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active feeding stage of protozoa


survival stage of protozoa, organelles double

Trichrome Stain

always use for ID confirmation

Giardia lamblia

Pathogenic flagellate protozoa, known as "Beaver Fever" found worldwide
-Ingest infective cyst form contaminated food, drink, breakdown in sanitation
-Excyst in duodenum
-Trophs attach to large intestine
-Encystment in large intestine
-Diagnosed using Trichrome stains, O&Px3, up to 3 stools may be required, looking for cysts!

Giardia lamblia (Trophozoite Diagram)

Giardia lamblia Trophozoite

Giardia lamblia (Cyst Diagram)

Giardia lamblia Cyst

Trichomonas vaginalis

Pathogenic Flagellate Protozoa
-No Cyst stage
-Diagnosed by "Twitchy motility" if kept warm
-Difficult to recognize on a permanent stain
-Troph in tissue and secretions
-Males asymptomatic

Trichomonas vaginalis (Trophozoite Diagram)

Trichomonas vaginalis Trophozoite

Trichomonas hominis

Non-pathogenic Flagellate Protozoan, found worldwide
-No Cyst stage
-Motile is fresh stools
-Difficult to stain
-Oral-fecal transmission, treatment not recommended

Trichomonas hominis (Trophozoite Diagram)

Trichomonas hominis Trophozoite

Chilomastix mesnili

Non-pathogenic Flagellate Protozoa
-lives in cecal region of large intestine
-fecal-oral transmission
-looks like yeast
-"Pear Shaped"

Chilomastix mesnili (Trophozoite Diagram)

Chilomastix mesnili Trophozoite

Chilomastix mesnili (Cyst Diagram)

Chilomastix mesnili Cyst

Balantidium coli

Pathogenic Ciliate Protozoa
-Causes Dysentary with persistent diarrhea beforehand
-Can't function w/o macronucleus, "kidney bean-shaped"
-Wet preps are best for viewing, can be confused with helmenth egg
-Domestic hogs are reservoir in Subtropics/Tropics
-Ingestion of infective cysts in food, water

Balantidium coli (Trophozoite Diagram)

Balantidium coli Trophozoite

Balantidium coli (Cyst Diagram)

Balantidium coli Cyst

Intestinal Amebae

-Motile by pseudopodia
-Have Trophozoites & Cysts


-The combination of DNA and proteins that make up the contents of the nucleus of a cell.
-Stains red/Purple

Peripheral Chromatin

Wavy outerlayer


Chromatin material inside cell nucleus (separate piece in center)

Entamoeba histolytica & E. dyspar

Worldwide Pathogenic Amoeba
Amoebic Lifecycle:
-Asymptomatic=Passing cysts, Negative for Occult Blood, cysts survive in cold
-Morphologically identical to E. hartman (which is smaller)
-Oral-Fecal Transmission

-Ingested RBCs give away diagnosis
-Max 4 nuclei
-Mucosal penetration, ulcers in cecum, appendix, spread to brain, lung, liver, much Dysentary
-MUST use permanent stain to confirm ID, negative on Occult Blood
-Cysts survive longer in Cold=28-34C
-Have peripheral chromatin and karyosome

Entamoeba histolytica

Nuclear Morphology of:

Entamoeba histolytica & E. dyspar (Trophozoite Diagram)

Entamoeba histolytica & E. dyspar Trophozoite

Entamoeba histolytica & E. dyspar Trophozoite with WBCs

Entamoeba histolytica & E. dyspar (Cyst Diagram)

Entamoeba histolytica & E. dyspar Cyst

Entamoeba histolytica & E. dyspar Cyst with Glycogen vacule (Unmatured)

Entamoeba hartmanni

NonPathogenic Amoeba
-Oral-Fecal transmission
-No treatment recommended
-SAmoebic Lifecycle, E. histolytica=larger
-Diagnoses on Permanent stain with NO ingested RBCs

Entamoeba hartmanni

Nuclear Morphology of:

Entamoeba hartmanni (Trophozoite Diagram)

Entamoeba hartmanni Trohpozoite

Entamoeba hartmanni (Cyst Diagram)

Entamoeba hartmanni Cyst

L=Entamoeba histolytica
R=Entamoeba hartmanni

Notice Size Difference in Trophozoites, Which is which?

