Clinical Parasitology Review Exam Flashcards

Comprehensive set of 400 vocabulary flashcards covering clinical parasitology review exam material, including protozoa, nematodes, trematodes, cestodes, diagnostic techniques, life cycles, and vectors.

Sarcoptes scabiei

A mite that creates tunnels through the upper layers of the skin, causing scabies and potentially generalized dermatitis in immunocompromised individuals; transmitted via person-to-person contact.

Sarcoptes scabiei Transmission

Direct person-to-person contact.

Kissing Bug (Triatomine Bug)

The vector that transmits Trypanosoma cruzi (the causative agent of Chagas' disease) in its feces, which is secondarily inoculated into the skin when the host scratches.

Chagas' Disease Etiology

Infection caused by the protozoan Trypanosoma cruzi, transmitted via the feces of kissing bugs (triatomine bugs) through skin abrasions caused by scratching.

Cysticercosis

Human infection caused by the larval stage of Taenia solium following the accidental ingestion of adult worm eggs.

Schistosoma mansoni Habitat

Resides as an adult worm primarily in the inferior mesenteric vein.

Schistosoma haematobium Habitat

Resides as an adult worm in the venous plexus draining the urinary bladder.

Anisakis

A fish nematode causing acute abdominal pain where the worm can be directly recovered or identified through endoscopy; humans serve as incidental hosts.

Dracunculus medinensis

Known as the "fiery serpent"; the female worm migrates to the skin surface of lower extremities creating blisters, where it emerges into water discharging larvae.

Miracidium

The free-swimming, ciliated trematode larval stage that hatches from an egg in freshwater and is capable of penetrating snail host tissue.

Clonorchis sinensis

The Chinese liver fluke linked to the development of cholangiocarcinoma; produces small, brown, operculated eggs with prominent shoulders and an abopercular knob.

Paragonimus westermani

The oriental lung fluke whose eggs feature a flattened operculum with prominent shoulders; isolated in stool and sputum specimens.

Capillaria philippinensis Egg Morphology

Peanut-shaped or football-shaped, colorless egg with striated shell and flattened bipolar mucus plugs.

Capillaria philippinensis ("Pudoc worm")

An intestinal nematode causing chronic diarrhea, gurgling stomach, abdominal pain, malabsorption, and steatorrhea; found in fish-eating birds and humans.

Giardia lamblia Trophozoite

A pear-shaped, bilaterally symmetrical protozoan featuring $4$ pairs of flagella and a ventral sucking disk, exhibiting classic falling-leaf motility.

Blastocystis hominis

An intestinal protozoan commonly seen in vacuolar form as spherical structures with multiple distinct nuclei located along the periphery.

Toxoplasma gondii Transmission Modes

Acquired through ingestion of oocysts shedding from felines or tissue cysts in undercooked meat, or via blood transfusion and transplacental transfer.

Leishmania

A flagellated tissue protozoan transmitted by sandflies that infects the reticuloendothelial system, taking on amastigote and promastigote developmental forms.

Definitive Host

The host in which a parasite reaches sexual maturity and undergoes sexual reproduction (e.g., fusion of male and female gametocytes resulting in an ookinete).

Malarial Thin Blood Film Inspection

Evaluates the appearance of infected RBCs, varieties of developmental parasite stages, and parasite morphology, but does NOT look for infected WBCs.

Hymenolepis nana Infective Stage

Embryonated egg.

Necator americanus Infective Stage

Filariform larva.

Taenia spp. Infective Stage for Humans (Tapeworm)

Cysticercus larva (found in undercooked meat).

Capillaria philippinensis Infective Stage

Infective larva (contained in undercooked fish).

Ascaris lumbricoides Adult Morphology

Cylindrical, pinkish worm measuring approximately $20\,cm$ in length and $6\,mm$ in diameter, possessing a buccal orifice with $3$ lips.

Diphyllobothriasis Anemia Type

Pernicious anemia (vitamin $B_{12}$ deficiency) caused by Diphyllobothrium latum, NOT iron deficiency anemia.

Diphyllobothrium latum Egg Characteristic

Operculated egg with a small terminal knob at the abopercular end.

Taenia saginata Alcohol Sensitivity

Taenia saginata proglottids and structures are characteristically sensitive to alcohol during laboratory processing.

Hymenolepis nana Life Cycle Uniqueness

The only human tapeworm that can complete its entire life cycle within a single host.

