Week 9 ,, Protozoan Part 1

Trophozoite

The motile feeding stage that is able to undergo cell division

Cyst

The dormant infective stage that is released to the environment

Acanthamoeba spp. Infective Stage

Ingestion of trophozoite

Acanthamoeba spp. Diagnostic Stage

Cysts and trophozoites in the tissues

Acanthamoeba spp. Clinical Features

Acanthamoeba spp. Laboratory Diagnosis

Keratitis of the eye ,, Granulomatous amebic encephalitis (GAE), and/or disseminated disease ,, Skin lesions

Naegleria fowleri is also known as what?

The brain-eating amoeba

Naegleria fowleri Diagnostic Stage

Trophozoites in CSF and brain tissue (flagellated forms occasionally in CSF)

Naegleria fowleri Infective Stage

Trophozoites enters the body through the nasal mucosa

Naegleria fowleri Clinical Features

Severe headaches, fever, vomiting, neurologic deficits that progresses rapidly and frequently to coma/death

Naegleria fowleri Laboratory Diagnosis

Microscopic examination of CSF ,, Immunofluorescence ,, PCR

Excystation

The process where a parasitic organism escapes from its protective cyst wall or envelope after being ingested by a host

Entamoeba histolytica Infective Stage

Ingestion of mature cysts and cysts/trophozoites passed in feces

Entamoeba histolytica Diagnostic Stage

Presence of mature cysts and cysts/trophozoites in feces

Entamoeba dispar

Trophozoites and cysts are indistinguishable from E. histolytica

Entamoeba histolytica/dispar Mature Cyst Features

1, 2, or 4 nuceli ,, Centrally located karyosomes ,, Fine, uniformly distributed peripheral chromatin ,, 1-2 chromatoid bodies with blunted ends

Entamoeba histolytica/dispar Trophozoite Features

Single nucelus ,, Centrally placed karysome ,, Uniformly distributed peripheral chromatin ,, “Ground-glass” cytoplasm appearance

What is indicative of Entamoeba histolytica?

Erythrophagocytosis

Commensal Protozoa

Nonpathogenic ,, Presence of parasite increases the likelihood of pathogens being present ,, Misidentification leads to unnecessary treatment

Entamoeba dispar

Trophozoite and cyst are indistinguishable from Entamoeba histolytica

Entamoeba hartmanni

Morphologically identical to E. hisolytica/dispar ,, Trophozoites and cysts are smaller in size

Entamoeba coli

Trophozoites : Coarse, unevenly distributed peripheral chromatin ,, Large, irregular eccentric karysomes ,, Coarse, granular cytoplasm with numerous vacuoles and inclusions // Cysts : 1-8 nuclei ,, Inclusions such as chromatoidal bars with splintered ends and glycogen vacuoles

Endolimax nana

Trophozoite : Single nucleus with no peripheral chromatin ,, Large, blot-like karyosome can be pushed to one side , Numerous vacuoles with bacteria, yeast, and organic debris // Cysts : Spherical or ovid ,, 1-4 nuclei ,, No peripheral chromatin and large blot-like karyosome

Iodamoeba bütschlii

Trophozoites : 1 nucleus with no peripheral chromatin ,, Large blot-like karyosome that may be surrounded by small granules ,, Vacuoles and debris in cytoplasm // Cysts : Single nucleus with the same appearance as the trophozoite ,, Oval or spherical ,, Characteristic large glycogen vacuole (brown on iodine stained wet prep)

Dientamoeba fragilis

Prodcues trophozoites only ,, 1 or 2 nuceli ,, Delicate nuclear membrane and no peripheral chromatin ,, Symmetrically arranged chromatin granule in the center of the nucleus

Blastocystis hominis

Blastocystis

Blastocystis hominis Infective Stage

Ingestion of thick-walled cysts

Blastocystis hominis Diagnostic Stage

Presence of thick-walled cysts

Blastocystis hominis Clinical Features

May be associated with watery diarrhea, abdominal pain, perianal pruritus, and excessive flatulence

Blastocystis hominis Laboratory Diagnosis

Microscopic examination of cyst-like stage in feces ,, Permanently stained smears are preferred over wet mount preparations because fecal debris may be mistaken for organisms in the latter ,, Do NOT wash the specimens in water because it will lyse the organism, resulting in false negatives

Balantidium coli

Balantidiasis

Balantidium coli Diagnostic Stage

Trophozoites and cysts

Balantidium coli Infective Stage

Trophozoites and cysts

Balantidium coli Geographical Distribution

Worldwide but more frequent in areas where pigs (main reservior) are raised

Balantidium coli Clinical Features

Most cases are asymptomatic ,, May cause persistent diarrhea, occasionally dysentery (blood and mucus), abdominal pain, and weight loss

Balantidium coli Microscopic Examination

Tropozoites in stool specimens or tissue collected during endoscopy ,, Cysts are less frequently encountered ,, Stool speicmens should be collected repeatedly

