Platyhelminths : Cestodes

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Platyhelminths Cestodes

• Pseudophyllidea
• Diphyllobothrium latum (pernicious anemia)

• Cyclophyllidea
• Taenia solium (pork tapeworm)
• Taenia saginata (beef tapeworm)
• Echinococcus granulosus (cystic, CE)
• Echinococcus multilocularis (alveolar, AE)

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A rare and emerging disease
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Macroparasite example 2 Taenia solium Disease
Neurocysticercosis
Cestode. Unique zoonosis. Under-reported disease.
Diagnostic difficulties. Lack of epidemiological
data.
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Biology of Taenia solium

• Unique zoonosis Human only known definitive
  host, pig intermediate host
• Humans carry both adult worms in the intestine
  larval cysticercosis in the muscle other
  tissues
• Infection with adult worm in humans dangerous to
  host other contacts
• Under-reported disease

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Symptomatology and pathology 1

• Primarily due to pressure effects of a
  space-occupying cyst or lesion in an organ or
  tissue
• CNS involvement Neurocysticercosis (NCC)
  pathology relates to number, size, type
  (cellulose or racemose), condition site of
  cysticerci in the brain
• Active versus inactive NCC

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Symptomatology and Pathology 2

• Active NCC arachnoiditis (spinal fluid
  pleocytosis, increased CSF protein, positive CSF
  serologic test)
• Small number of patients obstructive
  hydrocephalus, cranial nerve involvement,
  intercranial hypertension, arterial thrombosis
  stroke
• Epilepsy, dementia, meningitis

Intraocular cysts visual impairment
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Location of parasites in 2188 cases of
cysticercosis

• CNS 82
• Eye 17
• Subcutaneous
• tissue 7
• Muscle 5
• Other organs 6
• Generalized 1

Flisser Craig, 2005
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Diagnosis 1

• Adult worms
• Stool analysis uterine branch structure or
  scolex morphology after treatment
• Molecular differentiation of adult worms
• Capture ELISA for coproantigen detection

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Diagnosis 2

• Cysticercosis
• Imaging methods (CT scan useful for brain
  calcified cysts MRI not but excellent for
  detecting active cysts in soft tissue)
• Serology (ELISA versus Immunoblot)

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Epidemiology cysticercosis

• Retrospective case finding
• fixed time period, annual incidence rate per
  100,000 population
• Active screening
• Mass radiological imaging surveys
• Immunodiagnostic surveys
• Autopsy surveys

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Cysticercosis in communities

• Endemic focus Rural Latin America
• Major risk factor current or past case of
  intestinal Taenia in the household
• Non-endemic community New York City
• Significant number of human cysticercosis cases
  in an Orthodox Jewish community

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Treatment cysticercosis

• Until recently symptomatic patients
  anticonvulsants, corticosteroids, surgery
• Chemotherapy
• CT useful for monitoring
• Active parenchymal brain cysts and subarachnoid
  (racemose) cysts albendazole
• Albendazole also effective against ocular
  cysticercosis
• Alternative drug praziquantel less effective

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Control Taenia solium

• Freezing and appropriate cooking of pork
• Identification and treatment of Taenia carriers
  (mass treatment ?)
• Improved health education, prevention of
  vegetables irrigated with contaminated water
• Confinement of pigs
• Porcine vaccine