Medical Parasitology Lecture and Exam Review

Vocabulary practice flashcards covering medical parasitology, including parasite biology, clinical features, vectors, hosts, diagnostics, and pharmacological treatments.

Definitive Host

The host in which a parasite undergoes sexual reproduction or reaches maturity, harboring the adult stage (or both sexual and asexual stages in certain protozoa).

Intermediate Host

A host that harbors the larval, asexual, or developmental stages of a parasite.

Paratenic Host

A transport host in which a parasite survives and remains viable without undergoing development.

Facultative Parasite

An organism that can survive and reproduce freely in the environment or live parasitically within a host.

Obligate Parasite

An organism that completely depends on a host to survive and complete its life cycle.

Ectoparasite

A parasite that lives and feeds on the outer surface of its host.

Intracellular Parasite

A parasite that invades and lives inside host cells.

Commensalism

A symbiotic relationship in which one organism benefits while the other organism is unaffected.

Zoonosis

An infectious disease that is naturally transmissible from vertebrate animals to humans.

Parasite Virulence

The measure of pathogenicity reflecting the severity of disease caused by a parasite.

Parasite Intensity

The total number of individual parasites inhabiting an infected host.

Entamoeba histolytica

An invasive intestinal amoeba moving by pseudopodia that causes amoebic dysentery and extraintestinal amoebic liver abscess; diagnosed via cysts and trophozoites in stool.

Giardia lamblia

A flagellated intestinal protozoan with bilateral symmetry and a ventral sucker disc that colonizes the small intestine, causing malabsorption of fats and foul-smelling steatorrhea.

Balantidium coli

The only ciliate protozoan known to infect humans; commonly associated with pigs and localized in the colon, causing dysentery with bloody and mucoid stool.

Trichomonas vaginalis

A sexually transmitted flagellated protozoan that exists exclusively in the trophozoite form (lacking a cyst stage) and is diagnosed by wet mount examination of vaginal discharge.

Toxoplasma gondii

A tissue-dwelling apicomplexan protozoan whose definitive hosts are felines (cats); dangerous for pregnant women and immunocompromised hosts due to congenital transmission and brain abscess formation.

Babesia microti

A tick-borne blood protozoan transmitted by Ixodes ticks that infects erythrocytes to form tetrads (Maltese cross appearance) without producing hemozoin pigment.

Cryptosporidium parvum

An intestinal coccidian parasite protected by a thick outer oocyst wall that provides high resistance to chlorine disinfection in municipal water and swimming pools.

Plasmodium falciparum

The most dangerous malaria species, capable of causing severe complications and characterized microscopically by crescent-shaped gametocytes and Maurer's dots.

Plasmodium vivax

A malaria parasite causing benign tertian fever (every $48\,\text{hours}$) and enlargement of infected red blood cells; forms dormant hypnozoites in liver hepatocytes.

Plasmodium malariae

A malaria species characterized by a quartan fever cycle (every $72\,\text{hours}$) and typical band-form trophozoites across infected erythrocytes.

Hypnozoite

The dormant, intrahepatic stage formed by Plasmodium vivax and Plasmodium ovale responsible for late clinical relapses.

Thick Blood Film

A diagnostic blood preparation primarily used for detecting low-level parasitemia and establishing parasite presence in suspected malaria.

Thin Blood Film

A fixed blood smear used to observe red blood cell morphology and specifically identify Plasmodium species.

Schistosoma spp.

Blood flukes with separate male and female sexes that infect humans via cercarial skin penetration from infested freshwater containing intermediate host snails; non-operculated eggs.

Schistosoma haematobium

A blood fluke depositing eggs in the venules of the urinary bladder plexus, causing hematuria and predisposing patients to squamous cell bladder carcinoma.

Schistosoma mansoni

A schistosome species whose large, oval eggs are identified by a prominent lateral spine.

Clonorchis sinensis

The Chinese liver fluke, acquired by ingesting undercooked freshwater fish harboring metacercariae, which inhabits the bile ducts and produces operculated eggs with a terminal knob.