Entamoeba coli

Worldwide NonPathogenic Amoeba
-Amoebic Lifecycle
-Mature cysts most diagnostic on permanent stains, NO ingestion of RBCs
-Oral-Fecal transmission
-Off center karyosome, random peripheral chromatin, >4 nuclei

Entamoeba coli

Nuclear Morphology of:

Entamoeba coli (Trophozoite Diagram)

Entamoeba coli Trophozoite

Entamoeba coli (Cyst Diagram)

Entamoeba coli Cyst

Endolomax nana

Worldwide NonPathogenic Amoeba
-Like warm, moist regions
-Amoebic Lifecycle
-If using iodine wet prep instead of trichrome stain, you won't be able to see nucleus
-Have 4 nuclei with blot-like karyosome

Endolomax nana

Nuclear morphology of:

Endolomax nana (Trophozoite Diagram)

Endolomax nana Trophozoite

Endolomax nana (Cyst Diagram)

Endolomax nana Cyst

Iodamoeba butschii

Worldwide NonPathogenic Amoeba
-Likes tropics

Iodamoeba butschii

Nuclear Morphology of:

Iodamoeba butschii (Trophozoite Diagram)

Iodamoeba butschii Trophozoite

Iodamoeba butschii (Cyst Diagram)

Iodamoeba butschii Cyst

Notice the Glycogen Vacule!

Blastocystis hominis

Amoeba, Sometimes Pathogenic, when numerous
-Usually commensile
-Oral-Fecal Transmission
-Symptoms: diarrhea, cramps, nausea, fever, vomiting, abdominal pain
-Seen in Vacoulated Form, but also exists as granulated form, amoebic form, and cyst form.

Blastocystis hominis (Vacoulated Form Diagram)

Blastocystis hominis Vacuolated Form

Blastocystis hominis ("Dividing")

Dientamoeba fragilis

Worldwide Pathogenic Flagellate
-No cyst stage!!
-Asymptomatic carrier state, then diarrhea, abdominal pain, blood/mucus in stool, gas nausea, vomiting, weight loss, fatigue
-Diagnosis made on Permanent Stains with multiple specimens
Possible association with helminth infections, transmitted via ova?
-Troph looks like "oval with eyes"

Dientamoeba fragilis

Nuclear Morphology of:

Dientamoeba fragilis (Trophozoite Diagram)

Dientamoeba fragilis Trophozoite


-Infect intestinal mucosa
-Cause diarrheal illness in humans
-Oocysts are diagnostic stage and are spore-like in the fact that they are resistant
-Sporozoites start inside Oocyst

Cryptosporidium parvum

Pathogenic Sporozoa
-From "Baby Cows"
-Causes Cryptosporidiosis
-Systemic spread with immunocompromised, life threatening with HIV+
-Significant morbidity and mortality
-Look like yeasts, Use modified ACID FAST STAINS->AF=pink
-Fecal-Oral water/food Transmission
-Biggest outbreak in US, in Milwaukee in '92, water treatment plant from river
Schizonts, Merozoites, Gametocytes, Oocysts, Sporozoites

Cryptosporidium parvum (Diagram)

Cryptosporidium parvum

Cryptosporidium parvum

Cyclospora cayetanensis

-Larger than parvum, longer duration, and more sever effects
-Diagnosed on wet preps, modified ACID FAST STAIN
-Looks like "Perfectly Round," "Cut Glass"/"Nut Bowl" using trichrome stain, doesn't stain Oocyst

Cyclospora cayetanensis

Cyclospora cayetanensis

Cyclospora cayetanensis

Isospora belli

-No intermediate hosts, Humans are DEFINITIVE host!
-Use modified ACID FAST STAIN
-Transmission from contaminated food/water, Sexual transmission!!
Oocysts, Sporoblasts, Sporocysts, Sporoxoites

