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Flashcards in Helminths (complete) Deck (101):
1

What are the three categories of helminths that are pathogenic to humans

Cestodes (tapeworms)
Trematodes (flukes)
Nematodes (roundworms)

2

What are helminths

macroscopic, eukaryotic, multicellular worms

3

can the larvae of helminths typically support themselves?

no, they typically need support from intermediate hosts

4

What does it mean that helminths can be dioecious or monoecious?

Dioecious means that there are male and female worms that need to "get together" to reproduce
monoecious means that the worm has both male and female sex organs

5

What types of helminths are dioecious

blood flukes and nematodes

6

What types of helminths are monecious

all helminths except blood flukes and nematodes

7

Cestodes and trematodes are both platyhelminths, what does that mean

that they are flatworms

8

how long do helminth infections last

usually years

9

What is the immune response generated by helminths

a TH-2 immune response with eosinophilia, mucosal mastocytosis, and elevated IgE

10

How well does the immune system work against helminths

it struggles to completely eliminate the helminths, and reinfections are common, but the parasite load does decrease over time reflecting partial immunity

11

What are the two different places you find helminths in the body, and what are the problems they cause

Intestinal helminths = anemia from chronic blood loss
Systemic helminths = organ damage from inflammatory responses to eggs or worms

12

What are some of the larger problems caused by helminths

liver failure
epilepsy
elephantitis

13

do helminths generally replicate in mammalian hosts?

nope, passage through intermediate hosts of through soil and water is required

14

do helminth infections have a high morbidity rate

yes

15

What are the three ways helminths can enter the body

through the mouth
bite of insect vector
penetration (burrowing through skin)

16

Where in the body do helminths localize

liver, lungs, intestines, CNS
Dermal and lymph tissue
Blood vessels (around intestine and bladder)

17

What are the two ways helminths directly cause damage

They cause cysts to grow in organs which damages them by putting pressure on them
they physically block intestines

18

What is the beef tapeworm

taenia sangiata

19

what is the pork tapeworm

taenia solium

20

Which humans have the high incidence of infection with Taenia

those working in close proximity to livestock (cows and pigs)

21

How do the cattle and swine get infected with taenia

by eating contaminated vegitation

22

What is Cysticerci

the larvae of helminths in meat

23

What are the body parts of Cestodes (tapeworms - taenia)

Scolex - point of attachment
chain of proglottids
Those near the scolex are immature
those near the middle are mature
those near the end are gravid (full of fertilized eggs)

24

What happens with the gravid proglottids (gravid meaning full of fertilized eggs)

they are released into the feces

25

How many proglottids can a mature T. sanginita worm have, and how many eggs does each have

they can have 1-2000 proglottids, each of those having about 100,000 eggs.

26

how many proglottids do infected humans pass per day

6

27

Where do the taenia attach

the intestinal epithelium

28

do most humans infected with taenia have symptoms

nope, they just shed proglottids (they only have symptoms if the worm gets large enough to block the intestines)

29

How do you prevent taenia infection

thoroughly cooking or freezing meat

30

How large can taenia sanginita become

10 meters long

31

does the scolex of taenia sanginita have hooks

nope

32

what happens to the proglottids of taenia sanginitia

they are relesed into feces, then the eggs develop into onchospheres, which leave animal intestines and encyst into animal tissues. They develop there into cysticerci, which are ingested, then develop into adult worms

33

What is the treatment for taenia sanginata

niclosamide or PTZ

34

Can humans become the intermediate host of taenia solium

yes, but this is rare because the cysticerci develop in the human muscle, but this is a dead end for the taenia solium because the human tissue doesn't get eaten

35

can cysticerci in humans be pathogenic

yep, it can develop in the eye, CNS, and the heart

36

What can cysticerci in the CNS (neurocysticerosis) cause

epilepsy, meningitis, and encephalitis

37

how can neurocysticerosis be diagnosed

biopsy, CAT scan, MRI, look for subcutaneous cysticericosis first

38

how are cysticercosis treated

phenothiazine (PTZ)
corticosteroids
surgery

39

What are echinococcus granulosus

tapeworms of canines

40

how many proglottids do echinococcus granulosus have

3, one immature, one mature, and one gravid (each time the neck forms a new proglottid the gravid one falls off)

41

how are canines infected by echinococcus granulosus

by eating cysticerci in various herbivore hosts

42

what happens to humans with echinococcus granulosus

they can become accidental intermediate hosts if they ingest something contaminated with dog feces. they get Hydatid Disease

43

What is hydatid disease

an infection of echinococcus granulosus cysticerci. those cysticerci can grow and form hydatid cysts, this can cause tissue disfunction and if there are large numbers, death

44

What are trematodes

flukes, flat and leaf-shaped worms

45

what are the suckers like on trematodes

there are oral and ventral suckers that allow for attachment and nutrient obtaining

46

are trematodes dioecious or monoecious

they can be either

47

What is the most important trematode infector of humans

Schistosoma

48

how does a human infection of Schistosoma occur

motile cercariae in contanimated fresh water penetrate intact skin with the proteases stored in their head. Then they lose their tails and migrate via the circulation to the liver

