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Flashcards in Trematodes and Cestodes Deck (19)
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1
Q

List the trematodes and cestodes:

A
  • 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.
2
Q

Life cycle of Dephyllobothrium latum (broad fish tapeworm)?

A

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

3
Q

Pathogenesis of Dephyllobothrium latum (broad fish tapeworm)?

A

Pernicious anemia (worm competes with host for B12)

Usually 1 worm; mild manifestations

4
Q

Epidemiology of Dephyllobothrium latum (broad fish tapeworm)?

A

Russia, Sweden, Minnesota, Wisconsin, Pacific salmon (sushi)

Raw fish, sushi are big

5
Q

Diagnosis / Treatment of Dephyllobothrium latum (broad fish tapeworm)?

A

Demonstrate eggs / proglottids in stool

Praziquantel (and B12)

6
Q

Life cycle of Taenia saginata?

A

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

7
Q

Pathogenesis of Taenia saginata?

A

Present singly; Concomitant immunity (one tapeworm prevents another, really) (once worm is in, Ab to other parasites as well)

Mostly asymptomatic

8
Q

Diagnosis / Treatment of Taenia saginata?

A

Gravid proglottids in feces (but can’t tell Taenia eggs from one another)

Praziquantel (90% cure rate)

9
Q

Life cycle of Taenia solium?

A
  • 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)

10
Q

Pathogenesis of Taenia solium?

A

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
11
Q

Diagnosis / Treatment of Taenia solium?

A

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
12
Q

Epidemiology of Taenia solium?

A

Mexico, C./S. America, Africa, East Asia

  • Orthodox Jewish community in New York City (illegal Hispanic housekeepers)
  • Migrant workers, often
13
Q

Brief overview:

Schistosoma mansoni

A
  • Veins around intestines
  • Africa, S. America, Carribean
  • Biomphalaria snails
14
Q

Brief overview:

Schistosoma haematobium

A
  • Veins (bladder)
  • Africa / Near East
  • Bulinus snails
15
Q

Brief overview:

Schistosoma japonicum

A
  • Mesenteric veins
  • China, Philippines
  • Oncomelania snails (freshwater)
16
Q

Life cycle of Schistosoma?

A
  • 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)
17
Q

Pathogenesis of Schistosoma?

A

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)

18
Q

Diagnosis / Treatment of Schistosoma?

A

Eggs in feces for mansoni/japonicum
Eggs in urine for haematobium

Praziquantel (2 doses in 1 day)

19
Q

What is Swimmers itch? (a bird schistosome)

A

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