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ID Week 5 > ICL 3.1: Worms & Cestodes > Flashcards

ICL 3.1: Worms & Cestodes Flashcards

1
Q

which groups are at risk for parasite infection?

A
  1. minorities
  2. immigrants
  3. poor
  4. disadvantaged communities
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2
Q

what are the parasitic infections we are most worried about?

A
  1. chagas disease
  2. neurocysticerosis
  3. toxocariasis
  4. toxoplasmosis
  5. trichomoniasis
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3
Q

what are the two groups of helminths?

A
  1. platyhelminths = flatworms –> cestodes (tapeworms) and trematodes (flukes)
  2. nemathelminthes = roundworms –> nematodes
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4
Q

how are cestodes transmitted?

A

cestodes = tapeworms

ALL cestodes are transmitted by ingestion

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5
Q

what are the characteristics of the cestode body?

A

cestode = tapeworm

may be METERS long

scolex has hooks, rostellum, and suckers

neck region = proglottids form

strobila = string of proglottidesthat are immature near neck and mature are you get farther away

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6
Q

where are adult cestodes found in the body?

A

adults are found in the intestine

but virtually no clinical effect!!

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7
Q

what form of a cestode causes disease?

A

adults are found in the intestine with virtually no clinical effect

it’s the larvae that hatch from eggs after they’re eaten by intermediate hosts that are the problem

the larvae penetrate through intestinal wall into tissues!

the most damaging disease is caused by larvae

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8
Q

what is the diagnostic feature of cestode infection?

A

eggs or proglottids in feces

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9
Q

how are cestodes transmitted?

A

by ingestion!!!!

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10
Q

which cestodes are ingested and cause intestinal infection?

A
  1. T. solium
  2. T. saginata
  3. Dipiyllobothrium latum
  4. Diplydium caninum
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11
Q

what is the common name for diphyllobothriasis?

A

fish tapeworm

they’re a cestode = tapeworm

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12
Q

what is the largest human tapeworm?

A

diphyllobothrium latum = fish tapeworm

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13
Q

what are the definitive hosts of diphyllobothrium latum?

A

diphyllobothrium latum = fish tapeworm

humans, bears, minks & other animals

definitive host = an organism which supports the adult or sexually reproductive form of a parasite

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14
Q

what are the intermediate hosts of diphyllobothrium latum?

A

2 intermediate hosts: larval stages in water, picked up by water flea (crustacean), then by fish (source of human infection)

we eat the infected fish and that’s how we get sick

intermediate host = an organism that supports the immature or nonreproductive forms of a parasite

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15
Q

what’s the transmission cycle of diphyllobothrium latum?

A
  1. unembryonated eggs are passed in feces
  2. eggs embryonate in water
  3. coracidia hatch from eggs and are ingested by crustaceans
  4. procercoid larvae in body cavity of crustaceans
  5. infected crustaceans are ingested by small freshwater fish
  6. predator fish eats infected small fish
  7. humans eat raw/undercooked infected fish
  8. adults end up in the small intestine
  9. proglottids release immature eggs

cycle starts over

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16
Q

what are the symptoms of diphyllobothrium latum?

A

virtually no clinical effect

epigastric pain, nausea, vomiting

occasional intestinal obstruction, diarrhea, and abdominal pain

very occasionally it can cause low levels of B12 = megaloblastic anemia

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17
Q

how do you diagnose diphyllobothrium latum?

A

operculated eggs with knob on the bottom of the shell or proglottids in feces

egg looks like a white oval with white speckles all inside it

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18
Q

how do you treat diphyllobothrium latum?

A

Niclosamide and Praziquantel

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19
Q

what are the definitive hosts of dipylidium caninum?

A

humans!!

pet-owners (cats and dogs)

children

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20
Q

what are the intermediate hosts of dipylidium caninum?

A

fleas

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21
Q

how do humans get dipylidium caninum?

A

humans get infected by ingesting fleas infected with cysticercoid

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22
Q

what is the life cycle of dipylidium caninum?

