Helminthology Flashcards
Mar 4th 2013
Trematodes
Hermaphroditic flukes
Adult in lung, intestine or liver
Transmitted through snail, fish, vegetable or crustacean
Trematode
Paragonimus westermanii
Eggs hatch & penetrate snail *in water
Humans ingest inadequet cooked/ pickled crustacean w/ metacercariea
Excyst in duodenum
Adults in cystic cavities in lugs where lay eggs & excreted in sputum.
Eggs are swallowed & passed in stool.
Fasciola Hepatica
Eggs in cattle feces
Embryonate in water
Penetrate snail
Free swimming cercariae on water plants
Ingested by human, sheep or cattle
Excyst in duodenum
Adults in hepatic biliary ducts
Fasciolopsis buski
Eggs in pig pass in feces
Embryonated eggs in water
Hatch to penetrate snail
Free swimming cercariae
Metacercariae on water plants get ingested by humans/pigs
Excyst in duodenum
Adults in small intestine
Clonorchis sinensis
Pass in feces
Eggs ingested by snail
Free swimming cercariae encyst in skin or flesh of fresh water fish
Metacercariae in flesh of fish ingested by human
Excyst in duodenum
Adults in biliary duct
S masoni, S japonicum & S. hematobium - schistosomias
in feces/urine
Eggs hatch in water
Penetrate snail tissue
Sporocysts in snail
Cercariea released by snail into water
Penetrate human skin
Enter circulation as schistosomulae
Migrate to portal blood in liver & mature into adults
Paired adult worms migrate to bowel/rectum to lay eggs AND
venous plexus of bladder
Diphylobothrium Latum
Tapeworm
Eggs from feces
Hatch from eggs & ingested by crustaceans
Larve in body cavity of crustaceans
Infected crustacean ingested by small water fish, further develop into larva
Predator fish eats infected samll fish
Human ingest raw or undercooked infected fish
Scolex & adults in small intestine. Release immature eggs
Taeniasis
T. saginata (beef)
T solium (pork)
Eggs in feces
Cattle & pigs become infected by ingesting vegetation contaminated with eggs
Hatch & penetrate animal intestinal wall & circulate to m.
Develop in m. to cysticerci
Human infected by ingestion raw or undercooked infected meat
Scolex attach to intestine
Adults in small intestine
Echinococcus granulosus & multilocularis
Adult in small intestine, release egg in feces
Egg hatches to penetrate intestinal wall
Hydatid cyst in liver, lungs
Protoscolex from cyst turn to scolex which attach to intestine
Dogs & cattle from organs/feces
Human affects: brain, heart, lungs, liver, spleen, intestine, bone
Nemathelminthes- intestinal nematodes
Ascaris Lumbricoides
roundworm
From feces, plants become infected
Human ingest plants
Affects esophagus, lungs, intestines
Strongyloides stercoralis
threadworm
Larvae found in stool,
Penetrate intact skin to initiate infection
Enter ciruclation, to lungs to alveolar spaces. Carried to trachea & pharynx.
Reach small intestin when adults.
Autoinfection in large intestine, penetrate mucosa etc.
Enterobius Vermicularis
Pinworm
Eggs in perianal folds
Ingested by human
Larvae hatch in small intestine
Adults in cecum
Hookworm
Eggs in feces
Larva hatch and penetrate skin
Adults in small intestine
Trichinella Spiralis
No eggs, Carnivorism transmission
Ingestion of undercooked meat like prok
Larva in small intestine
Adults in small intestine
Larva deposited in mucosa & into circulation
Pigs ingest meat scarps of animals like rodents who display carnivorism and become infected!
Tissue nematodes Filaria
Wuchereria bancrofti
Mosquito takes a blood meal
Adults in lymphatics
Adults produce sheathed microfilariae that migrate into lymph & blood channels.
