DurgicalDurgical
EN
Open the app

Microbiology · Cestodes (tapeworms)

Taenia solium !

  • Parasite
  • Exam priority: high

Pork tapeworm. Undercooked pork gives the gut tapeworm; swallowing its eggs puts cysts in the brain (neurocysticercosis), a major cause of epilepsy.

Updated 2026-11-01

Also called: pork tapeworm, cysticercus

At a glance

Shape
Scolex with 4 suckers and a rostellum with a double crown of hooks (armed)
Family
Taeniidae
Type
Cestode (flatworm); humans can host the adult or the larva
Size
Adult 2–7 m; cysticercus 0.5–2 cm

Morphology

  • Gravid proglottid with 7–13 lateral uterine branches (the key to telling it from T. saginata).
  • Spherical egg with a radially striated embryophore and a six-hooked oncosphere; identical to T. saginata and similar to Echinococcus.
  • Cysticercus: a fluid-filled vesicle with an invaginated scolex (the 'dot' seen on MRI).

Transmission

  • Eating raw or undercooked pork with cysticerci → taeniasis (adult tapeworm in the gut).
  • Swallowing eggs shed by a human carrier (hands, food, water) → cysticercosis; the carrier is often in the same household.
  • Autoinfection of the carrier by the anus-hand-mouth route.

Reservoir: Humans are the only definitive host; Pigs as the usual intermediate host

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Life cycle

  1. The human carrier passes gravid proglottids and eggs in stool; the eggs are infective at once.
  2. A pig (or a person) swallows the eggs; the oncosphere hatches in the gut and invades the wall.
  3. Through the blood it reaches muscle, brain, eye and subcutaneous tissue and forms cysticerci in about 60–70 days.
  4. A person who eats undercooked pork with cysticerci releases the scolex, which attaches to the small bowel.
  5. In about 2 months the adult tapeworm matures and starts shedding proglottids: the cycle closes.
  6. A human who swallows eggs becomes an accidental intermediate host: that is cysticercosis.

Virulence factors

  • While alive, the cysticercus dampens the immune response and often goes unnoticed.
  • When the cyst degenerates, inflammation of the surrounding tissue triggers seizures and oedema.
  • Ventricular or subarachnoid (racemose) cysts block CSF flow and cause hydrocephalus.
  • The adult tapeworm causes few symptoms but makes the carrier an egg source for everyone nearby.

Diseases it causes

Clinical picture

  • First seizure in a young adult from an endemic rural area.
  • Headache, vomiting and papilloedema from hydrocephalus.
  • Ocular cysticercosis or subcutaneous nodules.
  • Symptoms may start months or years after infection, when the cyst begins to die.

Diagnosis

  • Neuroimaging: MRI shows cysts with a scolex; CT is better for calcifications.
  • Immunoblot (EITB) with T. solium antigens in serum or CSF to confirm; it does not separate active from inactive infection.
  • Carrier: eggs or proglottids in stool; the number of uterine branches identifies the species.
  • Fundoscopy before antiparasitic treatment to rule out eye cysts.

Treatment

Taeniasis: praziquantel or niclosamide. Neurocysticercosis: antiparasitics (albendazole, sometimes with praziquantel) only when cysts are viable, always with corticosteroids and antiseizure drugs; hydrocephalus needs surgery or a shunt, and calcified lesions get no antiparasitic.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

Prevention

  • Cook pork thoroughly and strengthen meat inspection.
  • Find and treat tapeworm carriers and their households.
  • Handwashing, latrines and an end to open defecation.
  • Penned pig rearing with pig deworming and vaccination (One Health).

Test yourself

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

How is neurocysticercosis acquired?

By swallowing T. solium eggs shed by a human tapeworm carrier (contaminated hands, food or water), not by eating pork.

Which MRI finding suggests a viable cysticercus?

A cyst with an eccentric dot inside it: the scolex.

Why are corticosteroids given with albendazole in neurocysticercosis?

Because dying cysts cause inflammation and oedema that can worsen seizures or intracranial pressure.

Which test confirms cysticercosis serology?

The immunoblot (EITB) with T. solium antigens, in serum or CSF.

Which proglottid feature separates T. solium from T. saginata?

T. solium has 7–13 uterine branches per side; T. saginata has 12–30.

Add to my cards (5)

← Back to the group: Cestodes (tapeworms)

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

Sources: CDC - DPDx - Cysticercosis (CDC, 2019); CDC - DPDx - Taeniasis (CDC, 2024); Taeniasis/cysticercosis (WHO, 2022); About Cysticercosis | Cysticercosis | CDC (CDC, 2024).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.