A
  1. proglottids are passed intact in the feces or emerge from perianal region of either animal/human hosts
  2. egg packets containing embryonated eggs are ingested by larval stage of flee
  3. oncospheres hatch from the eggs and penetrate the intestinal wall of the larvae – cysticercoid larvae develop in the body cavity
  4. adult flea harbours the infective cysticercoid
  5. host is infected by ingesting fleas containing cysticercoids

OR

animals can transmit the infected fleas to humans

  1. humans, normally children, acquire the infection by ingesting the infected flea
  2. adult in the small intestine –> the scolex attaches in intestine
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23
Q

what are the symptoms of dipylidium caninum?

A

virtually no clinical effect

can see abdominal discomfort, anal pruritus, and diarrhea

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24
Q

how do you diagnose dipylidium caninum?

A

eggs (colorless egg packets) or proglottids in feces

the eggs look like an oval egg with smaller circles inside the whole egg – the circles have a thick outer lining

25
Q

how do you treat dipylidium caninum?

A

praziquantel

26
Q

what is the common name for taenia saginata?

A

beef tapeworm

27
Q

what is the common name for taenia solium?

A

pork tapeworm

28
Q

what is the definitive host of taenia saginata?

A

human ONLY

adult tapeworm is in the intestine

29
Q

what is the intermediate host of taenia saginata?

A

ox, cattle

larval form is in the muscle

30
Q

how do people get infected with taenia saginata?

A

Humans do not get beef tapeworm from ingesting eggs, only by ingesting the larval form (in meat)

31
Q

what is the life cycle of taenia saginata?

A
  1. eggs or gravid proglottids in human feces and passed into environment
  2. cattle become infected by ingesting vegetation contaminated by eggs or gravid progiottids
  3. oncospheres hatch, penetrate intestinal wall, and circulate to musculature of cow

oncospheres develop into cysticerci in muscle

  1. humans infected by ingesting raw or undercooked infected meat
  2. scolex attaches to intestine
  3. adults in small intestine
32
Q

what is the definitive host of taenia solium?

A

human only!!!

adult tapeworm in intestine

aka pork tapework

33
Q

how do humans get taenia solium?

A

by eating pork containing cysticerci!

34
Q

what is the intermediate host of taenia solium?

A

pig or human!

cysticerci in muscle + organs= cysticercosis –> develops after eating eggs from human feces

35
Q

what is the life cycle of taenia solium that causes intestinal infection?

A
  1. eggs or gravid proglottids in human feces and passed into environment
  2. cattle become infected by ingesting vegetation contaminated by eggs or gravid progiottids
  3. oncospheres hatch, penetrate intestinal wall, and circulate to musculature of pig

oncospheres develop into cysticerci in muscle

  1. humans infected by ingesting raw or undercooked infected meat
  2. scolex attaches to intestine
  3. adults in small intestine
36
Q

what are the clinical symptoms of taenia saginata and taenia solium?

A

virtually no clinical effect

sometimes abdominal discomfort –> the main symptom is often the passage of proglottids trough the intestinal tract

T. solium taeniasis is less frequently symptomatic than T. saginata taeniasis

37
Q

what is the most important feature of taenia solium?

A

the risk of development of cysticercosis

38
Q

how do you diagnose taeniasis?

A
  1. eggs in the feces

the egg just looks like a plain oval that has a thick outer lining

  1. gravid proglottids
  2. scolex = rarely found
39
Q

how do you treat taeniasis?

A

praziquantel

40
Q

how do you prevent taeniasis?

A

cook you meat well

freezing meat at -20°C for at least 12 hours

sanitation = controlled disposal of human feces = keep out of water and vegetation!!

cattle or pigs must ingest grass contaminated with human feces to get infected!!

41
Q

which cestodes are transmitted by ingestion and cause tissue infection?

A
  1. T. solium (cysticercosis)

2. echinococcosis granulosus

42
Q

which parasite causes cysticercosis?

A

taenia solium = pork worm

43
Q

what is the life cycle of T. solium when it causes cysticercosis?

A
  1. eggs of gravid proglottids in feces and passed into environment
  2. embryonated eggs are ingested by human host in feces….
  3. oncospheres hatch, penetrate intestinal wall and circulate to masculature
  4. cysticerci may develop in any organ but as more common in subcutaneous tissues and the brain and eye
44
Q

what does cysticercosis cause?

