Cestoda Flashcards

Class Cestoda Overview

• Belongs to the Kingdom Animalia and Phylum Platyhelminthes.
• All cestodes are obligate parasites, requiring at least one intermediate host.

General Characteristics

• Cestodes have a solid, flattened body structure.
• They lack an anus and possess a body filled with parenchyma.
• Hermaphroditic, with a simple muscular, digestive, and nervous system.
• Reproductive tracts are well-developed.

Tapeworm Structure

• Adult tapeworms range from a few millimeters to several meters in length.
• Composed of three main parts: scolex, neck, and strobila.
• Scolex serves for attachment and locomotion, often featuring hooks and suckers.
• The neck connects the scolex and strobila, containing embryonated cells that generate new segments.
• The strobila consists of proglottids, maturing as they progress along its length.

Proglottids

• Contain genital organs, filled with thousands of eggs after fertilization.

Tegumentum

• The outer coating of tapeworms, replaced every 6-8 hours.
• Most metabolic processes occur through this layer.

Life Cycle

• Life cycle involves proglottids/eggs in stool, egg ingestion by intermediate host, maturation to larval form, ingestion by definitive host, and migration to intestines.

Family Taenidae

• Features two rows of hooks and a single genitalia on proglottis.
• Proglottids have trapezoidal, serrated segments.

Taenia Eggs

• Rounded to oval with a thick, radiating outer membrane often containing hooks.

Taenia Species Impact

• Dogs: Taenia pisiformis (rodents), Taenia hydantigena (rabbits), Taenia ovis (sheep), Multiceps multiceps (rodents), Echinococcus granulosus.
• Cats: Taenia taeniaformis (rodents), Echinococcus multiocularis (rodents).

Prepatent Periods

• Taenia pisiformis: 1-2 months.
• Dipylidium caninum: 2-3 weeks.

Host Information

• Intermediate hosts for Taenia in dogs include prey animals, while in cats, they are typically mice and rats.
• Echinococcus granulosus has zoonotic transmission routes, utilizing dogs as definitive hosts and sheep or goats as intermediate hosts.

Health Impact in Humans

• Echinococcus granulosus can inhabit the liver, lungs, and brain in humans, with dogs carrying them primarily in the liver and lungs.

Family Dilepididae

• Known as the most common tapeworm family in dogs and cats, with Dipylidium caninum being the most prevalent species.
• Intermediate hosts for Dipylidium caninum are fleas (Ctenocephalides felis) and lice (Felicola, Trichodectes).

Diagnosis and Treatment

• Diagnosis involves visual inspection of proglottids in feces and possible fecal flotation.
• Clinical signs of tapeworms include abdominal discomfort, anorexia, pruritus, and possible intestinal irritation.
• Treatments include praziquantel, fenbendazole, and epsiprantel, along with preventive measures like flea control and discouraging hunting behavior.