Cysticercosis - Taenia Solium

Cysticercosis is a parasitic infection caused by the larval stage of the pork tapeworm, Taenia solium. Diagnosis usually involves both serological testing and brain imaging.

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Clinical Overview

Diagnosis

Indications for Testing

Seizures or hydrocephalus not caused by common etiologies
Calcitic cysts on CT scan

Criteria for Diagnosis

Absolute criteria
- Demonstration of cysticerci by histologic or microscopic examination of biopsy materials
- Visualization of the parasite in the eye by funduscopy
- Neuroradiologic demonstration of cystic lesions containing a characteristic scolex
Major criteria
- Neuroradiologic lesions suggestive of neurocysticercosis
- Demonstration of antibodies to cysticerci in serum by enzyme-linked immunoelectrotransfer blot
- Resolution of intracranial cystic lesions spontaneously or after therapy with albendazole or praziquantel alone
Minor criteria
- Lesions compatible with neurocysticercosis detected by neuroimaging studies
- Clinical manifestations suggestive of neurocysticercosis
- Demonstration of antibodies to cysticerci or cysticercal antigen in cerebrospinal fluid (CSF) by ELISA
- Evidence of cysticercosis outside the central nervous system (eg, cigar-shaped soft-tissue calcifications)
Epidemiologic criteria
- Residence in a cysticercosis-endemic area
- Frequent travel to a cysticercosis-endemic area
- Household contact with an individual infected with Taenia solium
Key for diagnostic interpretation
- Confirmation
  - One absolute criterion
  - Two major, one minor, and one epidemiologic criteria
- Probable
  - One major and two minor criteria
  - One major, one minor, and one epidemiologic criteria
  - Three minor and one epidemiologic criteria

Laboratory Testing

CDC cysticercosis resources for health professionals and diagnosis recommendations
Testing for consensus criteria
- CSF antibody by ELISA with confirmation by Western blot
- Serology – limited diagnostic use as a single test (variable sensitivity/specificity)
  - May be useful if used with imaging data
    - ELISA as initial testing in either serum or CSF
    - Confirm ELISA with Western blot – more sensitive (available at some laboratories; not currently available at ARUP Laboratories)

Imaging Studies

Diagnosis is most often made by MRI or CT brain scans; addition of serologic screening by ELISA with confirmation by Western blot increases sensitivity of diagnosis of cysticercosis
- CT scan – high sensitivity and specificity; lower for ventricular or cisternal forms
  - Single or multiple rounded lesions of low density with a small hyperdense mural nodule representing the scolex (starry night appearance)
- MRI – more sensitive than CT; much more expensive

Differential Diagnosis

Vasculitis
Central nervous system tumor
Seizure disorders
Stroke
Infection
- Mycobacterium tuberculosis (TB)
- Fungal agents
- Toxoplasma gondii
- Brain abscess
- Nocardia spp
- Encephalitis
- Meningitis
Connective tissue diseases
- Systemic lupus erythematosus
- Sjögren syndrome
Other
- Sarcoidosis

Background

Epidemiology

Incidence
- Endemic in Mexico, Central America, and South America
- Etiological agent in 10% of new onset seizures
Sex – M:F equal

Organism

Humans can be definitive host (adult worm in intestine) or dead-end intermediate host (cysticercosis)
Humans are incidental hosts by contact with contaminated water or undercooked pork
Human disease depends on site of infection
- Tapeworm in intestine
- Larval forms in tissues
Symptoms begin when cyst dies; depends on where the cysts are located
Dying cyst releases antigenic material, triggering the host inflammatory response

Clinical Presentation

Initial infection often asymptomatic
- Rapid onset dependent on number of cysts and body site affected
Parenchymal
- Most common form
- Enhancing lesions
- Often asymptomatic – found incidentally during imaging
- Seizures
Extraparenchymal
- Intraventricular or subarachnoid space disease
- Obstructive hydrocephalus
- Subarachnoid disease – stroke, vasculitis, meningitis/encephalitis
Ocular cysts
- Usually vitreous; can be subretinal
- Blurry or disturbed vision, swelling or retinal detachment

ARUP Lab Tests

Tests generally appear in the order most useful for common clinical situations. Click on number for test-specific information in the ARUP Laboratory Test Directory.

Cysticercosis Antibody, IgG by ELISA (CSF) (Temporary Referral as of 01/02/19) 0055285
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Recommended Use

Detect the presence of CSF IgG antibodies to T. solium if clinical suspicion of cysticercosis exists

Limitations

Diagnosis of central nervous system infections can be accomplished by demonstrating the presence of intrathecally-produced specific antibody

Interpretation of results may be complicated by low antibody levels found in CSF, passive transfer of antibody from blood, and contamination via bloody taps

Cysticercosis Antibody, IgG by ELISA (Temporary Referral as of 12/20/2018) 0055284
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Recommended Use

Detect presence of IgG antibodies to T. solium in serum if clinical suspicion of cysticercosis exists

Limitations

Patients with collagen vascular diseases, hepatic cirrhosis, schistosomiasis, and other parasitic infections can produce false-positive results

Medical Experts

Couturier, Marc Roger, PhD, D(ABMM), Medical Director, Microbial Immunology, Parasitology and Fecal Testing, and Infectious Disease Antigen Testing at ARUP Laboratories; Associate Professor of Clinical Pathology, University of Utah

References

General References

Brunetti E, White C. Cestode infestations: hydatid disease and cysticercosis. Infect Dis Clin North Am. 2012; 26(2): 421-35. PubMed

Del Brutto OH. Neurocysticercosis: a review. ScientificWorldJournal. 2012; 2012: 159821. PubMed

Kraft R. Cysticercosis: an emerging parasitic disease. Am Fam Physician. 2007; 76(1): 91-6. PubMed

Ramírez-Zamora A, Alarcón T. Management of neurocysticercosis. Neurol Res. 2010; 32(3): 229-37. PubMed

Sinha S, Sharma BS. Neurocysticercosis: a review of current status and management. J Clin Neurosci. 2009; 16(7): 867-76. PubMed

Sotelo J. Clinical manifestations, diagnosis, and treatment of neurocysticercosis. Curr Neurol Neurosci Rep. 2011; 11(6): 529-35. PubMed

Last Update: December 2018