49

where do Schistosoma mature

in the liver

50

do Schistosoma multiply in the host

nope, they do release eggs however

51

what do the eggs of Schistosoma elicit from the immune system

a granulomatous inflammatory response

52

What is another name for schistosoma

blood flukes

53

are blood flukes dioecious or monoecious

dioecious

54

What disease do blood flukes cause

schistosomiasis

55

What are the three species of Schistosoma

Schistosoma mansonii
Schistosoma haemotobium
Schistosoma Japonicum

56

does anything occur where a cercariae enters the skin

sometimes dermatitis

57

how serious can blood flukes be

they can become chronic and fatal

58

how do you prevent blood flukes

improved sanitation and avoiding contact with contaminated water

59

how do Schistosoma worms evade the immune system

by absorbing host complement regulatory proteins onto their surface

60

What is acuter Schistosomiasis

(katayama fever)

61

What does an early immune response to Schistosoma demonstrate

Th1

62

What is the overall immune response to Schistosoma

Th2, eosinophilia, elevated IgE, type 2 granulomas surrounding the eggs

63

What characterized a type 2 granuloma

TH2 cells, eosinophilias, macrophages, and fibroblasts

64

What can the type 2 granulomas caused by blood flukes do the tissue in which they are

they are in the liver, and they can block the liver sinusoids and impede blood flow. this can eventually lead to Cirrhosis

65

What are nematodes

long cylindrical worms with tapered ends, and complete digestive tracts

66

are nematodes dioecious or monoecious

dioecious

67

What are the reproductive strategies of nematodes

1. shed eggs into lumen of the intestine (fecal-oral transmission)
2. shed eggs into the soil (larvae penetrate skin)
3. encyst in muscle tissue (eaten if undercooked)
4. mosquitos

68

Which nematode infection is the most common and which nematode is the largest to infect humans

Ascaris lumbricoides (both most common and largest)

69

where do in Ascaris lumbricoides an endemic

the SE US

70

where do Ascaris lumbricoides reproduce

the small intestine

71

what happens to ingested Ascaris lumbricoides

the larvae enter the blood, go to the lungs, get coughed up and swollowed, mature in intestine

72

What happens when Ascaris lumbridoides migrate through the lung

you get loefflers sydrome = eosinophilic pneumonitis

73

What happens when Ascaris lumbricoides live in the GI

pain, diarrhea, intestinal obstruction

74

what happens when Ascaris lumbricoides live in the pancreatic liver or ducts

it is life threatening

75

What are the problems with Ascaris lumbricoides

the migrating larvae (int - blood - lungs - sto - int)
- potent allergies
- ascaris pneumonia
- asthma
Undernourishment
abdominal pain, eye pain, asthma, insomnia
death (if they block the intestines)
penitration to peritoneum
wandering worms

76

what causes Ascaris lumbricoides to wander

the female wants to burrow in the male, if it can't find one the female begins to borrow

77

Where can Ascaris lumbricoides worms end up

intestines
liver
lungs
in feces
stomatch (puked out)
esophagus, trachea

78

how is a Ascaris lumbrcoides infection diagnosed

barium enema
juveniles in sputum

79

how is an Ascaris lumbricoides infection treated

Mebendazole

80

What is the sceintific name for the whip worm

Thrichuris trichuria

81

What is the cycle of a whip worm infection

eggs to soil to mouth, hatching to adults in intestine, thread through the mucosa

82

How does thrichuris trichuria cause pathologies

due to the worm burden, more than 100 worms

83

What are the problem a whip worm infection can cause

death (if the worm burden is high)
dysentery
anemia
growth retardation
tenesmus
prolapsed rectum

84

What is the second most common nematode infection

hook worms

85

what are the two types of hookworms that infect humans

ancylostoma duodenale
necator americanus

86

what is the infectious life cycle of hookworms

larvae in soil
burrow through skin
carried in blood to heart and lungs
in lungs they burrow in the mucosa and migrate up and get swallowed
in the intestines the attach, feed on blood, mature and mate

87

how is a hookworm infection treated

albendazole

88

how is a hookworm infection prevented

by wearing shoes

89

What is the common name for enterobius vermicularis

the pinworm

90

what is the most common parasitic worm in the US

the pinworm (humans are the only host for the enterobius)

91

where do female pinworms lay their eggs

around the anus

92

what is the main symptom caused by pinworms

intense perianal intching

93

how are pinworm infections prevented

preventing fecal oral spread (itching of the anus - worms under fingerails)

94

what is the scotch tape diagnosis for

enterobius vermincularis

95

What is the causitive agent of filariasis

wuchereria bancrofti

96

Where do the wuchereria bancrofti typically infect

lymph tissue and subcutaneous tissue

97

How is wuchereria bancrofti transmitted

female mosquitoes of some sort, they get the immature forms from one human, then pass them to another in its next form

98

What are the initial symptoms of lymphatic filariasis

it is typically initially asymptomatic

99

what is the end result of lymphatic filariasis

elephatiasis

100

what is elephantiasis

when lymph becomes blocked and pools up in the cutaneious and subcutaneous areas, they get swollen and hardened

101

how do you prevent wuchereria bancrofti infection

avoiding infected mosquitoes