Isospora belli (Diagram)

Isospora belli

Isospora belli

Toxoplasma gondii

-Causes Toxoplasmosis, AKA: Cat Scratch Disease
-MOST SUCCESSFUL Human parasite
-Serologic testing, during preganancy, can cross placenta, part of TORCH titer
-Transmission=ingest oocysts
-Many intermediate hosts
-Cats are definitive hosts
-Mimics Mono
Tachyzoites, Bradyzoites, Oocysts

Toxoplasma gondii (Diagram)


-Metabolically reduced specialized fungi, mostly in insects
-Obligate, intracellular, spore-forming protists
-7 genera infect humans, Enterocytozoon bienuesi
-Mainly in immunocompromised
-Trichrome, Giemsa stains



-Worldwide cause of mosquito-acquired malaria if traveled recently
-Complex lifecycles- Stages: Ring forms (early torphozoites), Developing trophozoites, Immature schizonts, Mature schizonts (with merozoites), Microgametocytes, Macrogametocytes
-First week=asymptomatic, asynchronous division, Rupturing RBC's at different times. Symptoms most prominent when they are synchronized.
-Used to control Syphilis with plasmodium
-Fever spikes in cycles

Plasmodium vivax

Fever spikes at 48 hrs

Plasmodium vivax

Plasmodium ovale

Fever spikes at 48 hrs

Plasmodium ovale

Plasmodium malariae

Fever spikes at 72 hrs

Plasmodium malariae

Plasmodium falciparum

Fever spikes at 36-48 hrs
-Affects the brain
-Only parasite that can be potentially immediately fatal

Plasmodium falciparum

Plasmodium knowlasi

-Newest, only in a small area

"Signet Ring"

Appears on Early Trophozoite. Forms before Hepatic stage- when plasmodium enters liver and sets up camp. Reproduces and breaks out of liver, into RBC's, this is where its diagnosed. Busts out of cell and starts over. Classic signs start when it keeps reproducing/cycling.


Erythrocytic cycle not eliminated, Symptoms return quickly


Erythrocytic cycle eliminated, Reinfection of RBC's from liver, Return of symptoms much delayed >20 yrs.


Worldwide Protozoa
-Rodent is intermediate host
-TX by ticks
-General malaise, fever, chills
-Self-limiting infection
-Mimics P. falciparum ring forms with "Maltese cross" instead of signet ring


-Stages: Amasitgote, Promastigote, Epimastigote, Trypomastigote
-Amastigote is non flagellated stage where it grows and eventually kills macrophage that ate it

Hemoflagellate Stages

"Looks like Platelets"
Mostly will see with flagella in mature stage

Hemoflagellate with Epimastigotes

Burst Macrophage

Trypomastigote Stage

Trypanosoma brucei gambesiense

West African Sleeping Sickness
-West/Central Africa
-Tsetse fly is insect host/vector
-Chancer at bite site, swollen lymph nodes, apathy, fatigue, death
-Diagnosis from blood smears, pt history, both amastigotes and trypomastigotes present

Trypanosoma brucei rhodesiense

East African Sleeping Sickness
-East/Central Africa
-Tsetse fly is insect host/vector
-Early CNS involvement, more aggressive
-Diagnosis from blood smears, pt history, both amastigotes and trypomastigotes present, highly infectious- can go through skin if not covered!
-Many ANIMAL reservoirs

Trypanosoma cruzi

Chaga's Disease
-South/Central America
-Reduvid bugs are insect host/vector
-Invades many organs, especially heart
-Painful nodule on face, rash around eyes
-Death as early as several weeks after attack
Diagnosis from blood smears, pt history, both amastigotes and trypomastigotes present


-Sandfly is insect host/vector
-Obligate intracellular (macrophage) parasites
-Painless papule at bite site, secondary bacterial/fungal infections, Eats away at tissue like cancer and spread throughout body with macrophages- DEADLY
-No flagellated forms in humans, only amastigotes (in macrophages)

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