Correct Answer: D. Cysticercosis cellulosae
Cysticercosis cellulosae is the larval stage of Taenia solium (pork tapeworm) that develops in human tissues, particularly the brain, causing neurocysticercosis—the most common parasitic cause of seizures in India. When humans ingest T. solium eggs (through fecal-contaminated food/water), the eggs hatch in the small intestine and penetrate the intestinal wall, disseminating via blood to various tissues including the CNS. The larvae form cysts in brain parenchyma, which trigger seizures through inflammation, mass effect, and calcification. MRI typically shows multiple cystic lesions with surrounding edema in the brain parenchyma, which is pathognomonic for neurocysticercosis. The disease is endemic in India due to poor sanitation, consumption of undercooked pork, and lack of meat inspection. Diagnosis is confirmed by serology (ELISA for T. solium antibodies), imaging findings, and clinical presentation of seizures. This is the only option that represents the larval form infecting humans and causing CNS disease.
Why the other options are wrong
A. T. saginata — Taenia saginata (beef tapeworm) is the adult tapeworm acquired by eating undercooked beef. It does NOT form larvae in human tissues and does NOT cause cysticercosis or seizures. It remains in the intestinal lumen causing malabsorption and anemia, not neurological disease. This is a distractor testing knowledge of tapeworm species differentiation. B. Cysticerocosis bovis — Cysticercosis bovis is the larval stage of T. saginata that develops in cattle (intermediate host), not in humans. Humans cannot develop cysticercosis bovis; this term refers to the disease in cattle. This is a terminology trap—students may confuse larval forms across different tapeworm species. C. T. asiatica — Taenia asiatica is a recently identified tapeworm endemic in Southeast Asia (Thailand, Vietnam, Laos) transmitted through undercooked freshwater fish. It does not cause cysticercosis in humans and is rare in India. The adult worm causes intestinal disease, not CNS involvement or seizures.
High-Yield Facts
- Neurocysticercosis is the most common parasitic cause of seizures in India and endemic regions with poor sanitation.
- Cysticercosis cellulosae is the larval stage of Taenia solium that develops in human tissues (brain, muscle, subcutaneous) after ingestion of eggs.
- MRI findings in neurocysticercosis show multiple cystic lesions with surrounding edema, calcifications, and mass effect in brain parenchyma.
- Transmission occurs via fecal-contaminated food/water (eggs), not through eating infected meat; adult tapeworm is acquired by eating undercooked pork.
- Serology (ELISA) and imaging are diagnostic; treatment includes albendazole/praziquantel with corticosteroids to manage inflammation.
Mnemonics
Tapeworm Species & Disease in Humans T. solium → Cysticercosis (larvae in tissues, seizures) | T. saginata → Intestinal tapeworm only (no cysticercosis) | T. asiatica → Fish-borne, rare in India. Remember: Only solium causes human cysticercosis. Neurocysticercosis Trigger SEIZURES + MRI cysts in brain = Think T. solium cysticercosis until proven otherwise in Indian endemic areas. Fecal-oral route (eggs), not meat consumption.
NBE Trap
NBE pairs tapeworm species names to confuse students: T. saginata causes intestinal disease (no cysticercosis), while T. solium causes cysticercosis. Students may incorrectly choose T. saginata if they remember "tapeworm" without distinguishing larval vs. adult forms and tissue tropism.
Clinical Pearl
In Indian clinical practice, any patient presenting with new-onset seizures and MRI showing multiple brain cysts should raise suspicion for neurocysticercosis—it is far more common than idiopathic epilepsy in endemic areas. Serology and imaging confirmation are essential before starting anthelmintic therapy, as killing cysts can trigger severe inflammation and status epilepticus.
_Reference: Jawetz, Melnick & Adelberg's Medical Microbiology Ch. 45 (Cestodes); Park's Textbook of Preventive & Social Medicine Ch. 7 (Parasitic Infections)_