cysticercosis

Introduction

Human infection with the larval stage of the pork tapeworm Taenia solium.

Etiology

• ingestion of eggs from the adult form of Taenia solium
  • eggs found in contaminated food or water, especially vegetables grown in soil fertilized by pig excrement
  • eggs may be ingested from adult worm infecting host via oral-fecal route
• eggs hatch in gastrointestinal tract
• embryos penetrate intestinal mucosa & disseminate via the blood stream
• muscle, heart, brain & eye are sites where infection becomes apparent
• ingestion of adult worm from undercooked pork containing cysticerci causes intestinal infection

Epidemiology

• prevalent in:
  • Latin America, including Mexico
  • Europe, especially eastern Europe
  • Pakistan
  • India
  • China
  • Africa
• one of top 5 neglected parasitic infections in the U.S.
  • > 1000 hospitalizations annually

Pathology

• symptoms are often produced when the organism dies, which evokes an inflammatory response

Clinical manifestations

• infection with adult tapeworm
  • abdominal discomfort
  • diarrhea
• cysticercosis
  • symptoms produced by:
    • local inflammatory response
    • space-occupying lesions
  • neurologic manifestations
    • seizures* - generalized, focal & Jacksonian
    • signs of increased intracranial pressure*
    • focal neurologic deficits
    • meningitis
    • hydrocephalus (communicating & non-communicating)

* most common presentations

Laboratory

• biopsy: see Taenia solium (image)
• serology
  • Taenia solium serology
    • Taenia solium antibody in CSF
    • Taenia solium antibody in serum
  • glycoprotein immunoblot assay available from CDC
    • best sensitivity & specificity
  • enzyme immunoassay (EIA)
  • indirect hemagglutination (IHB)
  • serologic assays do not distinguish active from inactive infection
  • not useful in monitoring response to therapy
• stool examination for eggs
  • eggs spherical 31-43 um in diameter
  • egg shell is thick striated & contains a 6-hooked embryo
  • eggs from Taenia species are indistinguishable
• CSF examination
  • pleocytosis with predominance of mononuclear cells
  • glucose generally decreased
  • protein generally elevated
  • CSF serology helpful for diagnosis of neurocysticercosis
• Taenia solium antigen in stool
• Taenia solium larva DNA in CSF
• Strongyloides stercoralis serology in patients likely to require prolonged glucocorticoids*
• see ARUP consult

* empiric therapy for Strongyloides stercoralis is also acceptable

Diagnostic procedures

• screening for latent tuberculosis in patients likely to require prolonged glucocorticoids
• funduscopic examination before initiation of anti-helminthic therapy

Radiology

• plain films may show calcified lesions
• CT of head may show multiple calcified &/or non calcified cystic lesions
• brain MRI may show multiple enhancing cystic lesions (enhancing with gadolinium)
  • indicated even if CT of head shows calcified lesions in brain parenchyma
  • repeat brain MRI every 6 months until resolution of cysts
  • MRI image: see ref
• both brain MRI with contrast & non-contrast brain CT recommended

* intracranial calcification generally occurs 5-20 years after exposure

Differential diagnosis

• toxoplasmosis

Management

• management of elevated intracranial pressure prior to anti-helminthic therapy
• intestinal Taenia solium infection
  • praziquantel 5-10 mg/kg
• cysticercosis
  • asymptomatic patients do not require therapy
  • symptomatic patients with neurocysticercosis
    • albendazole, praziquantel & dexamethasone
      • albendazole 15 mg/kg/day divided TID for 10-14 days
        • Americian Academy of Neurology recommends albendazole
      • praziquantel 50 mg/kg/day divided TID for 10-14 days
      • both agents induce inflammatory response surrounding dying organisms
      • high-dose glucocorticoids (dexamethasone or prednisolone) to accompany praziquantel &/or albendzole
        • especially if evidence of spinal cord dysfunction (paraparesis, incontinence)
    • hospitalize during treatment
    • therapy monitored by radiographic imaging
      • active lesions should decrease in size within 3-6 months
    • anticonvulsants until the active lesions have diminished may be prudent
  • surgical resection indicated for patients with:
    • eye lesions
    • spinal cord lesions
    • cystic lesions in the ventricles
    • drug therapy-induced inflammation may result in irreversible damage
• anticonvulsants for patients with seizures & single enhancing brain lesions
  • anticonvulsant may be stopped with resolution of enhancing brain lesion & seizures for 6 months
• contacts
  • consider screening household members
  • local health department may be of assistance

More general terms

• helminth infection

More specific terms

• neurocysticercosis

Additional terms

• Taenia solium (pork tapeworm, cysticercus)