Parasitic Protozoa, Fungi, and Helminths: Key Infections and Pathogens

Entamoeba histolytica (cysts & trophs)

Amebiasis (aka amoebic dysentery)

Protozoa - Amoebozoa

fecal-oral route - cysts in feces contaminate water

actin microfilaments, pseudopodia

Giardia lamblia (cysts & trophs) (also G. intestinalis or G. duodenalis)

Giardiasis

Protozoa - Excavata
fecal-oral route - cysts in feces contaminate water

have an excavate (depression on surface of cell)

Trichomonas vaginalis

Trichomoniasis

Protozoa - Excavata

sexually transmitted disease (STD)

flagellae, mononucleate, granular

Trypanosoma brucei gambiense

African Trypanosomiasis (aka African Sleeping Sickness)​

Protozoa - Excavata

diagnosed from blood smear, parasitic

undulating, squiggly membrane

Balantidium coli (cysts & trophs)

Balantidiasis

Protozoa - Chromalveolata

fecal-oral, parasitic intestinal illness, rarely serious unless immunocompromised

ciliated, apical complex

Plasmodium falciparum

Malaria (anopheles sp. mosquito)

Protozoa - Chromalveolata

diagnosed via blood smear

“diamond ring” shape in RBC

Cryptosporidium parvum

Cryptosporidiosis

Protozoa

fecal-oral route - cysts in water; intestinal symptoms + diarrhea

diagnosed via fecal smear

Amoeba proteus

Pseudopodia, amorphous

Protozoa - Amoebozoa

Paramecium caudatum

Ciliated

Protozoa

Candida albicans

Candidiasis (skin and nails, vaginal yeast infection, oral thrush)

Fungi - ascomycota, pseudohyphae + daughter buds

fungal yeast infection, lives on skin normally

diagnosed via evaluation of secretions

Aspergillus sp.

Aspergillosis (cutaneous & respiratory)

Fungi - ascomycota (septate hyphae), both ascospores (sexual) and conidia (asexual)

bread mold, respiratory transmission, diagnosed via patient history/culturing

Rhizopus sp.

Mucormycosis

Fungi - zygomycete (nonseptate hyphae), saphrophytic, asexual sporangiospores (zygospores), haploid nuclei

sporangium, “puffy ball”

Penicillium notatum

Source of penicillin, “spirit fingers”

Fungi - ascomycota (septate hyphae), conidia (asexual)

Trichinella spiralis

Trichinosis (aka trichenellosis)

Helminth (nematoda, roundworm)

diagnosed via biopsy/serological testing

Schistosoma mansoni

Schistosomiasis

Helminth (platyhelminth, flatworm) - fluke (trematode)

fecal-oral (and urinal/gastrointestinal) route

freshwater snails

Fasciola hepatica

Fascioliasis

Helminth (platyhelminth, flatworm) - fluke (trematode)

Taenia sp.

Taeniasis

Helminth (platyhelminth, flatworm) - cestode (segmented)

pork/beef consumption

diagnosed via fecal smear

Clonorchis sinensis

Clonorchiasis

Helminth (platyhelminth, flatworm) - fluke (trematode)

fish consumption

Enterobius vermicularis

Enterobiasis

Helminth (nematoda, roundworm)

aka Pinworm, most common nematode infection in U.S.

fecal-oral route - eggs laid in anal area at night

Ascaris lumbricoides

Ascariasis

Helminth (nematoda, roundworm)

fecal-oral route

fecal smear

Necator americanus

Hookworm

Helminth (nematoda, roundworms)

fecal-oral route

fecal smear

Trichuris trichiura

Trichuriasis

Helminth (nematoda, roundworm)

aka whipworm

fecal-oral route

fecal smear