Parasitology Exam 2 Flashcards

1
Q
  • eggs can be mamalated (bumpy) or smooth when fertilized
  • eggs are barrel-shaped when unfertilized
  • requires both male and female worm present to fertilize
A

Ascaris lumbricoides

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2
Q

Ascaris lumbricoides: Diagnostic and Infective

A

Diagnostic: eggs
Infective: eggs

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3
Q
  • eggs have “flat football” appearance (one flat side)
  • eggs collected from the peri-anal area with a sticky-sided spatula
A

Enterobius vermicularis (Pinworm)

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4
Q

Enterobius vermicularis: Diagnostic and Infective

A

Diagnostic: eggs
Infective: eggs

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5
Q
  • eggs have distinctive “polar plugs” and are barrel-shaped
  • light amber color on bile stain
A

Trichuris trichuria (Whip worm)

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6
Q

Trichuris trichuria: Diagnostic and Infective

A

Diagnostic: eggs
Infective: eggs

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7
Q
  • eggs have granular cluster of larvae with visible space between them and the cell wall
  • two organisms have the same egg morphology
A

Ancylostoma duodenale (Old World Hookworm)
Necator americanus (New World Hookworm)

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8
Q

Hookworm: Diagnostic and Infective

A

Diagnostic: eggs
Infective: filariform larva penetrates skin

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9
Q

“Worm burden”

A

a measure of how many hookworms are in the gut, can relate to the severity of iron deficiency anemia that may develop from chronic bleeding

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10
Q

Differences in adult hookworm morphology

A
  • Ancylostoma duodenale has 2 pairs of teeth for attachment
  • Necator americanus has two cutting plates for attachment
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11
Q

Differences between strongyloides and hookworm rhabditiform larvae

A
  • Strongyloides has short buccal cavity
  • Hookworm has long buccal cavity
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12
Q

Which nematode can cause autoinfection?

A

Strongyloides stercoralis

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13
Q

Strongyloides stercoralis: Diagnostic and Infective

A

Diagnostic: rhabditiform larvae
Infective: filariform larva penetrates skin

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14
Q

Usually obtained from infected animal tissue, especially raw pork. “Wood knots” appearance in tissue

A

Trichinella spiralis

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15
Q

Trichinella spiralis: Diagnostic and Infective

A

Diagnostic: Larvae in tissue
Infective: encysted larvae in undercooked meat

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16
Q

Adult worm releases larvae from a blister on the leg or foot. Eliminated by slowly winding on a stick.

A

Dracunulus medinensis

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17
Q

Dracunulus medinensis: Diagnostic and Infective

A

Diagnostic: Blister bursting
Infective: ingesting copepods in water

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18
Q
  • Causes elephantiasis of the lower extremities
  • Microfilariae in the blood have a sheath, but no nuclei in the tip of the tail
A

Wucheria bancrofti

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19
Q

Wucheria bancrofti: Diagnostic and Infective

A

Diagnostic: microfilaria in blood
Infective: skin penetration of microfilariae by insect vector (Anopheles)

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20
Q
  • Causes elephantiasis of the lower extremities
  • Microfilariae in the blood have a sheath and 2 terminal nuclei in the tail
A

Brugia malayi

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21
Q

Brugia malayi: Diagnostic and Infective

A

Diagnostic: microfilaria in blood
Infective: skin penetration of microfilariae by insect vector (Anopheles)

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22
Q
  • Microfilariae in the blood have a sheath and nuclei are continuous to tip of the tail
A

Loa Loa (eye worm)

23
Q

Loa Loa: Diagnostic and Infective

A

Diagnostic: Calibar swelling (nodules), seeing worm migrate
Infective: Larvae are spread by insect vector (sandfly, deerfly, chrysops)

24
Q
  • Causes “River blindness”
  • Subcutaneous nodules known as “ochocercoma” where the adult lives
  • Microfilariae in the blood have NO sheath, nuclei do NOT extend to tip of tail
A

Onchocerca volvulus

25
Q

Onchocerca volvulus: Diagnostic and Infective

A

Diagnostic: biopsy skin snips of nodule
Infective: larvae spread by bite of gnat

26
Q
  • Cause largely asymptomatic filarial roundworm infections
  • Inhabit body cavities
  • Spread by insect vector
A
  • Mansonella ozzardi (unsheathed, no nuclei to tip of tail)
  • Mansonella perstands (unsheathed, nuclei extend to tip of tail)
27
Q
  • Eggs have a “ruffled edge” appearance
  • Eggs are almost circular
  • Eggs are thick-walled, have 3 pairs of hooklets for attachment
A

