Class Trematoda - Flukes Lecture Notes

A set of vocabulary flashcards covering general trematode morphology, classification, species-specific characteristics, and diseases based on the lecture material.

Class Trematoda

A class of flat, unsegmented, leaf-like worms commonly known as flukes, which are among the most common parasitic worms second only to nematodes.

Digenetic flukes

Trematodes whose life cycle involves at least two hosts and complex larval stages.

Oral sucker

A structure located at the anterior end of a fluke used for nourishment.

Acetabulum

Also known as the ventral sucker, this structure is used by trematodes for attachment to their host.

Hermaphrodites

Organisms that possess both male and female reproductive systems; most flukes fit this description except for the genus Schistosoma.

Schistosoma

A genus of flukes known as blood flukes that are dioecious (separate sexes), non-operculated, and do not have a metacercaria stage.

Metacercaria

The encysted larval stage of trematodes that serves as the infective stage for the definitive host, except in Schistosoma.

Miracidium

The free-swimming ciliated larval stage that hatches from the egg and penetrates the first intermediate host.

Schistosoma japonicum

The "oriental blood fluke" inhabiting the portal bloodstream, characterized by nontuberculate integument and a uterus containing $50-100$ eggs at a time.

Schistosoma mansoni

The "intestinal blood fluke" found in Africa and the Western Hemisphere, characterized by a long lateral spine on its eggs.

Schistosoma haematobium

The "urinary blood fluke" found in Africa and the Middle East, characterized by eggs with a terminal spine and an association with bladder cancer.

Katayama fever

A clinical feature specifically associated with Schistosoma japonicum infection.

Fasciola hepatica

The "sheep liver fluke" that causes liver rot and is acquired by humans through the ingestion of metacercaria on water plants like watercress.

Cephalic cone

A structure at the anterior end of Fasciola hepatica giving it a distinct shouldered appearance.

Halzoun

A pharyngeal disease causing pain and bleeding, resulting from the ingestion of raw animal liver infected with adult Fasciola worms.

Fasciola gigantica

The "giant liver fluke" of herbivores, which is longer and more slender than F. hepatica, reaching up to $7.4\,cm$ in length.

Clonorchis sinensis

The "Chinese liver fluke" whose adults reside in the bile ducts and whose flask-shaped eggs have a small terminal knob.

Opisthorchis viverrini

The "Southeast Asian liver fluke," highly prevalent in Thailand and Laos and significantly correlated with the incidence of cholangiocarcinoma.

Opisthorchis felineus

The "cat liver fluke," common in Europe and Siberia, with morphology similar to C. sinensis but with narrower eggs.

Dicrocoelium dendriticum

The "lancet liver fluke" which uses the common brown ant (Formica fusca) as a second intermediate host; it is known as a "brainworm" for altering ant behavior.

Fasciolopsis buski

The "giant intestinal fluke," the largest fluke infecting humans, which causes malabsorption and intestinal obstruction.

Echinostoma ilocanum

An intestinal fluke common in the Philippines characterized by a crown of $49-51$ circumoral spines.

Heterophyids

A group of minute, teardrop-shaped flukes ($1-2.5\,mm$) found in the small intestine of fish-eating birds and mammals.

Paragonimus westermani

The "oriental lung fluke" that forms cystic structures in the lungs, producing golden-brown eggs typically found in the sputum.

Charcot-Leyden crystals

Diamond-shaped crystals found in the sputum of patients infected with Paragonimus westermani.

Cercaria

The larval stage of a trematode that is released from the snail (1st intermediate host); it often has a tail for swimming.

Lymnaea truncatula

The first intermediate snail host for Fasciola hepatica.

Gynecophoral canal

A groove in the body of the male Schistosoma worm where the female resides.

Praziquantel

A primary drug treatment used for most trematode infections including Schistosomiasis, Clonorchiasis, and Paragonimiasis.