Trichuris trichiura Adult Shape

Resembles a whip, with an attenuated anterior whip-like region and a thick posterior body.

Diphyllobothrium latum First Intermediate Host

Cyclops (water flea).

Echinococcus granulosus Intermediate Host

Sheep and herbivores (humans act as accidental intermediate hosts).

Taenia solium Intermediate Host

Pigs (swine); humans act as intermediate host in cysticercosis.

Hymenolepis nana Intermediate Host

Insects (such as fleas or beetles) in its indirect cycle.

Chilomastix mesnili

A non-pathogenic intestinal flagellate; does NOT cause protracted diarrhea in AIDS patients.

Praziquantel

The drug of choice for treating tapeworm (cestode) and fluke (trematode) infections.

Buffy Coat

The thin layer of cells containing white blood cells and platelets formed between plasma and packed RBCs after centrifuging anticoagulated blood.

Hymenolepis diminuta Intermediate Host

Fleas (and beetles).

Hymenolepis Autoinfection

Occurs when eggs hatch and embryonate directly inside the intestinal lumen.

Dipylidium caninum Proglottid Morphology

Gravid proglottids resemble pumpkin seeds.

Filarial Diagnosis Blood Collection Timing

Dependent on the periodicity of the specific filarial parasite species (e.g., nocturnal vs. diurnal).

Onchocerca volvulus Diagnosis

Skin biopsy (skin snip examination), as microfilariae reside in skin tissue rather than circulating blood.

Wuchereria bancrofti Microfilaria Morphology

Sheathed microfilaria with a blunt rounded cephalic end and a tail tip free of nuclei.

Gravid

A parasitology term indicating a female worm or tapeworm proglottid filled with mature eggs (pregnant).

Balantidium coli Motility Organelle

Cilia.

Strongyloides stercoralis Opportunistic Pathogenicity

The primary nematode capable of hyperinfection and life-threatening dissemination in immunocompromised individuals.

Sabin-Feldman Dye Test

A classic serological test used specifically for the diagnosis of Toxoplasmosis.

Plasmodium falciparum Gametocyte Morphology

Crescent-shaped or banana-shaped gametocyte in stained blood films.

Cryptosporidium Staining Method

Modified acid-fast stain (oocysts stain reddish-purple), NOT standard Giemsa fecal smear.

Kato-Katz Technique Limitation

Hookworm eggs dissolve and disintegrate rapidly, so they cannot be well-preserved or accurately isolated if cleared too long.

Trichomonas vaginalis Motility in Urine

Exhibits characteristic jerky, tumbling motility.

Trichomonas vaginalis Diagnostic Methods

Includes wet mount demonstration of trophozoites, stained smears, and cultivation (culture is gold standard).

Giardia lamblia Lectins

Adhesion molecules produced by G. lamblia that are activated by duodenal secretions to facilitate attachment to host intestinal epithelial cells.

Trichomonas vaginalis Specimen Exception

Least likely to be found in stool specimens.

Dientamoeba fragilis Reclassification

Originally described as an amoeba due to ameboid movement, but structural analysis confirmed it is a flagellate.

Babesiosis Diagnosis

Demonstration of intraerythrocytic ring forms resembling Plasmodium falciparum in Giemsa-stained blood films.

S. japonicum Cercarial Production Limiting Factor

The physical size of the snail intermediate host.

Spurious Parasitism

Passage of non-human parasites or foreign eggs/larvae through the human GI tract after ingestion without causing infection.

Trematode Intermediate Host Requirement

All human trematodes (flukes) require $2$ intermediate hosts, EXCEPT Schistosomes (which require only $1$ snail host).

Paragonimus westermani Second Intermediate Host

Freshwater crabs (such as Sundathelphusa philippina).

Schistosomule

The immature fluke stage formed when a Schistosoma cercaria loses its forked tail upon penetrating human skin.

Clonorchiasis Prevention

Irradiating fish or thoroughly cooking freshwater fish.

Capillaria philippinensis Common Name

"Pudoc worm".

Dracunculus medinensis Common Name

"Fiery serpent".

Echinococcus granulosus Common Name

"Hydatid worm".

Cysticercus Common Name

"Bladder worm".

Echinostoma ilocanum Transmission

Acquired by ingesting infected freshwater snails (such as Susong pampang or Kuhol), NOT by eating fish.

