1. The Protozoans
Mr. F. V. Po, RMT

2. Taxonomic Classification of Protozoans
Subphylum Class
Sarcodina Lobosea (Amebas)
Subphylum
Sarcomastigophora
Class
Subphylum Zoomastigophora
Mastigophora (Hemoflagellates/
flagellates
Subkingdom Phylum Class
Ciliophora Kinetofragminophorea
Protozoa (Ciliates)
Phlyum Class
Apicomplexa Sporozoa

3. The Intestinal Amebae

4. General Characteristics of Amebae
The most important feature that separates amebae from
other groups of Protozoans us the presence of
pseudopods in their trophozoite form.
Amebae have two morphologic forms: The cyst
and the trophozoite form.
Trophozoites are delicate, fragile and
motile.
The life cycles of all the intestinal amebae
are similar.
Replication is by binary
fission.

5. Entamoeba coli
Entamoeba coli
Common Name none
Infective Stage Mature cyst (Commensal; non-pathogenic)
Diagnostic Specimen Stool
Mode of Transmission Ingestion of cyst via contaminated food/ water
Disease Caused None (non-pathogenic)

6. Cysts of Entamoeba coli
Entamobea coli cysts

7. Entamoeba histolytica
Entamoeba histolytica
Common Name none
Infective Stage Mature Quadronucleated cyst
Diagnostic Specimen Stool
Mode of Transmission Ingestion of cyst via contaminated food/ water

8. Trophozoites of Entamoeba histolytica

11. Differentiation of E. coli and E. histolytica
Characteristics E. histolytica cyst E. coli cyst
Size range 8 to 22 um 8 to 35 um
Shape spherical to round Spherical to round
Number of nuclei one to four one to eight
large, irregular shape,
Karyosome small and central eccentric
Peripheral coarse and unevenly
Chromatin fine and evenly distributed distributed
Cytoplasm Finely granular coarse
Cytoplasmic chromatoid bars, rounded Thin, splintered chromatoid
inclusions ends bars
Diffuse glycogen mass Diffuse glycogen mass

12. Iodamoeba butschlii
Iodamoeba butschlii
Common Name none
Infective Stage Mature cyst
Diagnostic Specimen Stool
Mode of Transmission Ingestion of cyst via contaminated food/ water

13. Iodamoeba butschlii trophozoites, trichrome stained

14. Endolimax nana
Endolimax nana
Common Name none
Infective Stage Mature cyst
Diagnostic Specimen Stool
Mode of Transmission Ingestion of cyst via contaminated food/ water

15. Trophozoites of Endolimax nana

16. The Free Living Amebae

17. Acanthamoeba species
Acanthamoeba species
Common Name none
Infective Stage Mature cyst
Diagnostic Specimen CSF, brain tissue, and corneal scrapings
Mode of Transmission Inhalation of infective cyst or penetration through mucosa
Disease Caused Granulomatous Amebic Encephalitis (GAE)

18. Naegleria fowleri
Naegleria fowleri
Common Name none
Infective Stage Mature cyst
Diagnostic Specimen CSF
Penetration of ameboid trophozoite to nasal mucosa in
Mode of Transmission contaminated water or inhalation of cyst in dust particles
Disease Caused Primary Amebic Meningocencephalitis (PAM)

19. The Flagellates

20. Trichomonas vaginalis
Trichomonas vaginalis
Common Name none
Infective Stage Trophozoite (there is no known cyst stage)
Diagnostic Specimen Vaginal discharge, Urine sediments, prostatic secretion
Mode of Transmission Sexual intercourse
Disease Caused Vaginitis, urethritis (of amebic origin)

21. A Closer Look (Trichomonas vaginalis)

22. Chilomastix mesnili
Chilomastix mesnili
Common Name none
Infective Stage Cyst
Diagnostic Specimen Stool
Mode of Transmission Ingestion of cyst via contaminated food/ water
Disease Caused Not pathogenic

23. A Closer Look (Chilomastix mesnili)
C. mesnili cyst
C. mesnili
trophozoite

24. Giardia lamblia
Giardia lamblia
Common Name None
Infective Stage Mature cyst
Diagnostic Specimen Stool
Ingestion of mature infective cyst via contaminated food/
Mode of Transmission water
Disease Caused Traveler’s Diarrhea (Giardiasis)

25. A Closer Look (Giardia lamblia)
G. lamblia
Cyst

26. The Hemoflagellates

27. An Introduction to the Hemoflagellates

30. Leishmania species
Leishmania species
Common Name None
Infective Stage Promastigotes
Diagnostic Specimen Giemsa stained blood smear from infected area
Mode of Transmission Bite of infected sandfly

31. Leishmania species Differentiation
Leishmania species Vector Disease Caused Geographic location
Sandflies (Lutzomyia, Mucocutaneous South American
Leishmania braziliensis Psychodopygus) Leishmaniasis Countries
Sandflies (Lutzomyia, Visceral Leishmaniasis (Kala-
Leishmania donovani Complex Phlebotomus) azar)
Central and South
L. donovani chagasi America
Africa, India, Thailand,
L. donovani donovani Pakistan
Europe, Africa,
L. donovani infantum Northern China
Sandflies
Leishmania tropica Complex (Phlebotomus) Cutaneous Leishmaniasis/
Highlands of Ethiopia,
L. aethiopica Old World Leishmaniasis/ Kenya
USSR, Iran, Israel,
L. major Oriental Sore/ Jordan etc..
Afghanistan, India,
L. tropica Baghdad/ Deli Boil Kenya etc..

