Parasitic Amoeba and Atrial Flagellates

This set of vocabulary flashcards covers key parasitic amoebas and atrial flagellates, including their morphology, pathogenesis, and diagnostic features as described in the lecture notes.

Rhizopodea

The class under which most amoeba parasites that can infect humans are classified.

Pseudopodia

The locomotion organelle present in the trophozoite form of amoebas.

Entamoeba gingivalis

An amoeba species that inhabits the oral cavity and exists in the trophozoite form only.

Entamoeba histolytica

The only species of Entamoeba that is pathogenic to man and is the causative parasite of amoebiasis.

Excystation

The process occurring in the neutral or alkaline later part of the small intestine where the parasite breaks out of the cyst.

Metacystic trophozoites

The four daughter organisms produced by each mature $E. histolytica$ cyst.

Chromatoidal bodies

Structures containing proteins stored in the cytoplasm during encystation; in $E. histolytica$, they are cigar-shaped or have rounded ends.

Cyst passers

Infected individuals, often asymptomatic carriers, whose stool contains infective cysts.

Flask-shaped ulcer

The typical lesion of an amoebic ulcer produced when trophozoites extend intestinal ulcers sideward into the muscular layer.

Amoeboma

A granuloma formed by the stimulation of fibrous tissue in the intestinal tract that may be mistaken for a tumor.

Anchovy-sauce-like appearance

The characteristic appearance of a liver abscess caused by the lysis of liver cells by $E. histolytica$ trophozoites.

Amoeba cutis

A skin lesion characterized by edema and skin necrosis resulting from a sinus tract from a liver abscess or recto-sigmoid colon.

Polyvinyl alcohol (PVA)

A preservative used for fecal samples that can preserve both cyst and trophozoite forms, though motility is lost.

Entamoeba dispar

A non-invasive, non-pathogenic amoeba morphologically identical to $E. histolytica$ but distinguished by PCR test.

Bullseye karyosome

A diagnostic feature of the single, spherical, vesicular nucleus in $E. histolytica$ trophozoites and cysts.

Metronidazole

The treatment of choice for extraluminal amoebiasis and invasive infections like liver abscesses.

Entamoeba coli

A commensal parasite with a "dirty looking" cytoplasm containing vacuoles and bacteria, often having up to 8 nuclei in its mature cyst form.

Entamoeba hartmanni

Formerly known as "small race" $E. histolytica$, a commensal whose cysts measure less than 10̂m.

Endolimax nana

A harmless commensal characterized by "slug-like" motility in trophozoites and a "cross-eyed" appearance in stained cysts.

Iodamoeba butschlii

A commensal amoeba known for a large glycogen mass that stains mahogany-brown with Lugol's iodine, also called the "Iodine cyst of Wenyoun."

Naegleria fowleri

Known as the "brain-eating amoeba," it is the causative parasite of Primary Amoebic Meningoencephalitis (PAM).

Ameboflagellate

A classification of Naegleria species because their developmental stages include both flagellate and amoeboid forms.

Uroid process

A knob-like structure at the posterior end of the $Naegleria fowleri$ amoeboid trophozoite.

Granulomatous Amoebic Meningoencephalitis (GAE)

A serious brain infection produced by species of Acanthamoeba, often secondary to infections in the skin or eyes.

Acanthopodia

Spine-like pseudopodia characteristic of the Acanthamoeba trophozoite stage.

Mastigophora

The subphylum to which atrial or luminal flagellates belong.

Giardia duodenalis

The etiologic parasite of giardiasis, also known as "traveler's diarrhea," characterized by falling-leaf motility.

Sucking disc

A ventral shallow concavity used by $Giardia duodenalis$ trophozoites for attachment to the intestinal wall.

Steatorrhea

Gruelly or fatty stools resulting from excessive mucus secretion and deranged fat absorption in giardiasis.

Chilomastix mesnili

A commensal flagellate with a lemon-shaped cyst and a trophozoite featuring an hourglass-shaped cytostome.

Undulating membrane

A membrane lining the body of trichomonads, used for locomotion along with flagella.

Trichomonas vaginalis

The only pathogenic species of trichomonads, inhabiting the genitourinary tract and causing "ping-pong infection."

Siderophile granules

Diagnostic granules filling the cytoplasm of $Trichomonas vaginalis$ trophozoites.

Dientamoeba fragilis

A flagellate-related amoeba that exists primarily as a binucleated trophozoite with a fragmented "tetracocci" karyosome.

Axostyle

A conspicuous, semi-rigid axial rod near the midline of trichomonads that often protrudes at the posterior end.