroy cysts
  39. What are the two Sarcocystis species found in humans?
    S. hominis, S. suihominis
  40. Describe the life cycle of Sarcocystis
    • heteroxenous
    • Sporocysts infect herbivorous intermediate host, form cysts in tissues that contain schizonts
    • Carnivorous definitive host ingests cysts, sexually reproduces to form oocysts
  41. What symptoms does Sarcocystis cause in humans?
    No symptoms, sporocysts not passed
  42. What is the prepatent period of Sarcocystis?
    18-39 days
  43. What symptoms does Cyclospora cayetanensis cause?
    cycling or relapsing diarrhea, may alternate with constipation. Also fatigue, cramps, weight loss, vomiting, low grade fever
  44. How is Cyclospora cayetamensis thought to be transmitted?
    Oocysts on contaminated fruit (raspberries)
  45. What group is Cyclospora cayetamensis in?
    Apicomplexa - Coccidia - Isospora
  46. What group is Cryptosporidium parvum in?
    Apicomplexa - Coccidia - Isospora
  47. Describe the life cycle of Cryptosporidium parvum in the definitive host
    Trophozoites live under the surface of intestinal or respiratory cells. Oocysts are released into fecal material
  48. What are the symptoms of an infection by Cryptosporidium parvum?
    severe diarrhea for several months, 6-25 stools per day, 1-17 liter per day stool volume. Very common and deadly for AIDS patients
  49. What group is pneumocystis carinii in?
    Apicomplexa - Coccidia - Isospora
  50. Where does Pneumocystis carinii infect, and what are the symptoms?
    fungus-like infection of interstitium of lungs, but not alveoli - causes pneumonia, filling alveoli with foamy exudates, fever, cough, rapid breathing, blue skin around mouth and eyes, asphyxiation. Fatal if untreated.
  51. What genus is responsible for causing malaria?
  52. What group is Plasmodium in?
    Apicomplexa - Haemogregarines
  53. What is the "ring-stage" of a Plasmodium?
    Trophozoite - found in infected white blood cell
  54. What is the stage of a Plasmodium when it is introduced into the bloodstream via mosquito?
    Sporozoites - Exoerythrocytic phase, before RBCs are infected
  55. What is recrudescence?
    When merozoites (of Plasmodium) break out of the liver to infect the bloodstream in the erythrocytic phase, may recur over time
  56. What are the 4 species of Plasmodium we covered?
    • P. vivax - "benign" malaria, may persist for many years
    • P. falciparum - "malignant" malaria, acute symptoms over 4-5 days, very fatal
    • P. malariae - rarer. usually lasts a few weeks, but may stay for years. Ziemann's stippling
    • P. ovale - rarer, latency of 4 years, cells have James' or Schuffner's dots.
  57. Plasmodium vivax:
    1. How often do paroxysms occur?
    2. How many merozoites in a schizont?
    3. How long do schizonts persist?
    4. What do infected blood cells look like?
    • 1. 48 hours
    • 2. 15-20 merozoites, usually 16
    • 3. many (40) years
    • 4. RBCs enlarged with Schuffner's dots, rapid increase in infected cells
  58. Plasmodium falciparum:
    1. How often do paroxysms occur?
    2. How many merozoites in a schizont?
    3. How long do schizonts persist?
    4. What do infected blood cells look like?
    • 1. 36-48 hours
    • 2. 8-32 merozoites, average 16
    • 3. 5-6 days, then move to blood
    • 4. RBCs with accole-applique rings, Maurer's clefts (debris). Microgametocytes are banana-shaped
  59. Plasmodium malariae:
    1. How often do paroxysms occur?
    2. How many merozoites in a schizont?
    3. How long do schizonts persist?
    4. What do infected blood cells look like?
    • 1. 72 hours
    • 2. 6-12 merozoites, average 8 - arranged in rosette pattern
    • 3. Exoerythrocytic phase lasts 2 weeks to 40 years
    • 4. Ziemann's stippling
  60. Plasmodium ovale:
    1. How often do paroxysms occur?
    2. How long do schizonts persist?
    3. What do infected blood cells look like?
    • 1. 49-50 hours
    • 2. up to 4 years
    • 3. James' dots or Schuffner's dots
  61. Briefly describe the malaria life cycle.
    • 1. Mosquito transfers sporozoite to human bloodstream
    • 2. Sporozoite moves to liver, undergoes schizogony (replication) to produce many merozoites in a schizont
    • 3. Merozoites (trophozoites) infect red blood cells and undergo schizogony to make more merozoites
    • 4. Some merozoites form gametocytes in RBCs
    • 5. In mosquito, gametocytes fuse to form ookinete (mobile zygote)
    • 6. Ookinetes develop into new sporozoites
  62. What happens to the spleen during a malaria infection?
    Plasmodia accumulate, spleen becomes inflamed and enlarged. Initially appears soft, but hard in chronic infections. Color is gray to dark brown, or black in chronic cases. Capillaries filled with infected RBCs, free plasmodia, pigment, and infected macrophages
  63. What is the frequency of spelomegaly in children in holoendemic areas?
    over 75%
  64. What is the frequency of spelomegaly in children in hyperendemic areas?
  65. What is the frequency of spelomegaly in children in mesoendemic areas?
  66. What is the frequency of spelomegaly in children in hypoendemic areas?
    less than 10%
  67. In a human malaria infection, where can sporozoites be found?
    Bloodstream - moving to liver
  68. In a human malaria infection, where does schizogony take place?
    In the liver - sporozoites replicate to become merozoites
  69. In a human malaria infection, where can merozoites be found?
    In liver, bloodstream or in infected RBCs
  70. In a human malaria infection, where can trophozoites be found?
    Liver, bloodstream, going to infect RBCs
  71. In a human malaria infection, where can gametocytes be found?
    In infected RBCs
  72. In a human malaria infection, where can ookinetes be found?
    In the mosquito
  73. What is responsible for paroxysms?
    Hemozoin released when malaria-infected RBCs burst to release merozoites.
  74. What happens when malaria infects the brain?
    • Cerebral malaria - (10% of cases) Gray matter darkens with infected RBCs, loss of oxygen to brain
    • Progressive headache, coma, psychosis, convulsions (esp in children), death
  75. How do falciparum-malaria infected RBCs change when infected by a trophozoite?
    Waste products from trophozoite growth accumulate, "knobs" form on cells that bind glycoproteins - causing infected cells to clump together and block capillaries
  76. What is Algid malaria?
    • Form of malaria pathology. Rapid development of shock - circulatory collapse, low blood pressure. Skin becomes cold and clammy, peripheral veins constricted.
    • Secondary bacterial infection of blood (septicemia), toxemia and gastrointestinal hemorrhage
  77. What is Blackwater Fever?
    Form of malaria pathology. Massive lysis of RBCs - high levels of hemoglobin and breakdown products in blood and urine due to renal insufficiency
  78. How long to sporozoites develop in an Anopheles mosquito:
    1. P. vivax
    2. P. falciparum
    3. P. malariae
    • 1. 16 days
    • 2. 22 days
    • 3. 30-35 days
  79. What is the term for malaria cases contracted locally at an endemic site?
  80. Where do autochthonous malaria infections occur?
    Local area where malaria is endemic