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CysticercosisAka: Neurocysticercosis, Pork Tapeworm, Taenia solium

Pathophysiology: Tapeworm lifecycle and pathogenesis
1. Pork Tapeworm infection (taenia solium)
2. Infection originates in pigs as Tapeworm larvae (cysts)
3. Key points related to cysticercosis pathogenesis
  1. Tapeworms cycle between human hosts and pigs
    1. Humans ingest Tapeworm cysts in undercooked pork
    2. Pigs ingest human feces with Tapeworm eggs
  2. Ingestion of cysts does not cause cysticercosis
    1. Cyst ingestion allows Tapeworm development
    2. Ingested eggs are required for cysticercosis
  3. Cysticercosis is a result of fecal-oral ingestion
    1. Cysticercosis is not due to eating undercooked pork
    2. Cysticercosis occurs from infected human feces
      1. Can infect vegetarians from unwashed fruit
4. Humans ingest Tapeworm larvae with undercooked pork
  1. Larvae attach to human gut and grow to adult Tapeworm
  2. Adult Tapeworm sheds egg bundles (proglottids)
  3. Proglottids passed into human stool
5. Pigs ingest food contaminated with infected human stool
  1. Pigs ingest Tapeworm eggs
  2. Eggs develop into Tapeworm larvae
  3. Larvae enter pig bloodstream
  4. Larvae invade pig tissues and develop into cysts
6. Humans ingest food contaminated with infected stool
  1. Source: Ingested Tapeworm eggs
    1. Infected food handlers who do not wash hands
    2. Fruit or vegetables with infected fertilizer
  2. Source: Autoinoculation
    1. Tapeworm eggs retrograde travel gut to stomache
  3. Cysticercosis occurs in similar fashion as with pigs
    1. Ingested eggs develop into Tapeworm larvae
    2. Larvae travel via blood to tissue where they embed
    3. Larvae form cysts in brain, eyes, spine, and muscle
Signs
1. General
  1. Cysts may be single or multiple (even hundreds)
  2. Cysts are initially asymptomatic for years
    1. Larvae in cysts are walled off from host response
  3. Cysts degenerate and cause severe inflammation
    1. Release larvae and cause host antigenic response
    2. Inflammation and edema result in symptoms
2. Distribution
  1. Brain Parenchymal Neurocysticercosis (90% of cases)
    1. Seizures (most common)
    2. Headaches
    3. Parkinsonism
    4. Encephalopathy (if numerous brain cysts)
    5. Obstructive Hydrocephalus (if ventricles involved)
    6. Meningitis (mass effect with large cysts)
    7. Cranial Nerve palsy (mass effect with large cysts)
    8. Radiculopathy (if spinal cord involved - uncommon)
  2. Skeletal muscle lesions
  3. Subcutaneous lesions
  4. Eye lesions (1-3% of cases)
    1. Ocular lesions (e.g. vitreous lesions)
    2. Extraocular muscle lesions
Imaging: CT Brain
1. Diagnostic findings suggestive of neurocysticercosis
  1. Single <2 cm lesion
  2. No midline shift
  3. Larval sucking parts (scolex) may be visible
2. Differntiating cyst stage
  1. Viable non-degenerating cyst: Not contrast enhanced
  2. Degenerating cyst (symptomatic): Contrast-enhancing
  3. Old cysts: Calcified
3. Differential diagnosis
  1. Tuberculosis
  2. Parasitic Brain Lesions (e.g. Toxoplasmosis)
  3. Brain Tumor
  4. Brain abscess
4. Other imaging modalities
  1. Consider MRI brain if CT non-diagnostic
  2. Ultrasound or CT are approriate to image eye
Labs
1. Cysticercal Ab: Serum Enzyme-linked immunoblot assay
  1. Test Sensitivity: >65%
  2. Test Specificity: >67%
  3. Serum more accurate than CSF titers
2. Biopsy of infected tissue
Diagnostics
1. Dilated eye exam if ocular involvement suspected
Management
1. Precautions: Do not start treatment without consult
  1. Treatment is individualized by multiple factors
  2. Antiparasitic agents are not uniformly indicated
    1. Overwhelming host response could be devastating
    2. Use may risk morbidity or mortality in some cases
  3. Consult infectious disease in nearly all cases
  4. Consult neurology and neurosurgery in CNS cases
2. Skeletal muscle lesions
  1. No treatment unless painful
  2. Consider surgical excision
3. Eye: Intraocular lesions
  1. Consult ophthalmology
  2. Surgical excision for intraocular lesions
4. Eye: Extraocular muscle lesions
  1. Consult ophthalmology
  2. Surgical excision for intraocular lesions or
    1. Consider Albendazole with Corticosteroid
5. Brain: Subarachnoid and intraventricular lesions
  1. Ventricular shunt placed if Hydrocephalus
  2. Surgical excision for most lesions or
    1. Consider Albendazole with Corticosteroid
6. Brain: Parenchymal Neurocysticercosis
  1. Albendazole with Dexamethasone (preferred)
    1. Do not use in massive infection
    2. Not needed in calcified lesions
  2. Anticonvulsants if concurrent Seizures
    1. Phenytoin
    2. Carbamazepine
References
1. Garcia (2000) Infect Dis Clin North Am 14:97
2. Kraft (2007) Am Fam Physician 76:91

