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Disease Categories > Infectious Disease > Parasites

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Cysticercosis

Cysticercosis is a parasitic infection caused by the pork tapeworm, Taenia solium.

Epidemiology

Incidence
- Endemic in Mexico, Central and South America
- Etiological agent in 10% of new onset seizures

Organism

Humans are the only definitive host
The T. solium life cycle begins and ends in pigs
Humans are incidental hosts by contact with contaminated water or undercooked pork
Form depends on site of infection
- Tapeworm in intestine
- Larval forms in tissues

Clinical Presentation

Initial infection often asymptomatic
- Can have rapid onset depending on number of cysts and body site affected
Symptoms begin when cyst dies and depend on where the cysts are located
Dying cyst releases antigenic material, triggering the host inflammatory response
- Neurocysticercosis (cysts in the brain) is associated with seizures, meningoencephalitis, obstructive hydrocephalus
- Stroke patients initially present with elevated intracranial pressure (ICP), seizures, headache, nausea or mental status changes
Ocular cysts
- Usually vitreous, can be subretinal
- Blurry or disturbed vision, swelling or retinal detachment

Diagnosis

Diagnosis may be difficult, requires high index of suspicion in nonendemic areas
Clinician should use consensus criteria (see table below)
Diagnosis is made by MRI or CT brain scans most often, but serologic screening by ELISA and confirmation by Western Blot show increased sensitivity in the diagnosis of cysticercosis

Proposed Diagnostic Criteria for Human Cysticercosis

Absolute criteria
1. Demonstration of cysticerci by histologic or microscopic examination of biopsy materials
2. Visualization of the parasite in the eye by funduscopy
3. Neuroradiologic demonstration of cystic lesions containing a characteristic scolex
Major criteria
1. Neuroradiologic lesions suggestive of neurocysticercosis
2. Demonstration of antibodies to cysticerci in serum by enzyme-linked immunoelectrotransfer blot
3. Resolution of intracranial cystic lesions spontaneously or after therapy with albendazole or praziquantel alone
Minor criteria
1. Lesions compatible with neurocysticercosis detected by neuroimaging studies
2. Clinical manifestations suggestive of neurocysticercosis
3. Demonstration of antibodies to cysticerci or cysticercal antigen in CSF by ELISA
4. Evidence of cysticercosis outside the CNS (e.g., cigar-shaped soft tissue calcifications)
Epidemiologic criteria
1. Residence in a cysticercosis-endemic area
2. Frequent travel to a cysticercosis-endemic area
3. Household contact with an individual infected with Taenia solium

Key for Diagnostic Interpretation

Confirmation:

1 absolute criteria
2 major, 1 minor, and 1 epidemiologic criteria

Probable:

1 major and 2 minor
1 major, 1 minor, and 1 epidemiologic
3 minor and 1 epidemiologic

(Adapted with permission from White and Weller, 2005, 1274)

Treatment

Treatment is usually necessary
- CNS disease may require treatment for hydrocephalus

Indications for Ordering

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

Test Name and Number	Recommended Use	Limitations	Follow Up
Cysticercosis Antibody, IgG by ELISA 0055284 Method: Enzyme-Linked Immunosorbent Assay	Detect presence of IgG antibodies to T. solium in serum when a clinical suspicion of cysticercosis exists		CT or MRI suggested for neurologic presentations of the disease
Cysticercosis Antibody, IgG by Western Blot 0055283 Method: Western Blot	Confirm IgG antibodies to T. solium in serum or CSF Confirm positive results from ELISA testing	Consideration must be given to possible contamination by blood or transfer of serum antibodies across the blood-brain barrier	CT or MRI suggested for neurologic presentations of the disease
Cysticercosis Antibody, IgG by ELISA (CSF) 0055285 Method: Enzyme-Linked Immunosorbent Assay	Detect the presence of CSF IgG antibodies to T. solium, if a clinical suspicion of cysticercosis exists	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	CT or MRI suggested for neurologic presentations of the disease
Cysticercosis Antibody, IgG by Western Blot (CSF) 0055282 Method: Western Blot	Confirm IgG antibodies to T. solium in CSF Confirm positive results from ELISA testing	Interpretation of results may be complicated by low antibody levels found in CSF, passive transfer of antibody from blood and contamination via bloody taps	CT or MRI suggested for neurologic presentations of the disease

Additional Information

Due to the cross-reactivity that exists between cysticercosis and echinococcus antibodies, approximately 23%, a positive result by ELISA should be confirmed by Western blot.