Trematodes and Cestodes Flashcards
What is the general term to refer to both trematodes and cestodes?
Flat worms
What is a simple distinction between trematodes and cestodes?
Tremtodes - non-segmented
Cestodes - segmented
What are commonalities of all trematodes?
Non-segmented flat worms
Molluscan intermediate host and vertebrate adult host
Digenetic (asexual and sexual phase)
Hermaphrodites (except shistosoma)
What is the method of transmission of Schistosomiasis?
Water-borne
Commonly seen in snails with lily pads
What is the life cycle of Schistosomiasis?
Miricidia: photosensors swim upward toward light to snails (intermediate host)
Cercaria: released by snails into fresh water and can penetrate skin
After penetration of skin, cercariae shed glycocalyx and become schistosomulum and migrate in blood vessels
Mature into adults and male and female worms mate for life and produce eggs
Eggs cause immune response
What is an almost immediate sign of Schistosomiasis?
Hypersensitivity rash at site of cercarial penetration
Penetrate epidermis within 5 minutes, dermis within 20
What is the presentation of acute schistosomiasis?
Katayama fever
Fever, headache, cough, abdominal pain, eosinophilia, prostration, death
What is the presentation of chronic schistosomiasis?
Eggs become trapped in tissue, granulomas develop and fibrosis
Commonly affects liver or bladder, can go to lungs or CNS
- Liver: bloody diarrhea, intestinal polyps, periportal fibrosis
- Urinary: hematuria, polyps, bladder calcifications and strictures, bladder cancer
- CNS: neuro-schistosomiasis, transverse myelitis or brain lesions
Which species cause liver schistosomiasis?
S. mansoni
S. japonicum
Which species cause urinary schistosomiasis?
S. haematobium
How is schistosomiasis diagnosed?
Microscopically
Serologic tests
How does Schistosoma mansoni appear microscopically?
Lateral spine
How does Schistosoma haematobium appear microscopically?
Terminal spine
How does Schistosoma japonicum appear microscopically?
Small lateral spine with round egg
What is the treatment for schistosomiasis?
Praziquantel
What are species are in the category of liver fluke (also trematodes)?
Clonorchis sinensis
Opisthorchis
What is the mode of transmission of liver flukes?
Undercooked fish (cercariae are in flesh of fish)
What is the presentation of infection with liver fluke?
Inflammation of biliary tree since adults reside there
Cause massive RUQ abdominal pain
Cholangiocarcinoma
What are commonalities of all cestodes?
Flatworms but without GI tract (trematodes have GI tract)
Segmented
Segments contain male and female organs - hermaphrodites
Humans can harbor tapeworm itself or larval hydatid cyst
What are the major species of cestodes?
Diphyllobothrium latum - fish tapeworm
Taenia solium - pork tapeworm
(Taenia saginata - beef tapeworm)
Echinococcus granulosum
What is the mode of transmission of diphyllobothrium latum?
Undercooked fish
What makes the eggs of diphyllobothrium latum unique?
Has operculum that pops open when egg encysts
What are symptoms of diphyllobothrium latum infection?
Non-specific abdominal discomfort
Can develop megaloblastic anemia (tapeworm competes for B12 in intestine)
How is diphyllobothrium latum infection diagnosed?
Proglottids (tapeworm segments) or eggs in stool
What is the treatment for diphyllobothrium infection?
Praziquantel
How can you differentiate between different raw fish infections?
Liver flukes will have lots of symptoms
Diphyllobothrium will be relatively asymptomatic
What is the mode of transmission of Taenia solium and saginata?
Ingestion of raw pork or beef (can ingest either the worms or the cysticerci [egg form])
What are symptoms of Taenia infection when the worm is ingested?
Mild, non-specific
Intestinal infection
What are symptoms of Taenia infection when the cysticerci are ingested?
Cysticercosis
Predilection to infect nervous system, causing seizures, hydrocephalus, brain damage, adult epilepsy
What is the treatment for Taenia infection?
Praziquantel
Albendazole and surgery too for neurocysticercosis
What is the mode of transmission of Echinococcus granulosum?
Ingestion of eggs from dog feces
What are symptoms of Echinococcus granulosum infection?
Larvae develop into large hydatid cysts, usually in the liver
Rupture can be serious and cause anaphylaxis or biliary obstruction
How is the diagnosis of Echinococcus granulosum infection made?
CT scan, ultrasound, aspirate
What is the treatment for Echinococcus granulosum infection?
Inactivate cysts with hypertonic saline or ethanol and surgically remove
Albendazole/mebendazole
