1. The Amebae – Chapter 7 Old taxonomy: Phylum Sarcomastigophora Subphylum Sarcodina New taxonomy: Phylum Sarcodina or Super-Group Amebozoa Amebae move and feed through the ______________________ _____________________________ Some amebae may have a __________________________as well in their life cycle (indicates evolution from the Mastigophora). Most amebae are free-living organisms in soil and water. A few species have become parasitic in vertebrates and may cause dangerous diseases in their hosts.

2. 2 Groups of Parasitic Amebae ____________________parasites – can only exist as parasites - amebae in the family Entamoebidae - occur in the digestive tracts of vertebrates ____________________parasites – free-living soil and water amebae that can become parasitic if they enter vertebrate tissues

4. Entamoeba histolytica DISTRIBUTION - Parasite has worldwide distribution but is most common in the ___________________________________of the world - it is estimated that up to 500 million people may be affected - may cause up to 100,000 deaths each year - a number of outbreaks have resulted from a breakdown in sanitation Outbreak in 1933 World's Fair in Chicago caused by defective plumbing (cross connections between water lines and sewer lines) caused over 1000 cases of amebiasis resulting in 58 deaths PREVALENCE: _________% in Canada and Alaska _________% in U.S. (________% in Wisconsin in 1987) _________% in the tropics

6. Entamoeba histolytica trophozoites

7. Entamoeba histolytica – 2 stages: 2. CYST - encystment is stimulated by ________________________________ - trophozoite condenses into a sphere - the _________________________ - precyst secretes cyst wall to form the round cyst - 10 to 20  m in diameter - nuclear division begins after encystment: _______________ cyst  ________________cyst  _________________ or mature cyst

9. Entamoeba histolytica cysts uninucleate cyst binucleate cyst

10. Entamoeba histolytica mature cysts quadrinucleate or mature cysts – diagnostic in feces

11. Entamoeba histolytica life cycle DIAGNOSTIC STAGE: INFECTIVE STAGE: Cysts are susceptible to heat (above 40 C.), freezing (below –5 C.), and drying Cysts remain viable in moist environment for 1 month

12. Entamoeba histolytica life cycle Infection occurs when infective cysts are ingested in food or water that has been contaminated with human feces. Thus, this parasite is transmitted from human to human via fecal contamination and is an ______________________

13. Entamoeba histolytica life cycle Common source of infection is from the use of ________________________ - _____________________ used to fertilize vegetables

14. Entamoeba histolytica life cycle . Excystment: Metacystic ameba undergoes multiple fission to form _____ trophozoites. Trophozoites move into the large intestine and invade the mucosa.

15. Entamoeba histolytica pathology 1. COLONIZATION OF THE LARGE INTESTINE flask-shaped lesions: proteolytic enzymes : Symptoms: Ulcers may form sinuses and extend into the submucosa

16. Entamoeba histolytica pathology 1. COLONIZATION OF THE LARGE INTESTINE primary ulcer: Mucosa submucosa

17. Entamoeba histolytica pathology 2. COMPLICATIONS IN LARGE INTESTINE A. Ulcers extend deep into the _______________________________ and may extend completely through the large intestine causing a _______________________________ _______________________________________ (bacterial infection in the abdominal cavity) - this complication results in a high percentage of fatalities B. Trophozoites invade the blood vessels of the submucosa and metastasize to ectopic sites

18. Entamoeba histolytica pathology 3. EXTRA-INTESTINAL LESIONS occur in 3 ECTOPIC SITES A. HEPATIC AMEBIASIS Trophozoites in submucosa are carried by hepatic portal vein to the liver. Trophozoites digest away liver tissue forming _________________________ - some to size of grapefruit B. PULMONARY AMEBIASIS Liver abscess ruptures Trophozoites digest through the ______________________into the lungs to form a______________________________ C. CEREBRAL AMEBIASIS Trophozoites in bloodstream reach ________________________& form fatal _________________________

19. Liver abscess Diagram of pathology from text on page 112 Shows movement of trophozoites from large intestine to lungs via hepatic portal vein

21. Non-pathogenic Amebae We will examine 3 species in laboratory: Entamoeba coli Very common parasite in the ______________________________________________________________________________________________________ Often co-exists with E. histolytica but is_______________________________________ Cosmopolitan in its distribution Prevalence in U.S. is estimated at _________ %; prevalence in tropics may be up to 100%

22. Entamoeba coli life cycle stages 1. TROPHOZOITE - 20 to 30  m in diameter - granular endoplasm is coarser than E. histolytica - structure of nucleus: ____________________________________________ ________________________________________________________________ - lives in large intestine and feeds on bacteria and any other cells available to it; does not invade tissue

23. Entamoeba coli life cycle stages 2. CYST - encystment is similar to that of E. histolytica - immature cysts are rare in fecal smears - mature cyst is large, 10 to 33  m, has _____ nuclei - chromatoidal bodies, if present, have splinter-like ends (disappear in most cysts) - cyst is released in the feces into the external environment - importance of human infection?

