Trematodes and Cestodes Flashcards
List the trematodes and cestodes:
- Diphyllobothrium latum (broad fish tapeworm)
- Taenia saginata (beef tapeworm)
- Taenia solium (pork tapeworm)
- Schistosoma mansoni (trematode)
- Schistosoma haematobium (trematode)
- Schistosoma japonicum (trematode)
- Swimmer’s itch.
Life cycle of Dephyllobothrium latum (broad fish tapeworm)?
30 years - 10-30 feet
Eggs water –> coracidium injested by Copepod (become procercoid stage) –> then eaten by minnow (encysts in muscles (Pleurocercoid)
From here, bigger things eat minnows, get up to trout/salmon
Poorly-cooked freshwater fish
Pathogenesis of Dephyllobothrium latum (broad fish tapeworm)?
Pernicious anemia (worm competes with host for B12)
Usually 1 worm; mild manifestations
Epidemiology of Dephyllobothrium latum (broad fish tapeworm)?
Russia, Sweden, Minnesota, Wisconsin, Pacific salmon (sushi)
Raw fish, sushi are big
Diagnosis / Treatment of Dephyllobothrium latum (broad fish tapeworm)?
Demonstrate eggs / proglottids in stool
Praziquantel (and B12)
Life cycle of Taenia saginata?
Small intestine in human –> proglottids pass in feces –> eggs in soil –> cattle graze
Oncosphere lodges in cow intestine –> blood/lymph to muscles (now called cysticercus)
Undercooked meant
Pathogenesis of Taenia saginata?
Present singly; Concomitant immunity (one tapeworm prevents another, really) (once worm is in, Ab to other parasites as well)
Mostly asymptomatic
Diagnosis / Treatment of Taenia saginata?
Gravid proglottids in feces (but can’t tell Taenia eggs from one another)
Praziquantel (90% cure rate)
Life cycle of Taenia solium?
- Contaminated food/drink from human feces
- Reverse peristalsis: eggs to stomach
Bonus! Oncosphere –> penetrates wall –> mesenteric veins –> cysticerci in brain, eye, muscle, lungs
Nodules (cysticercus)
Pathogenesis of Taenia solium?
Few problems caused by adults in the intestines
Cysticercosis: severity depends on number and location
- MAIN SITE is subcutaneous connective tissue
- Ocular cysticercosis (damage retina/iris –> blindness)
- Brain (neurocysticercosis)
- Sudden epilepsy
Diagnosis / Treatment of Taenia solium?
Find gravid proglottids in feces
Cysticercosis: soft tissue x-rays or CT to visualization - Albendazole, cysticercosis surgery - Steroids to minimize inflammation Praziquantel for intestinal worms Steroids to minimize inflammation
Epidemiology of Taenia solium?
Mexico, C./S. America, Africa, East Asia
- Orthodox Jewish community in New York City (illegal Hispanic housekeepers)
- Migrant workers, often
Brief overview:
Schistosoma mansoni
- Veins around intestines
- Africa, S. America, Carribean
- Biomphalaria snails
Brief overview:
Schistosoma haematobium
- Veins (bladder)
- Africa / Near East
- Bulinus snails
Brief overview:
Schistosoma japonicum
- Mesenteric veins
- China, Philippines
- Oncomelania snails (freshwater)
Life cycle of Schistosoma?
- Eggs excreted from human (eggs are diagnostic)
- Miracidia inside (free larvae that must find snail)
- Asexually amplifies in snail
- Free-swimming cercariae (infective in humans) - penetrate unbroken skin
- Mature/mate in the liver
- Final place depends on species (like the veins; produce eggs 20-30 years)
Pathogenesis of Schistosoma?
Eggs cause disease; Adult worms (antigenic mimicry)
- Papule at penetration site
- Acute phase (egg-laying): FEVER, discomfort, pain
- Chronic phase: Fibrosis of intestines (if eggs there) - thicken and lose fxn; Granuloma if in liver/spleen - block blood flow –> portal hypertension, hepatosplenomegaly
S. haematobium causes ulceration of bladder (bladder cancer)
Diagnosis / Treatment of Schistosoma?
Eggs in feces for mansoni/japonicum
Eggs in urine for haematobium
Praziquantel (2 doses in 1 day)
What is Swimmers itch? (a bird schistosome)
Cercariae enter human skin (we are unsuitable hosts); walled off and destroyed –> inflammation and rash
Antihistamine lotion; vigorous rubbing with towel reduces probability of penetration
