Intestinal helminths Flashcards
What is the other name for trematodes?
Flukes
Which trematode is not hermaphroditic?
Schistosomiasis
What are the 5 trematodes?
Schisto
Clonorchis sinuses
F. hepatica/buski
P.westermani
H. heterophyes
Discuss the life cycles of trematodes
Eggs released in faeces -> miracidia -> primary host (snails) -> secondary host -> ingest/penetrate -> large GI -> excyst if miracidia
- bile duct (f. hepatica, c. sinensis)
- lung (p. westermani)
- mucosa (f. buski)
What is the ‘Chinese liver fluke’?
C. sinensis
Discuss the life cycle of c.sinensis
- Metacercariae ingested with raw fish -> larva hatch in small intestine -> larva migrate to bile duct
- Worm matures and adults live in bile duct
- Embryonated eggs pass in faeces -> eggs eaten by snail -> miracidium hatches in snail
- Cercaria leave snail and encyst on fish
- Metacercaria in fish muscle
What is the shape of c.sinesis called?
Coffee pot
Which trematode produces the largest parasitic eggs?
F. hepatica
Discuss the life cycle of p.westermani
- Metacercariae ingested with raw crab -> worms hatch in small intestine -> mature in lung
- Unembronayed eggs in lung passed in faeces
- Miracidia penetrate snail -> cercariae leave snail -> cercaeriae encyst in crab -> metacercariae
What is p.westermani also called?
‘Lung fluke’
What are tapeworms also called?
Platyhelminths
Which tapeworm does not require an animal intermediate host?
Hymenolepsis nana
What is the beef tapeworm?
Taenia saginata
What is the pork tapeworm?
Taenia solium
What is the fish tapeworm?
Diphyllobothrium latum
What is the rat tapeworm?
Hymenolepsis dimunata
What is the dog tapeworm?
Dipylidium caninum
How many suckers does the saginata scolex have?
4
How do you differentiate the proglottids of saginata vs solium?
Saginata >15 uterine branches
Solium <15 uterine branches
Discuss the life cycle of the fish tapeworm
- Pleurocercoid larvae ingested via raw fish
- Adults live in small intestine (2 groove scolex)
- Gravid proglottid passes to colon if faeces deposited into water the larvae hatch in water
- Copepod eats larva -> minnow eats copepod -> fish eats minnow
Discuss the life cycle of hymenolepsis nana
- Embryonated eggs in faeces -> ingested by insects -> cysticercoid develops and ingested when humans eat arthropods
- Oncosphere hatches and cysticercoid develops in intestinal villus
- Adult in ileum -> eggs released via genital atrium of gravid proglottids
- Autoinfection if eggs remain in intestine (hexacanth embryo penetrates intestinal villus to continue cycle)
Name the intestinal nematodes
Enterobius vermicularis
Trichuris trichiura
Ascaris lumbricoides
Ancylostoma/necator
Strongyloides stercoralis
Pinworm name?
Enterobius vermicularis
Whipworm name?
Trichuris trichina
Roundworm name?
Ascaris lumbricoides
Hookworm name?
Ancylostoma/necator
Threadworm name?
Strongyloides stercoralis
Which intestinal nematode is NOT a soil transmitted helminth?
Enterobius vermicularis
Which nematode has ‘tea tray’ eggs?
Trichuris
Which nematode has 3 lips at mouth?
Ascaris
Which nematode has mammelated eggs?
Ascaris (lumps and bumps)
Which nematodes can cause Loeffler syndrome?
Strongyloides
Ascaris
Hookworms
What is the treatment of strongyloides?
Ivermectin
Albendazole (adult worms only)
Which nematode can produce without a male?
Strongyloides
Discuss the clinical presentation of strongyloides
Diarrhea
Rash
Abdominal pain
Eosinophilia
Which nematode causes larva currens?
Strongyloides
What is sandworm and what rash does it cause?
Dog hookworm
Larva migrans (slow, chronic)