Balantidium coli Trophozoite Features

Bean shaped macronucleus

Cryptosporidium ssp

Cryptoporidiosis

Cryptosporidium ssp Diagnostic Stage

Thich-walled oocyst (sporulated) exits the host

Cryptosporidium ssp Infective Stage

Ingestion of thick-walled oocyst ingested by host

Cryptosporidium ssp Clinical Features

From asymptomatic to severe, life-threatening illness ,, Watery diarrhea, dehydration, weight-loss, abdominal pain, fever, nausea, and vomiting ,, Symptoms can be chronic and more severe in immunocompromised patients ,, Can also be found extraintestinally in the lungs, and possibly conjunctiva

Cryptosporidium ssp Microscopic Examination

Modified Acid Fast Staining will stain the oocysts bright red against a background of blue-green fecal debris and yeast

Cyclospora cayetanensis

Cyclosporiasis

Cyclospora cayetanensis Infective Stage

Ingestion of sporulated oocysts in contaminated food/water

Cyclospora cayetanensis Diagnostic Stage

Excretion of unsporulated oocysts in the stool

Cyclospora cayetanensis Clinical Features

Watery diarrhea can be severe ,, Anorexia, weight loss, abdominal pain, nausea, vomiting, myalgias, low-grade fever, and fatigue

Cyclospora cayetanensis Microscopic Examination

Similar in appearance to Cryptosporidium oocysts but is twice the size and has a much thicker wall

Cystoisospora belli

Least common intestinal coccidia that infect humans ,, Ellipsoidal large oocysts

Giardia intestinalis

Common intestinal infection

Giardia intestinalis Clinical Features

Varies from asymptomatic to severe diarrhea and malabsorption ,, Greasy stool that tends to float (steatorrhea) ,, Abdominal pain, bloating, nausea, and vomiting

Giardia intestinalis Infective Stage

Ingestion of cysts in contaminated food or water

Giardia intestinalis Diagnostic Stage

Cysts and trophozoites passed in the stool (trophozoites do not survive in the environment)

Giardia intestinalis Laboratory Diagnosis

Direct mounts and concentration procedures for identification of cysts or trophozoites in the feces ,, Excreted intermittently, so repeated sampling may be necessary ,, Samples of duodenal fluid or duodenal biopsy may demonstrate trophozoites

Chilomastix mesneli

Nonpathogenic flagellate ,, Generally considered a commensal residing in the cecum and/or colon

Chilomastix mesneli Trophozoite Features

Lemon-shaped trophozoite with anterior hyaline knob ,, One nucleus with a well developed membrane and karyosome (only seen in stained preparations)

Trichomonas vaginalis

GU tract infection

Trichomonas vaginalis Infective Stage

Trophozoite in the vagina or orifice of the urethra ,, Can spread through sexual intercourse

Trichomonas vaginalis Diagnostic Stage

Trophozoite in vaginal and prostatic secretions and urine

Trichomonas vaginalis Clinical Features in Women

Vaginitis with a purulent discharge ,, Vulvar and cervical lesions, abdominal pain, dysuria and dyspareunia

Trichomonas vaginalis Clinical Features in Men

Frequently asymptomatic ,, Urethritis, epididymitis, and prostatitis

Trichomonas vaginalis Laboratory Diagnosis

Wet mounts to detect actively motile organisms (rapid but insensitive) ,, DFA (more sensitive but complex) ,, Culture of parasite (more sensitive but takes 3-7 days) ,, Samples

Identify the Protozoa

Entamoeba histolytica/dispar cyst

Identify the Protozoa

Entamoeba hystolytica/dispar trophozoites

Identify the Protozoa

Entamoeba hystolytica/dispar trophozoites

Identify the Protozoa

Entamoeba hartmanni cyst

Identify the Protozoa

Entamoeba hartmanni trophozoite

Identify the Protozoa

Entamoeba coli trophozoite

Identify the Protozoa

Entamoeba coli cyst

Identify the Protozoa

Endolimax nana trophozoite

Identify the Protozoa

Endolimax nana cyst

Identify the Protozoa

Iodamoeba bütschlii trophozoite

Identify the Protozoa

Iodamoeba bütschlii cyst

Identify the Protozoa

Dieniamoeba fragilis trophozoite

Identify the Protozoa

Blastocystic hominis

Identify the Protozoa

Balantidium coli

Identify the Protozoa

Balantidium coli

Identify the Protozoa

Cystoisospora belli

Identify the Protozoa

Cystoisospora belli

Identify the Protozoa

Giardia intestinalis

Identify the Protozoa

Giardia intestinalis trophozoite

Identify the Protozoa

Giardia intestinalis cysts

Identify the Protozoa

Chilomastix mesneli trophozoite

Identify the Protozoa

Giardia intestinalis tropozoite

Identify the Protozoa

Trichomonas vaginalis trophozoite