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# Cestodes (tapeworms)

- Parasites

Flat, segmented worms with no gut. Humans can host the adult tapeworm in the bowel or, worse, its larva in tissues.

Updated 2026-11-01

## What they are

Cestodes are ribbon-shaped flatworms made of a scolex that attaches to the gut and a chain of segments (proglottids). They absorb nutrients through their surface. Serious disease appears when the human acts as intermediate host and the larva forms cysts in tissues.

## What they share

- Ribbon body: scolex, neck and proglottids.
- No gut; nutrients absorbed through the tegument.
- Hermaphroditic.
- Cycles with an intermediate host (pig, cattle, dog, fish), except Hymenolepis nana.

## Key points

- An adult tapeworm in the gut causes few symptoms; the larva in tissues (cysticercus, hydatid) causes serious disease.
- Cysticercosis: T. solium eggs; hydatid disease: Echinococcus eggs from dogs.
- Praziquantel for intestinal tapeworms; albendazole for tissue cysts.
- Dibothriocephalus latus: vitamin B12 deficiency.

## Microorganisms in this group

- [**Taenia solium** Pork tapeworm. Undercooked pork gives the gut tapeworm; swallowing its eggs puts cysts in the brain (neurocysticercosis), a major cause of epilepsy. Exam priority: high](https://durgical.com/en/microbiology/taenia-solium/)
- [**Taenia saginata** The beef tapeworm. It lives for years in the gut and causes few symptoms; unlike the pork tapeworm, it does not cause cysts in humans. Exam priority: medium](https://durgical.com/en/microbiology/taenia-saginata/)
- [**Echinococcus granulosus** A tiny dog tapeworm. If a person swallows its eggs, cysts grow for years in the liver or lung (hydatid disease). Exam priority: medium](https://durgical.com/en/microbiology/echinococcus-granulosus/)
- [**Hymenolepis nana** The smallest and commonest tapeworm in children. It passes from person to person without another animal and can reinfect the same child from within. Exam priority: medium](https://durgical.com/en/microbiology/hymenolepis-nana/)
- [**Dibothriocephalus latus** The longest human tapeworm; it comes from raw or undercooked fish. It can steal vitamin B12 and cause megaloblastic anaemia. For completeness](https://durgical.com/en/microbiology/dibothriocephalus-latus/)

## Test yourself

Think of the answer, then tap the question to see it.

## When does a cestode cause serious disease in humans?

When the human acts as intermediate host and the larva forms tissue cysts, as in cysticercosis or hydatid disease.

## Which cestode needs no intermediate host?

Hymenolepis nana.

## Which drug is used for most intestinal tapeworms?

Praziquantel.

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Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [CDC - DPDx - Taeniasis](https://www.cdc.gov/dpdx/taeniasis/index.html) (CDC, 2024); [Taeniasis/cysticercosis](https://www.who.int/news-room/fact-sheets/detail/taeniasis-cysticercosis) (WHO, 2022); [Echinococcosis](https://www.who.int/news-room/fact-sheets/detail/echinococcosis) (WHO, 2021).

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Representative model, for educational purposes only.

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