Fasciola hepatica

The sheep liver fluke that resides in the biliary system following ingestion of metacercariae on raw freshwater plants (such as watercress); treated with triclabendazole.

Fasciolopsis buski

The largest intestinal trematode of humans, acquired by eating raw aquatic plants (such as water chestnuts) and causing severe intestinal obstruction in heavy infestations.

Paragonimus westermani

The lung fluke, acquired from raw or undercooked crabs or crayfish, which localizes in the lungs producing pulmonary disease mimicking tuberculosis; eggs are found in sputum and stool.

Taenia solium

The pork tapeworm whose scolex possesses four suckers and hooks; human ingestion of cysticerci in undercooked pork causes taeniasis, while ingestion of eggs causes cysticercosis.

Taenia saginata

The beef tapeworm, acquired by eating raw or undercooked beef containing cysticerci, identified by a scolex without hooks and proglottids containing 15 to 30 lateral uterine branches.

Neurocysticercosis

A severe central nervous system pathology resulting from the development of Taenia solium larval cysts (cysticerci) in the brain after egg ingestion.

Diphyllobothrium latum

The broad fish tapeworm that requires two intermediate hosts and causes megaloblastic anemia via competitive depletion of host vitamin $B_{12}$.

Echinococcus granulosus

The dog tapeworm whose accidentally ingested eggs develop into slowly expanding hydatid cysts, most commonly located in the human liver.

Hymenolepis nana

The dwarf tapeworm, unique among cestodes for completing its entire life cycle within a single host without requiring an obligatory intermediate host; eggs have polar filaments.

Ascaris lumbricoides

A large human intestinal roundworm acquired by ingesting embryonated eggs from contaminated soil, capable of causing mechanical intestinal obstruction in high-worm burdens.

Trichuris trichiura

The whipworm, characterized by barrel-shaped eggs with prominent bipolar plugs; heavy juvenile infections can lead to chronic bloody diarrhea and rectal prolapse.

Ancylostoma duodenale

An Old World hookworm whose filariform (L3) larvae penetrate intact human skin (causing ground itch) and adult worms feed on mucosal blood, resulting in iron-deficiency anemia.

Strongyloides stercoralis

An intestinal nematode capable of internal autoinfection, predisposing immunocompromised hosts to life-threatening hyperinfection syndrome; diagnosed by finding rhabditiform larvae in stool.

Enterobius vermicularis

The pinworm, which exhibits no visceral tissue migration and causes nocturnal perianal pruritus; diagnosed using a cellophane tape test applied in the early morning.

Trichinella spiralis

A parasitic roundworm acquired from raw or undercooked pork whose released larvae migrate and encyst directly within striated skeletal muscle, diagnosed by muscle biopsy.

Anisakis spp.

A marine nematode acquired by consuming raw seafood that invades the gastric or intestinal mucosa, triggering acute gastrointestinal symptoms and eosinophilic granulomas.

Dracunculus medinensis

The guinea worm, transmitted through ingestion of stagnant water containing copepods (Cyclops); adult female worms emerge through subcutaneous blisters and are extracted by winding around a stick.

Wuchereria bancrofti

A mosquito-borne filarial nematode that localizes within human lymphatic vessels, leading over time to chronic lymphatic obstruction and elephantiasis.

Praziquantel

An anthelmintic agent that serves as the drug of choice for treating schistosomiasis, clonorchiasis, and adult tapeworm infections (taeniasis).

Ivermectin

The first-line drug of choice for the treatment and control of strongyloidiasis.

Metronidazole

The primary therapeutic agent prescribed for anaerobic protozoan infections, including Trichomonas vaginalis, Giardia lamblia, and invasive Entamoeba histolytica.

Mebendazole

A broad-spectrum benzimidazole anthelmintic commonly used to treat nematode infections including Ascaris lumbricoides and Trichuris trichiura.