Taenia solium

• Taenia solium

  Pork tapeworm

  
• Diagnostic stage

  • Egg
  • Cysticercus
• Infective stage

  • Cysticercus cellulosae
  • Egg (can cause cysticercosis in humans)
• Habitat

  Upper small intestine
• Autoinfection: YES
• Neurocysticercosis

  Humans act as intermediate hosts in this case
• Neurocysticercosis

  Autoinfection can occur through fecal-oral route (contaminated food and drinks)
• Poor hygienic practices
• Adult Taenia solium

  • Derives nourishment from the hosts
  • Shorter than T. saginata
  • 8,000 to 10,000 proglottids
• Scolex

  • 4 suckers
  • Rostellum armed with 25 – 30 hooklets in two rows
  • Smaller and more spherical than T. saginata
• Mature proglottid

  • Lateral genital pores which receives the semen and transferred to the vagina
  • No vaginal sphincter
• Cyclophillideans are apolytic, in contrast to pseudophyllideans which are anapolytic
• Taenia solium mature proglottid

  • Contains 3 lobes of ovaries (2 lateral ovaries and a central smaller ovary)
  • In contrast to T. saginata which only contains 2 lateral ovaries

  
• Gravid Proglottid

  • Has 7 – 13 uterine lateral branches
  • Undergo apolysis in chains – releasing 30,000 – 50,000 ova
  • T. saginata has 15 – 20 uterine lateral branches
• Ova

  • 31 – 43 um
  • Spherical, yellow to brown in color with thick radially striated embryonic shell
  • Oncosphere with 3 pairs of hooklets: Hexacanth
  • Ova not distinguishable from that of T. saginata

  
• Life cycle of Taenia solium

  1. Humans eats undercooked meat infected with cysticerci

  2. Larva establishes itself in the small intestine and matures into adult

  3. Gravid proglottids release eggs passed to the fecal material

  4. Eggs ingested by intermediate host (pigs) become oncospheres which encyst (cysticercus cellulosae)

  5. Humans ingest embryonated egg, infected with oncosphere which penetrates walls of small intestine and migrates to encyst (cysticercosis)

  6. Humans ingest undercooked or raw pig meat infected with cysticerci, cysticerci matures into adult hermaphroditic Taenia solium tapeworm

  
• Intestinal Infection

  • Proglottids are NOT active (unlike T. saginata)
  • T. solium proglottids DO NOT cause obstruction of the bile duct, pancreatic duct, and appendix
• Cysticercosis

  • Multiple and often develop in different organs, most commonly in striated muscle and brain
  • May be present in subcutaneous tissue, eyes, heart, lung, peritoneum
• Neurocysticercosis (NCC)

  • One of the most serious manifestation
  • Scolex may be found
  • A. Parenchymal: Neurologic deficit seizure
  • B. Extra-parenchymal: Sub-arachnoid form (racemous cysticercosis - POOR PROGNOSIS), Intraventricular form, Spinal form (rare)
• Death of larva


  • Inflammation → calcification
  • Brain: Seizure, visual and motor deficits, headache
  • CSF: CSF eosinophilia (non-specific)
  • Eyes: Retinal or subretinal location, May float in the vitreous or aqueous humor, Chorioretinitis and vasculitis → affect vision
• Diagnosis of Taeniasis

  • Demonstration of gravid proglottids and eggs in the stool
  • Demonstration of scolex = effective treatment
• Diagnosis of Cysticercosus

  • Suspicion if living in endemic area, presenting as seizure
  • CSF fluid analysis – High protein, decreased glucose, increased mononuclear cells
  • MRI and CT scans before and after treatment
• CT scan pattern for neurocysticercosis

  • Round low-density area without surrounding enhancement after administration of contrast dye (viable Larva with no inflammation)
  • Ring-like enhancement after injection of contrast dye (Dead larva)
  • Small calcified area within cystic space (Dead scolex)
• Ophthalmic cysticercosis

  • Visualization of cysticerci using opthalmoscope
  • Visualization of mass in the eye is suggestive of ophthalmic cysticercosis, but not specific
• Treatment

  • Praziquantel
  • Recovery of Scolex: demonstration of the scolex is tantamount to cure because it means that the treatment is effective. Without the scolex, the parasite can no longer produce new proglottids in the the neck
  • Negative stool examination three months after treatment
• Treatment for cysticercosis

  • Praziquantel or Albendazole
  • Steroids
  • Surgery
• Treatment for opthalmic cystivercosis

  • Surgery first followed by praziquantel or albendazole