Protozoan Parasites Review: Amoebae, Flagellates, and Ciliates

A set of vocabulary-style flashcards covering key parasites from the lecture notes, including free-living amoebae, atrial flagellates, and hemoflagellates (Giardia, Trichomonas, Balantidium, Dientamoeba, Chilomastix, Leishmania, Trypanosoma).

Acanthamoeba

Genus of free-living amoebae that can cause granulomatous amoebic encephalitis (GAE); several species include culbertsoni, polyphaga, castellani, and astronyxis.

Naegleria fowleri

Free-living amoeba that causes Primary Amoebic Meningoencephalitis (PAM); infective form is the trophozoite (with flagellate forms possible); acquired by inhalation of contaminated water or soil.

Primary Amoebic Meningoencephalitis (PAM)

Acute, often fatal CNS infection caused by Naegleria fowleri.

Granulomatous Amoebic Meningoencephalitis (GAE)

Chronic CNS infection caused by Acanthamoeba species.

Cyst (amoebae life stage)

Double-walled dormant form with endocyst and ectocyst; walls may be polyhedral or stellate and vary between species.

Trophozoite

Motile feeding stage; can be amoeboid or flagellate; may have a uroid and food vacuoles.

Acanthamoeba culbertsoni

One of the Acanthamoeba species associated with granulomatous amoebic encephalitis.

Acanthamoeba polyphaga

Acanthamoeba species linked to granulomatous amoebic encephalitis.

Acanthamoeba castellani

Acanthamoeba species linked to granulomatous amoebic encephalitis.

Acanthamoeba astronyxis

Acanthamoeba species associated with GAE.

Source of infection (Naegleria fowleri)

Soil and fresh water; inhalation of contaminated water or dust as portal of entry.

Site of infection (Naegleria fowleri)

Meningitis and brain involvement following nasal exposure.

Acanthamoeba keratitis

Eye infection caused by Acanthamoeba, commonly associated with contact lens use.

Trichomonas vaginalis

Flagellate parasite causing trichomoniasis (vaginitis); infective stage is the trophozoite; transmitted via sexual contact.

Giardia duodenalis

Flagellate parasite that causes giardiasis; infective cysts are ingested in contaminated water/food; diagnosis via direct fecal smears.

Chilomastix mesnili

Non-pathogenic intestinal flagellate; cysts are lemon-shaped with nipple-like projection; trophozoite described as ’old man with eyeglasses’.

Trichomonas hominis

Non-pathogenic intestinal flagellate.

Trichomonas tenax

Non-pathogenic flagellate found in the oral cavity.

Balantidium coli

Ciliate agent of balantidiasis; cyst and trophozoite stages; large macronucleus; transmitted via contaminated water/food.

Dientamoeba fragilis

Intestinal parasite causing gastrointestinal symptoms; transmission via cysts; pathogenesis debated.

Leishmania donovani

Causes visceral leishmaniasis (kala-azar); vector is the sandfly; infective stage is promastigote; pathogenic stage in humans is amastigote.

Promastigote

Flagellated stage of Leishmania in the sandfly vector; infective form transmitted to humans.

Amastigote

Intracellular stage of Leishmania within macrophages in humans.

Trypomastigote

Bloodstream stage of Trypanosoma spp.; infective form in many human infections (e.g., T. brucei, T. cruzi).

Trypanosoma gambiense

Cause of chronic African sleeping sickness; vector is the tsetse fly (Glossina); infective stage the trypomastigote; definitive host is human.

Trypanosoma rhodesiense

Cause of acute African sleeping sickness; vector is the tsetse fly; infective stage the trypomastigote.

Trypanosoma cruzi

Cause of Chagas disease; transmitted by kissing bugs (Triatomine); infective stage is trypomastigote; post-bite transmission via feces.

Leishmaniasis vectors

Sandflies (Phlebotomus spp.) transmit Leishmania parasites to humans.

Tsetse fly

Vector for Trypanosoma brucei species causing African sleeping sickness.

Kissing bug (Triatomine)

Vector for Trypanosoma cruzi; transmits via feces when biting.

Anterior transmission

Transmission via vector’s mouthparts during the bite, delivering pathogens into the host.

Posterior transmission

Transmission via vector’s feces after biting (e.g., T. cruzi).

Winterbottom sign

Posterior cervical lymphadenopathy associated with visceral leishmaniasis.