Question
Cysticercus cellulosae
Answer
Cysticercus cellulosae: the larval (metacestode/bladder-worm) stage of the tapeworm Taenia solium, causing cysticercosis in humans (who act as an accidental intermediate host when the eggs are ingested).
Structure: a small, translucent, fluid-filled cyst (approximately 0.5–1.5 cm), containing a single inverted, invaginated scolex with the characteristic hooklets and suckers of T. solium.
Sites of localization: subcutaneous tissue, skeletal muscle, brain (causing neurocysticercosis — the most clinically significant site, a leading cause of acquired epilepsy in endemic regions, presenting with seizures and multiple ring-enhancing lesions on neuroimaging), and the eye.
Life cycle relevance: acquired by ingestion of T. solium eggs (via faeco-oral contamination or autoinfection from an intestinal tapeworm carrier), distinct from ingestion of the cysticercus itself in undercooked pork (which instead causes adult intestinal tapeworm infection/taeniasis).
Diagnosis: neuroimaging (CT/MRI) showing characteristic ring-enhancing lesions with a visible scolex; serology (ELISA/immunoblot for anti-cysticercal antibody); and, for calcified/dead cysts, characteristic radiographic (“rice-grain”) calcifications in muscle.
Treatment: Albendazole/Praziquantel, generally combined with corticosteroids to control the inflammatory response to dying cysts, and anticonvulsants for seizure control.