Amoebiasis Confirmatory Diagnosis

Microscopic detection of Entamoeba histolytica trophozoites containing ingested red blood cells (erythrophagocytosis).

Amoebic Excystation Site

Transformation from cyst to trophozoite occurs in the small intestine.

Entamoeba coli Trophozoite Features

Blunt pseudopodia, sluggish undirected movement, vacuolated endoplasm containing ingested bacteria, and NO ingested RBCs.

Primary Amebic Meningoencephalitis (PAM)

A rapidly fatal brain infection caused by Naegleria fowleri penetrating the nasal mucosa and migrating via olfactory nerves.

Trichomoniasis Gold Standard Test

Culture.

Classical Malaria Paroxysm Stages

Consists of $3$ classic stages: Cold stage, Hot stage, and Sweating stage.

Plasmodium vivax & Plasmodium ovale Erythrocyte Preference

Preferentially infect young RBCs (reticulocytes).

Malaria Assessment Gold Standard

Stained thick and thin blood smears.

Plasmodium malariae Schizont Morphology

Contains $6\text{-}12$ merozoites (average $8\text{-}10$) arranged in a characteristic rosette form filling the host cell.

Plasmodium malariae Asexual Cycle Duration

$72\text{-hour}$ cycle (quartan periodicity).

Soil-Transmitted Helminths (STHs)

Intestinal nematodes requiring soil for larval development: Ascaris lumbricoides, Trichuris trichiura, Hookworms, and Strongyloides.

Kato-Katz Diagnostic Utility

Provides quantitative assessment of helminth infection intensity expressed in eggs per gram (EPG) of stool.

Ascaris lumbricoides Treatment Exclusion

Praziquantel is ineffective against Ascaris; broad-spectrum antihelminthics like Albendazole, Mebendazole, or Pyrantel pamoate are used.

Paragonimiasis Symptom Triad

Chest pain, chronic cough, and hemoptysis (coughing up blood).

Hookworm Body Site Migration

Includes skin, lungs, and small intestine; does NOT involve liver tissue.

Harada-Mori Technique

A filter paper culture method allowing hatching and recovery of hookworm or Strongyloides larvae in water.

Fasciola hepatica Target Organ

Human liver and biliary system.

WASHED Approach

Comprehensive STH control strategy in the Philippines: Water, Sanitation, Hygiene, Education, and Deworming.

Parthenogenesis in Parasitology

A reproductive process seen in female Strongyloides stercoralis where eggs develop without fertilization by male worms.

Cochin China Diarrhea

Intractable, painless, intermittent watery and bloody diarrhea seen in heavy Strongyloides stercoralis hyperinfections.

Enterobius vermicularis Egg Shape

Asymmetrical egg with one side flattened and the other side convex.

Katayama Fever

An acute serum-sickness-like syndrome caused by Schistosoma japonicum infection, characterized by fever, fatigue, systemic malaise, and abdominal symptoms.

Microfilaria

The larval stage of filarial worms circulating in peripheral blood that is ingested by mosquito vectors during a blood meal.

Taenia saginata Oncosphere

Hexacanth larva released from Taenia saginata eggs when ingested by cattle.

Human Cysticercosis Cause

Infection with the larval stage of Taenia solium following ingestion of eggs.

Hymenolepis nana Indirect Life Cycle Route

Accidental ingestion of infected insect intermediate hosts containing cysticercoids.

Heterophyids Mode of Transmission

Ingestion of raw or undercooked fish carrying metacercariae.

Schistosoma Cercarial Release Timing

S. haematobium and S. mansoni usually release cercariae into water naturally during daytime or specific light intervals.

Fasciola gigantica Egg Similarity

Morphologically almost identical to Fasciola hepatica and Fasciolopsis buski eggs.

Taenia saginata Identification Procedure

Saline wet mount examination of proglottids or scotch tape perianal swab.

Enterobius vermicularis Isolation Forms

Adult female worms and eggs isolated from the perianal area using cellulose scotch tape.

Hookworm vs. Strongyloides stercoralis Larval Differentiation

As illustrated in the comparative diagram, Hookworm rhabditiform larva features a long buccal cavity, small genital primordium, short esophagus, and pointed tail. Strongyloides stercoralis rhabditiform larva features a short buccal cavity, large genital primordium, long esophagus, and notched tail.

Viviparous Intestinal Nematode

Trichinella spiralis (bears live larvae directly rather than laying eggs).