Taenia (saginata and solium, egg can’t be distinguished)

28
Q

Taenia: Diagnostic and Infective

A

Diagnostic: Egg or proglottid in stool
Infective: Encysted larva in undercooked meat

29
Q

Taenia saginata morphology

A
  • Proglottids are longer than wide
  • Proglottids have15-20 uterine branches/side
  • Adult scolex has 4 suckers, no hooks (unarmed)
30
Q

Taenia solium morphology

A
  • Proglottids are longer than wide
  • Proglottids have <13 uterine branches/side
  • Adult scolex has 4 suckers, with hooks (armed)
31
Q

Which cestode can encyst in other parts of the body (cysticercosis)?

A

Taenia solium

32
Q
  • Egg is 30-50 um
  • Egg has hooked oncosphere
  • Egg has polar filaments
A

Hymenolepis nana (dwarf tapeworm)

33
Q
  • Egg is 60-80 um
  • Egg has hooked oncosphere
  • Egg has NO polar filaments
A

Hymenolepis diminuta (rat tapeworm)

34
Q
  • Tapeworm commonly infects dogs and cats
  • Forms characteristic egg packets (8-15 eggs)
  • Egg packets measure 25-40 um
A

Dipylidium caninum

35
Q
  • adult has spoon-shaped scolex
  • Proglottids are wider than long, central uterine pore
  • Egg has lidded operculum, terminal knob on avoperculum
A

Diphyllobothrium latum (fish tapeworm)

36
Q

Diphyllobothrium latum: Diagnostic and Infective

A

Diagnostic: egg
Infective: cysts in undercooked fish

37
Q

What cestode can lead to megaloblastic anemia due to B12 deficiency?

A

Diphyllobothrium latum

38
Q
  • normal life cycle involves dogs and sheep
  • forms hydatid cysts filled with hydatid sand in tissues of humans
A

Echinococcus granulosus

39
Q

What happens if a hydatid cyst bursts during surgical removal?

A

Dissemination of the daughter cells within, possible anaphylaxis if cyst leakage has previously stimulated an IgE response

40
Q

Echinococcus granulosus: Diagnostic and Infective

A

Diagnostic: Cyst
Infective: Egg

41
Q
  • Self-resolving itchy skin after contact with water
A

Schistasome Dermatitis, aka “swimmer’s itch”. Caused by avian schistosomes that can’t penetrate deeper than the skin

42
Q
  • Egg shows a terminal spine
  • Leading cause of bladder cancer in Egypt
  • Lives in blood vessels supplying the bladder
A

Schistosoma haemotobium (bladder fluke)

43
Q

Schistosoma haemotobium: Diagnostic and Infective

A

Diagnostic: Eggs found in URINE
Infective: Cercariae penetrates skin

44
Q
  • Intestinal schistosome
  • Egg has large lateral spine
  • Egg is large (160x80 um)
A

Schistosoma mansoni

45
Q

Schistosoma mansoni: Diagnostic and Infective

A

Diagnostic: egg in stool
Infective: Cercariae penetrates skin

46
Q
  • Intestinal schistosome
  • Egg has small lateral spine (can be hard to see)
  • Egg is small (80x90 um)
A

Schistosoma japonicum (Oriental Blood Fluke)

47
Q

Schistosoma japonicum: Diagnostic and Infective

A

Diagnostic: egg in stool
Infective: Cercariae penetrates skin

48
Q
  • Large operculated egg (55x85 um)
  • Shouldered operculum
A

Paragonimus westermanni (Oriental Lung Fluke)

49
Q

Paragonimus westermanni: Diagnostic and Infective

A

Diagnostic: egg seen in SPUTUM
Infective: eating cysts in undercooked crayfish

50
Q
  • Very large operculated egg (150x90 um)
  • Densely granulated egg, amber color
A

Fasciola hepatica (Sheep Liver Fluke)
or
Fasciolopsis buski (Intestinal Fluke)

51
Q

Fascioloa hepatica: Diagnostic and Infective

A

Diagnostic: egg in stool
Infective: Eating cysts in contaminated watercress

52
Q

Fasciolopsis buski: Diagnostic and Infective

A

Diagnostic: egg in stool
Infective: Eating cysts in contaminated water chestnuts

53
Q
  • tiny egg (30x16 um) with shouldered operculum
  • egg has terminal knob (not always visible)
  • smallest fluke
A

Clonorchis sinensis (Chinese Liver Fluke)