24. Entamoeba coli life cycle

25. Endolimax nana Non-pathogenic parasite in the _______________________________________________________________ Cosmopolitan - __________ prevalence in the world 2 stages in the life cycle: 1. TROPHOZOITE - small in size; 6 - 15 µm (usually under 10  m) - structure of nucleus: - moves slowly; feeds on bacteria and food debris

26. Endolimax nana 2. CYST - forms as feces dehydrates - small in size (5 - 14  m) - contains ____ nuclei with large endosomes - importance of human infection:

27. Endolimax nana life cycle

28. Iodamoeba b ü tschlii = I. buetschlii Parasite in the ___________________________________________________ Non-pathogenic Cosmopolitan in distribution Prevalence in world is ___________ (much less than E. coli & Endolimax)

29. Iodamoeba b ü tschlii = I. buetschlii 1. TROPHOZOITE - 9 to 20  m in diameter - structure of nucleus: - feed on bacteria and yeast; do not invade tissue

30. Iodamoeba b ü tschlii = I. buetschlii 2. CYST - 6 to 15  m in diameter - ________________ nucleus with large endosome and lightly-stained granules - large ___________________________ (appears clear) in cytoplasm - stains deeply with iodine; hence, the genus name Method of human transmission:

31. Iodamoeba b ü tschlii life cycle

32. 3 Other Non-Pathogenic Amebae (we will not examine these in lab) Entamoeba hartmanni Originally thought to be a "small race" of E. histolytica , it is now considered to be a separate species. The morphology of E. hartmanni is nearly identical to E. histolytica except it is SMALLER IN SIZE - trophozoites are typically 12 - 15  m in diameter - nuclear structure is similar (endosome in center) but peripheral chromatin is more irregular - cysts are 5 - 9  m in diameter and contain 4 nuclei Pathology: Importance:

34. Entamoeba gingivalis Habatit: Hosts: Prevalence is from 50 to 95%. Stage: Trophozoite lives on the surface of teeth and gums. Parasites feed on epithelial cells of the mouth, bacteria, food debris, and other cells available to them. Organisms are more common in persons with pyorrhea (gum disease) but they are not the cause of the condition. Transmission:

35. Facultative Amebae Facultative amebae are normal inhabitants of soil and water where they feed on bacteria. A few members have the ability to become parasitic when an opportunity to enter a vertebrate exists. Three are able to infect humans: Naegleria fowleri This ameba is responsible for over 200 cases of _____________________________________________________ During 1989-2000, CDC documented 24 fatal cases of PAM in the United States. Only 7 cases were successfully treated; all others were fatal!

36. Naegleria fowleri Trophozoites can occur as an ameboid form or a flagellated form in freshwater. Parasite can form a cyst in dry periods. Flagellated trophozoites enter the nasal passages when a victim swims or dives into freshwater. All victims have had a history of _______________________________________________________________________________________a few days before the onset of symptoms

37. Naegleria fowleri Once it enters a human, the parasites always revert to the ameboid form. - contains ____________________________________ - usually forms ____________________________________

38. Naegleria fowleri pathology After entering the nose and nasal cavities, the trophozoites migrate along the ___________________________ to the _________________________ Ameboid trophozoites multiply rapidly by binary fission in the brain and cause ___________________________________ Symptoms include a headache, fever, neck rigidity, and mental confusion followed by coma and death Death usually occurs in ___________________________

40. Naegleria fowleri TREATMENT – the drug __________________________ has been successful in the treatment of only 7 cases DISTRIBUTION - Most cases of this disease have been in the _____________________ U.S. (see case reports in lab). Cases have also been described in Europe, Africa, and Australia. I n Wisconsin?

43. Acanthamoeba spp. pathology (2) I ncriminated in a number of cases of __________________________ (inflammation and opacity of the cornea). Most of these ocular infections were in contact lens wearers who used home-made saline It appears that a ____________________ or swimming with contact lenses were necessary for invasion Diagnosis by identifying amebae in corneal scrapings Drug treatment has been successful in most cases Several cases have been reported in Wisconsin - see case reports in lab