Trematodes Flashcards
What is the morphology of trematodes (flukes)?
Flat worms with two suckers
What is the reproductive modality of trematodes (flukes)?
Hermaphrodites (except schistosomes)
What intermediate host is shared by all trematodes (flukes)?
Snails
Trematodes all have what three life stages
Miracidia - leaves egg, enters snail, Cercaria - leaves snail infects humans, Eggs - all have operculum except schistosomes
What are the four categories of trematodes based on where they live?
Intestinal, Hepatic, Pulmonary, and Blood (Schistosomes) Trematodes
What type of trematode is fasciolopsis buski?
An intestinal trematode (lives in duodenum or jejunum)
Where do fasciolopsis buski eggs encyst?
Aquatic vegetation (bamboo shoots, water chestnuts)
Symptoms of fasciolopsis buski infection
Abdominal pain, diarrhea
What type of trematode is fasciola hepatica and where does it live?
A hepatic treamtode, lives in bile ducts and gall bladder
How do fasciola hepatic get their eggs into the feces?
Through the common bile duct to the intestine
Symptoms of fasciola hepatic infection
Eosinophilia, abdominal pain, fever, hepatomegaly, biliary colic, jaundice. Later, macrocytic anemia, inflammation of gall bladder, gallstones
How do humans usually acquire fasciola hepatic infection?
Ingestion of fresh watercress (but who can live without fresh watercress?)
What type of trematode is clonorchis sinensis and where does it live?
Hepatic trematode (also called Chinese liver fluke), lives in bile passages
How do humans acquire clonorchis sinensis infection?
Eating infected fresh water fish
Symptoms of clonorchis sinensis infection
Liver dysfunction and gall bladder dysfunction
What two factors have made clonorchis sinensis infection very difficult to control?
Fertilzation of commercial fishponds with human feces (ew) and the fact that human infections persist for 50 years
What type of trematode is paragonimus westermani and where does it live?
Pulmonary trematode, lives in fibrous capsules in the lungs
How do paragonimus westermani eggs get into the feces?
Coughed up and swallowed
Where do paragonimus westermani cercariae encyst?
Fresh water crabs or crayfish soft tissues
How do ingested paragonimus westermani cysts get to the lungs?
Migrate through intestinal wall to peritoneal cavity and then through diaphragm to lung
Symptoms of paragonimus westermani infection
Ranges from 1) occasional cough to dyspnea, 2) fever, anorexia and pulmonary abcess, 3) pneumonia. Also convulsions and seizures in 1 pct of cases
What can be seen on a chest x-ray in the case of paragonimus westermani infection?
Infiltrates and cysts
Four ways schistosomes are different from other trematodes
1) Cercariae initiate infection by skin penetration, 2) Are males and females (not hermaphroditic), 3) Cylindrical, 4) Eggs have spines rather than operculum
What type of trematode is schistosoma japonicum and where does it live?
Blood trematode (schistosome), lives in mesenteric vein of small intestine
