Parasitology – Intestinal & Tissue Parasites Vocabulary

Twenty-five vocabulary flashcards covering key helminths and protozoa, their associated diseases, diagnostic features, and notable clinical clues.

Enterobius vermicularis (Pinworm)

• Feature: Causes enterobiasis; classic symptom is perianal itching, especially in children.
• Keywords: Oval eggs with a flattened side; detected by cellulose tape test.

Trichuris trichiura (Whipworm)

• Feature: Responsible for trichuriasis; may produce bloody diarrhea and rectal prolapse in heavy infections.
• Keywords: Barrel-shaped eggs with bipolar plugs.

Ascaris lumbricoides (Giant intestinal roundworm)

• Feature: Causes ascariasis; heavy burdens can obstruct intestines or bile ducts.
• Keywords: Large cream-colored adults; thick mammillated eggs.

Hookworms (Necator americanus & Ancylostoma duodenale)

• Feature: Blood-feeding nematodes acquired by skin penetration; major cause of iron-deficiency anemia in people who walk barefoot.
• Keywords: Cutting plates/teeth in the buccal capsule.

Strongyloides stercoralis (Threadworm)

• Feature: Causes strongyloidiasis; risk of life-threatening hyperinfection in immunosuppressed patients.
• Keywords: Short buccal cavity larvae; capable of autoinfection.

Capillaria philippinensis

• Feature: Causes protein-losing enteropathy and chronic diarrhea; typically after eating raw or undercooked fish.
• Keywords: Slender intestinal nematode; small barrel eggs.

Anisakis spp.

• Feature: Marine nematodes whose coiled larvae embed in the gastric wall; ingestion of raw fish (sushi, sashimi) leads to acute gastric pain.
• Keywords: Often diagnosed by endoscopy.

Trichinella spiralis

• Feature: Larvae encyst within striated muscle causing trichinosis; manifests with myalgia, fever, and periorbital edema.
• Keywords: Acquired from undercooked pork or wild game.

Angiostrongylus cantonensis (Rat lungworm)

• Feature: Produces eosinophilic meningitis in humans.
• Keywords: Thin larvae with knobbed tail; acquired from raw snails or contaminated vegetables; eosinophils in CSF are characteristic.

Taenia saginata (Beef tapeworm)

• Feature: Causes taeniasis; motile proglottids may be seen in stool after eating undercooked beef.
• Keywords: Scolex has four suckers but no hooks.

Taenia solium (Pork tapeworm)

• Feature: Causes taeniasis and cysticercosis; ingestion of eggs (not cysticerci) can lead to cysts in brain, muscle, and eyes.
• Keywords: Scolex bears hooks.

Diphyllobothrium latum (Fish or broad tapeworm)

• Feature: Infection from raw freshwater fish; can cause vitamin B12 deficiency; is the longest human tapeworm.
• Keywords: Bothria (grooves) on scolex.

Hymenolepis nana (Dwarf tapeworm)

• Feature: Smallest cestode infecting humans; allows direct (autoinfective) life cycle without an intermediate host.
• Keywords: Eggs possess polar filaments.

Echinococcus granulosus (Dog tapeworm)

• Feature: Forms hydatid cysts with daughter cysts in human liver or lung; humans are accidental intermediate hosts after ingesting eggs from dog feces.
• Keywords: Hydatid cysts.

Schistosoma haematobium (Blood fluke)

• Feature: Blood fluke of urinary plexus; associated with painless hematuria and squamous cell carcinoma of the bladder.
• Keywords: Eggs have a terminal spine; endemic freshwater areas.

Schistosoma mansoni (Intestinal blood fluke)

• Feature: Causes bloody stool, portal hypertension, and hepatosplenic enlargement.
• Keywords: Large lateral-spined eggs.

Schistosoma japonicum (Oriental blood fluke)

• Feature: Produces severe hepatic fibrosis owing to high egg output.
• Keywords: Small lateral knob on egg; minute spine often difficult to see.

Fasciola hepatica (Sheep liver fluke)

• Feature: Acquired from aquatic plants (e.g., watercress); migrates through liver causing RUQ pain and biliary obstruction.
• Keywords: Large operculated eggs with shoulders.

Paragonimus westermani (Oriental lung fluke)

• Feature: Infection via raw crabs/crayfish, producing rusty (blood-tinged) sputum and pleuritic pain.
• Keywords: Golden-brown operculated eggs found in sputum or stool.

Clonorchis sinensis (Chinese liver fluke)

• Feature: Contracted by eating raw freshwater fish; causes biliary obstruction and risk of cholangiocarcinoma.
• Keywords: Small operculated eggs with shoulders.

Entamoeba histolytica (Protozoan amoeba)

• Feature: Causes amoebic dysentery and liver abscess; produces flask-shaped ulcers in colonic mucosa.
• Keywords: Trophozoites contain ingested red blood cells.

Giardia lamblia (Flagellated protozoan)

• Feature: Causes foul-smelling, greasy stools after ingesting contaminated water (often while camping).
• Keywords: Teardrop trophozoites bearing two nuclei (old-man face).

Cryptosporidium parvum (Coccidian parasite)

• Feature: Leads to profuse watery diarrhea, particularly severe and chronic in immunocompromised (e.g., AIDS) patients.
• Keywords: Oocysts are acid-fast.

Balantidium coli

• Feature: Largest intestinal protozoan and only ciliate infecting humans; zoonotic from pigs, causing bloody diarrhea.
• Keywords: Ciliated trophozoite with kidney-shaped macronucleus.

Isospora (Cystoisospora) belli (Coccidian parasite)

• Feature: Causes prolonged watery diarrhea in AIDS patients and other immunosuppressed hosts.
• Keywords: Acid-fast oval oocysts containing two sporocysts.