32. Trypanosoma cruzi
Trypanosoma cruzi
Common Name none
Infective Stage Trypomastigotes
Diagnostic Specimen Blood
Bite from defecating reduviid bug, blood transfusion, sexual
Mode of Transmission intercourse, transplacental transfer
Disease Caused Chagas’ Disease

33. Miscellaneous Protozoa

34. Balantidium coli
Balantidium coli
Common Name None
Infective Stage Cyst
Diagnostic Specimen Stool
Mode of Transmission Ingestion of cyst via contaminated food/ water
Disease Caused Balantidiasis

35. Toxoplasma gondii
Toxoplasma gondii
Common Name None
Infective Stage Oocyst
Diagnostic Specimen Serum (serologic tests)
Ingestion of oocyst, ingestion of undercooked contaminated
Mode of Transmission cattle/ pig/sheep, transplacental transfer, blood transfusion
Toxoplasmosis/ Cerebral Toxoplasmosis/ Congenital
Disease Caused Toxoplasmosis

36. Life Cycle of Toxoplasma gondii

37. Blastocystis hominis
Blastocystis hominis
Common Name None
Infective Stage Thick walled cyst
Diagnostic Specimen Stool
Mode of Transmission Ingestion of cyst
Treatment Abdominal cramping, diarrher, vomiting, nausea, fever

39. The Plasmodia

41. General Characteristics of Plasmodia
The typical life cycle of each of the Plasmodium organism involves over
two dozen morphologic forms. However, only 6 of the most commonly
encountered forms in human specimens will be discussed and are listed
chronologically:
Ring Forms (Early Trophozoites)
Developing Trophozoites
Immature Schizonts
Mature Schizonts
Microgametocytes
Macrogametocytes

42. Identification of Plasmodia

43. Identification of Plasmodia

44. Identification of Plasmodia

45. Identification of Plasmodia

46. Identification of Plasmodia

47. Plasmodium vivax

48. Plasmodium ovale

49. Plasmodium malariae

50. A Recaptiulation
Plasmodium vivax Typical Characteristics at a Glance
Relative age of infected
RBC Young and Immature RBC
Appearance of Infected
RBC Enlarged, distorted
Morphologic Form Typical characteristics (based on Giemsa Stain)
Ring Form Delicate cytoplasmic ring measuring 1/3 RBC diameter
single chromatin dot
ring surrounds a vacuole
Developing Trophozoite Irregular ameboid appearance
Ring remnants common
brown pigment
Immature Schizont Multiple chromatin bodies
brown pigment
Mature Schizont 12 to 24 merozoites occupying majority of the RBC's
merozoites surrounded by cytoplasmic material
brown pigment may be present
large pink to purple chromatin mass surrounded by colorless to
Microgametocytes pale halo
brown pigment common
Macrogametocytes round to oval cytoplasm
eccentric chromatin mass

51. A Recapitulation cont’d
Plasmodium ovale Typical Characteristics at a Glance
Relative age of Infected
RBC young and immature RBC's
Appearance of Infected
RBC oval and enlarged, distorted with ragged cell membranes
Morphologic Form Typical characteristics (based on Giemsa Stain)
Ring Form Resembles that of P. vivax
Ring larger in size than P. vivax
Ring often thick and somewhat ameboid in appearance
Ring appearance usually maintained until late in
Developing Trophozoite development
Ameboid tendencies not as evident as in P. vivax
Progressive dividing chromatin surrounded by cytoplasmic
Immature Schizont material,
often maintains circular shape early in development
Mature Schizont Parasites occupy three quarters of the RBC
Rosettes of an average of 8 merozoites
Micro/
Macrogametocytes Similar to P. vivax, only smaller in size

52. A Recapitulation cont’d
Plasmodium malariae Typical Characteristics at a Glance
Relative age of infected RBC's mature RBC's
Appearance of infected RBC's normal size; no distortion (mature cells are not pliable anymore)
Morphologic Form Typical Characteristics (based on Giemsa stain)
Ring Form smaller in size than P. vivax
occupies 1/6 of the RBC
heavy chromatin dot
vacuole may appear "filled in"
pigment forms early
Developing Trophozoite Non-ameboid soild cytoplasm that may assume a roundish, oval
band, or bar shape
Cytoplasm contains coarse dark brown pigment that may mask
chromatin material
vacuoles are absent in mature stages
Immature Schizont Similar to that of P. vivax, only smaller and may contain large and
dark peripheral or central granules
Mature Schizont 6-12 merozoites arranged in rosettes or irregular clusters
central arrangement of brown-green pigment may be visible
Macro/ Microgametocyte Similar to P. vivax, only smaller in size and pigment is usually
darker and more coarse
Older forms assume an oval shape

53. A Recapitulation cont’d
Plasmodium falciparum Typical Characteristics at a Glance
Relative age of Infected RBCs May infect cells of all ages
Appearance of infected RBCs Normal size; no distortion
Morphologic Form Typical characteristics (based on Giemsa stain)
Ring Form Circle configuration (one chromatin dot) or headphone
configuration (two chromatin dots)
Scanty cytoplasm and small vacuole
Multiple rings common
Accole forms common
Developing Trophozoite "heavy rings" common
Fine pigment granules
Mature forms only seen in severe infections
Immature Schizont Multiple chromatin bodies surrrounded by cytoplasm
Only detected in severe infections
Microgametocyte Sausage or crescent shaped
Dispersed central chromatin with nearby black pigment visible
Macrogametocyte Sausage or crescent shaped
Compact chromatin
Black pigment visible