cestodes

• cestodes are under subkingdom metazoa (phylum platyhelminthes), and are considered as primitive worms
• cestodes absorbs nutrients and eliminate waste product through tegument
• cestodes do not possess digestive nor nervous system
• commonly known as tapeworm or flatwom
• consist of three regions: head, neck, and body (proglottids)
• the head contains an organ of attachment (scolex)

  • gooks, sucker, sucking grooves
  • scolex has an extension (rostellum) where hooks are attached
• body is divided into multiple segments (proglottids)

  • series of proglottids: strobila
• cestosed are hermaphroditic (sel-fertilizing)

  • contains both male and female reproductive organs
  • capable of laying eggs (gravid segment)
• the neck is the region of growth, connecting the head to the body

  • grows by adding new proglottids to the neck
• cestode life cycle: egg > larva > adult
• intestinal cestodes

  • taenia saginata (beef worm)
  • taenia solium (pork tapeworm)
  • diphyllobothrium latum (broad fish tapeworm)
  • hymenolepis nana (dwarf tapeworms)
• taenia sagitana (beef tapeworm)

  • intermediate host: cattle
  • egg > blood vessel (intestine) > skeletal muscle > develop into cysricerci (larvae)
  • acquired through ingestion of improperly cooked or raw beef containing cysticercus
  • patients are asymptomatic
  • complain of diarrhea, abdominal pain, loss of appetite with weight loss and body malais
  • may reach to the anus causing pruritis ani
  • drug choice is praziquantel
• taenia solium (pork tapeworm)

  • acquired through ingestion of improperly cooked or raw pork containing custicercus cellulosae ; food or water contaminated with human feces
  • two infective stage: egg and larvae
  • autoinfection may occur
  • intermediae host: pigs
  • drug of choice is paraziquantel
  • alternative drug: albendazole, paromomycin, and quinacrine hydrochloride
• diseases in taenia solium:

  • taeniasis - produced by adult worm
  • cysticerocsis - result of larval encystation, common complain is muscle pain
• diphyllobothrium latum (broad fish tapeworm)

  • longest tapeworm (13 meters)
  • eggs consist of ciliated larvae (coracidia)
  • acquired through ingestion of improperly cooked or raw fish contaning plerocercoid
  • prerocercoid > intestinal mucosa = matures (adult worm) > self fertilizes > egg excreted with the stool
  • cause little damage in the small instestine
  • drug of choice: praziquantel
  • alternative drug: niclosamide
• diseases in diphyllobothriasis:

  • asymptomatic disease - most common
  • diphyllobothriasis - gastrointestinal involvement, deficiency of B12, megablostic anemia
• hymenolepis nana (dwarf worm)

  • does nat required pnligatory animan host
  • egg are direction infection
  • acquired through ingestion of fecally-contaminated food or water / touching mouth / contaminated soil
  • rodents - additional source of infection
  • egg transform into cysticercoid larvae after ingestion
  • pathway: passed out as fece / remains inside and re-infect host (autoinfection)
  • drug of choice is praziquantel
  • alternative drug is niclosamide
• extra-intestinal cestodes: echinococcus granulosus (dog / hydatid tapeworm)

  • zoonotic type of infection
  • most important definitive host: dogs
  • intermediate host: sheep
  • diagnostic stage is larval form that is encased in a cyst wall (hydatid cyst)
  • ingestion of egg from food and water contaminated by dog feces / contact with contaminated dog fece
  • transform into larve in intestine and migrate through bloodstream to different tissue of the body (liver and lungs)
  • if the cyst enlarges, necorsis of infected tissue occurs
  • treatment of choice: removal of cyst
  • drugs: mebendazole, albendazole, paziquantel