Cysticercosis (C0010678)
Definition (MSH)	Infection with CYSTICERCUS, a larval form of the various tapeworms of the genus Taenia (usually T. solium in man). In humans they penetrate the intestinal wall and invade subcutaneous tissue, brain, eye, muscle, heart, liver, lung, and peritoneum. Brain involvement results in NEUROCYSTICERCOSIS. (From Dorland, 28th ed)
Concepts	Disease or Syndrome (T047)
ICD9	123.1, 123.1
MSH	D003551
English	Cysticerciasis, Cysticercoses, Cysticercosis, Infection by tapeworm larvae, Larval taeniasis, Larval tapeworm infection, Larval teniasis
Spanish	cisticercosis, infeccion por larvas de tenia
Parent Concepts	Other cestode infection (C0153296), Teniasis (C0039254), Parasitic infection (C0747256), Cestode Infections (C0007894), Cysticercosis (C0010678)
Sources	COSTAR, DXP, ICD9CM, LCH, MSH, MTHICD9, NCI, NDFRT, SCTSPA, SNOMEDCT Derived from the NIH UMLS (Unified Medical Language System)

Neurocysticercosis (C0338437)
Definition (MSH)	Infection of the brain, spinal cord, or perimeningeal structures with the larval forms of the genus TAENIA (primarily T. solium in humans). Lesions formed by the organism are referred to as cysticerci. The infection may be subacute or chronic, and the severity of symptoms depends on the severity of the host immune response and the location and number of lesions. SEIZURES represent the most common clinical manifestation although focal neurologic deficits may occur. (From Joynt, Clinical Neurology, 1998, Ch27, pp46-50)
Concepts	Disease or Syndrome (T047)
MSH	D020019
English	Brain Cysticercosis, Central Nervous System Cysticercosis, Cerebral cysticercosis, CNS CYSTICERCOSIS, CYSTICERCOSIS CNS, Cysticercosis of central nervous system, Neurocysticercoses, Neurocysticercosis
Spanish	cisticercosis cerebral, cisticercosis del sistema nerviosa central, neurocisticercosis
Parent Concepts	Cysticercosis (C0010678), Central Nervous System Helminthiasis (C0752185), Neurocysticercosis (C0338437), Intracranial non-pyogenic abscess (C0393499), Central Nervous System Parasitic Infections (C0752181), Infectious disease of brain (C1264609), Cerebral Abscess (C1510428)
Sources	MSH, NDFRT, QMR, SCTSPA, SNOMEDCT Derived from the NIH UMLS (Unified Medical Language System)

Tenia solium infection (C0473878)
Concepts	Disease or Syndrome (T047)
ICD9	123.0, 123.0
English	Armed tapeworm infection, Infection by Taenia solium, Intestinal taenia solium infection, Pork tapeworm, Pork tapeworm infection, Taenia solium infection, TAENIA SOLIUM INTESTINE, Tenia solium infection
Spanish	infeccion por la tenia de los cerdos, infeccion por Taenia solium, infeccion por tenia solium
Parent Concepts	Other cestode infection (C0153296), Teniasis (C0039254), Intestinal tract infectious disease NOS (C0178238), Tenia solium infection (C0473878), Ambiguous concept (C1274012)
Sources	ICD9CM, MTH, MTHICD9, SCTSPA, SNOMEDCT Derived from the NIH UMLS (Unified Medical Language System)

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CysticercosisAka: Neurocysticercosis, Pork Tapeworm, Taenia solium

Cysticercosis (C0010678)

Neurocysticercosis (C0338437)

Tenia solium infection (C0473878)

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