Helminths (complete) Flashcards

(101 cards)

1
Q

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

A

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

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2
Q

What are helminths

A

macroscopic, eukaryotic, multicellular worms

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3
Q

can the larvae of helminths typically support themselves?

A

no, they typically need support from intermediate hosts

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4
Q

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

A

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

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5
Q

What types of helminths are dioecious

A

blood flukes and nematodes

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6
Q

What types of helminths are monecious

A

all helminths except blood flukes and nematodes

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7
Q

Cestodes and trematodes are both platyhelminths, what does that mean

A

that they are flatworms

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8
Q

how long do helminth infections last

A

usually years

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9
Q

What is the immune response generated by helminths

A

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

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10
Q

How well does the immune system work against helminths

A

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

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11
Q

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

A

Intestinal helminths = anemia from chronic blood loss

Systemic helminths = organ damage from inflammatory responses to eggs or worms

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12
Q

What are some of the larger problems caused by helminths

A

liver failure
epilepsy
elephantitis

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13
Q

do helminths generally replicate in mammalian hosts?

A

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

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14
Q

do helminth infections have a high morbidity rate

A

yes

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15
Q

What are the three ways helminths can enter the body

A

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

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16
Q

Where in the body do helminths localize

A
liver, lungs, intestines, CNS
Dermal and lymph tissue
Blood vessels (around intestine and bladder)
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17
Q

What are the two ways helminths directly cause damage

A

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

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18
Q

What is the beef tapeworm

A

taenia sangiata

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19
Q

what is the pork tapeworm

A

taenia solium

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20
Q

Which humans have the high incidence of infection with Taenia

A

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

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21
Q

How do the cattle and swine get infected with taenia

A

by eating contaminated vegitation

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22
Q

What is Cysticerci

A

the larvae of helminths in meat

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23
Q

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

A
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)
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24
Q

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

A

they are released into the feces

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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