A

caused by T. solium in tissues

common cause of seizures in developing countries

neurocysticercosis may account for at least 10% of seizures seen in some emergency departments and more than 2% of neurological or neurosurgical admissions

most persons who die from cysticercosis in the US are foreign born

45
Q

what are the symptoms of cysticercosis?

A

the most frequently reported tissue locations are skin, skeletal muscle -> do not cause symptoms.

asymptomatic subcutaneous nodules and calcified intramuscular nodules can be encountered

death can occur suddenly

extracerebral cysticercosis can cause ocular, cardiac, or spinal lesions with associated symptoms.

46
Q

what is cerebral cysticercosis?

A

aka neurocysticercosis

caused by T. solium

diverse manifestations including seizures, mental disturbances, focal neurologic deficits, and signs of space-occupying intracerebral lesions

47
Q

how do you diagnose cysticercosis?

A
  1. antibody detection: immUnoblot and enzyme immunoassays to T. solium
  2. biopsy of the effected area
  3. high IgE and eosinophils***
  4. CT scan, MRI or x-rays to detect the lesions
48
Q

how do you treat cysticercosis?

A

surgery –> removal of the cysticerci in the eye or in cases that are not responsive to drug treatment or to reduce brain edema

if asymptomatic, untrated larval infections often subside symptom wise within 2-5 years

49
Q

how do you treat neurocysticercosis?

A

symptomatic treatment with anti-seizure medication

or you can use antiparasite drugs like albendazole or mebendazole and anti-inflammatory corticoids and anticonvulsants (when needed)

50
Q

how do you prevent cysticercosis?

A

sanitation = Sanitation controlled disposal of human feces = keep out of water and vegetation!!

this is so important because the ONLY way to develop cysticercosis is to eat human feces contaminated with T. solium eggs

51
Q

what’s the common name for echinococcus granulosus?

A

hydatid worm

52
Q

what is the definitive host of echinococcus granulosus?

A

small intestine of dogs

53
Q

what is the intermediate host of echinococcus granulosus?

A

live stock = sheep, goat, swine

humans

54
Q

what disease does echinococcus granulosus cause?

A

it causes hydatid disease in humans

humans get echinococcosis disease by eating dog feces (eg. on contaminated food)

55
Q

what is the infection cycle of echinococcus granulosus?

A
  1. adult in small intestine of dog (definitive host)
  2. embryonated egg in feces

at this point a human could eat the egg in the feces (intermediate host) –> will cause cysts in liver, lungs, etc.

  1. sheep ingests eggs in feces (intermediate host)
  2. oncosphere hatches, penetrates intestinal wall
  3. hydatid cyst in liver, lungs
  4. dog ingests cysts in organs of dead infected sheep, goat, swine, etc.
  5. scolex attaches to intestine of dog
56
Q

what are the symptoms of echinococcus granulosus?

A

silent for years

hepatic involvement = abdominal pain, a mass in the hepatic area, and biliary duct obstruction

pulmonary involvement = chest pain, cough, and hemoptysis

rupture of the cysts can produce fever, urticaria, eosinophilia, increased IgE, and anaphylactic shock, as well as cyst dissemination

in addition to the liver and lungs, other organs may be affected (brain, bone, heart)

57
Q

how do you diagnose echinococcus granulosus?

A
  1. antibody detection –> Indirect hemagglutination (IHA), indirect fluorescent antibody (IFA) tests, and enzyme immunoassays (EIA)
  2. hydatid Cyst. ultrasonography and/or other imaging techniques supported by positive serologic tests
58
Q

how do you treat echinococcus granulosus?

A
  1. surgery to remove parasite mass (not usually 100% effective)

there’s also danger from potential of a ruptured cyst which could release antigen and cause shock

after surgery, use albendazole or mebendazole to keep the cyst from recurring

59
Q

how do you prevent echinococcus granulosus?

A
  1. denying sheep dogs access to carcasses of infected sheep
  2. obligatory testing and treatment of all sheep dogs
  3. prevention of contact of children with possibly infected sheep dog
  4. widespread education on the danger and method of spread of hydatid disease

ID Week 5 (13 decks)

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