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Key Features

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Essentials of Diagnosis
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  • Mild abdominal pain; passage of worm segments (taeniasis)

  • Focal seizures, headaches (neurocysticercosis)

  • Cysticerci present in biopsy specimens, on plain radiographs (as calcified masses), or on CT scan or MRI

  • Proglottids and eggs in feces; specific antibodies in serum or cerebrospinal fluid (CSF)

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General Considerations
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  • Pigs are the usual intermediate host of the tapeworm Taenia solium

  • Human cysticercosis occurs when the eggs, which are excreted in the feces of a person infected with the parasite, are ingested

  • Cysticercosis cannot be acquired by eating pork

    • Ingestion of infected pork results in adult tapeworm infection (taeniasis) because infected pork contains the larval cysts that develop into the adult tapeworm

    • Infected pork does not contain the eggs that cause cysticercosis

  • Larvae released from ingested eggs enter the circulation to encyst in a variety of tissues, especially muscle and brain

  • Full larval maturation occurs in 2 months, but the cysts cause little inflammation until the larvae die months to years later

  • T solium and the beef tapeworm (Taenia saginata), which can cause taeniasis but not cysticercosis, are distributed worldwide

  • Contamination of foods by eggs in human feces allows person-to-person spread without exposure to meat or travel to endemic areas

  • Asymptomatic cases are common, but T solium is the most common helminth infection of the CNS and a leading cause of acquired epilepsy in the world

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Clinical Findings

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Symptoms and Signs
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  • Taeniasis

    • In most tapeworm infections, the only clinical manifestation is the passage of fecal proglottids, which are white, motile segments of tapeworm 1–2 cm in size

    • Children may harbor the adult worm for years and complain of abdominal pain, anorexia, and diarrhea

  • Cysticercosis

    • In the parenchymatous form, the parasite lodges in tissue as a single or multiple cysts

    • Seizures are caused by pericystic inflammation, which results from granuloma formation

    • Brain cysts may remain silent or cause seizures, headache, hydrocephalus, and basilar meningitis

    • A slowly expanding mass of sterile cysts at the base of the brain may cause obstructive hydrocephalus (racemose cysticercosis)

    • Rarely, the spinal cord is involved

    • Neurocysticercosis manifests an average of 5 years after exposure, but may cause symptoms in the first year of life

    • In the eyes, cysts cause bleeding, retinal detachment, and uveitis

    • The differential diagnosis of neurocysticercosis includes

      • Tuberculous granuloma

      • Microabscesses

      • Arachnoid cyst

      • Neoplasms

      • Vascular lesions

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Diagnosis

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Laboratory Findings
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  • Eggs or proglottids may be found in feces or on the perianal skin (using the tape method employed for pinworms)

    • Eggs of both Taenia species are identical

    • The species are identified by examination of proglottids

  • Peripheral eosinophilia is minimal or absent

  • CSF eosinophilia is seen in 10–75% of cases of neurocysticercosis; its presence supports an otherwise presumptive diagnosis

  • ELISA antibody titers are eventually positive in up to 98% of serum specimens and over 75% of ...

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