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Parasitology > Chapter 12 > Flashcards

Chapter 12 Flashcards

1
Q

Why are nematodes important

A

they are very abundant, probably more than arthropods, 1/4 of the world suffers from infection, parasitize humans, animals and plants, destroy 10% of all crops

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2
Q

What is the outer layer/skin of nematodes called, what is it make of is it stronger or weaker than platyhelminth outer layer

A

cuticle, collagen, much stronger

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3
Q

What happens if you put a platyhelminth in broth, and nematodes?

A

platyhelminth- changes size due to absorption

nematode-no absorption

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4
Q

What are the parts of nervous systems do nematodes have

A

nerve ring on small ganglia in pharynx

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5
Q

Are nematodes coelomates or pseudocoelomates

A

pseudocoelomates meaning it has no true body cavity/coelom

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6
Q

What kind of muscles do nematodes have, what neurotransmitter do they use for contraction

A

excitatory-acetylcholine-contraction
inhibitory- aminobutyric acid-release
sodium/potassium channels

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7
Q

What drugs are best against nematodes and why, what other creatures do they work against

A

ivermectim-blocks channels and causes tetani in nematodes and arthropods

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8
Q

What kind of sensory organs do nematodes have

A

amphids- chemosensory organs, on each side of the head, used to sense and release sex pheromones
phasmids-for touch and sensing light and dark, used for orientation

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9
Q

What kind of guts do nematodes have, name their parts

A

psuedocoelom

mouth, buccal cavity, pharynx, intestine, rectum, anus, males have cloaca

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10
Q

Explain what a cloaca is

A

a common urogenital opening, the rectum and the vas differens both open into this cavity

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11
Q

Describe the characteristics of nematode intestines

A

one cell thick, no muscle coating surrounding it, pseudocoelomate, food is moved by body movement

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12
Q

what kind of osmoregulatory abilities do nematodes have

A

free living forms are osmoconformers
parasitic form is more limited
excretory products stored in pseudocoelom and become isotonic with surroundings.

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13
Q

What does a pseudocoelomate lack that an acoelomate has

A

inner mesoderm-the parenchyma

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14
Q

How are free living nemotodes different from parasitic nematodes

A

free living-very small usually, no buccal cavity, no bursa

parasitic-can get up to 10m long, has a buccal cavity, might have a bursa

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15
Q

Explain what the buccal cavity does

A

attach to the villi of SI, some have teeth to rasp off mucosa
blood feeding nematodes have pharyngeal glands that produce anti-coagulants to help blood flow

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16
Q

Explain what the bursa is

A

preset in male strongyloide nematodes, is around the cloaca, wraps around female, increases efficiency of fertilization

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17
Q

What are the characteristics of nematode life cycles

A 
They all have 4 larval stages and 4 molts
egg
Larvae 1- rhabdiform
molt 1 
larvae 2 
molt 2 
Larvae 3-filariform 
molt 3 
Larvae 4 
molt 4 
adult
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18
Q

When is the best time to kill a nematode (what stages)

A

L1, L2 or L3 because you can stop the molting process by using growth regulators, very hard to kill adults

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19
Q

What marks the nematode’s adulthood

A

mating

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20
Q

What makes the larvae stages different

A

mouthparts and habitats change with each form

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21
Q

What makes the larvae stages different

A

mouthparts and habitats change with each form

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22
Q

What does molting mean for nematodes

A

shedding of the cuticle and secretion of a new one

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23
Q

How are nematode juveniles and adults different

A

juveniles are smaller and have no gonads
usually have a different diet
adults no longer molt

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24
Q

What is the important characteristic of the third larval stage of nematodes

A

often the resting or resistant stage before reaching adulthood

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25
Q

What kind of sexes are nematodes? what type of sperm do they have?

A

always separate sexes, Males are smaller and have copulatory spicules, ameboid sperm

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26
Q

At what life stage are nematodes usually infective?

A

L3 stage, non feeding resistant stage

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27
Q

How is nematode egg production different to digeneans

A

no asexual reproduction so females are egg factories- 20K to 200K eggs/day

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28
Q

What parasite causes pinworms, what is the household way to test for it

A

enterobius vermicularis, scotch tape test

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29
Q

What are the characteristics of order strongylida nematoes

A

really big, usually infect domestic animals/ sometimes humans

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30
Q

What parasite causes hookworms

A

Necator americanus and Ancylostoma duodenale

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31
Q

Where are hookworms found in the world? in what environments

A

worldwide, moist, warm climate

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32
Q

What clinical issues do hookworms cause

A

iron deficiency due to anemia, cardiac complications, gastrointestinal and nutritional issues, ground itch, respiratory complications if pulmonary migration occurs

33
Q

What parasite causes ground itch, explain what causes it

A

hookworms, local skin infection during penetration of filariform L3

34
Q

What hosts do heomonchus contortus infect

A

grass eating animals like cattle and sheep

35
Q

How do people often get hookworms?

A

by being barefoot, eggs are in human feces

36
Q

How are hookworms IDed in the lab

A

eggs in stool under microscope

37
Q

What are the characteristics of order Ascaris lumbricoides

A

largest nematode to parasitize human intestines- up to 35cm long

38
Q

Where in the human body are ascaris lumbricoides found

A

adult in lumen of SI
eggs in feces or swallowed
larvae in intestinal mucosa
larvae mature in lungs, alveolar walls, go up bronchial trees, to throat, swallowed again,
get to small intestine, become adult worms

39
Q

What are the ideal environmental characteristics for ascaris lumbricoides eggs, how long does it take for eggs to embryonate

A

moist, warm, shaded soil, fertile eggs become infective after 18+ days

40
Q

How long do ascaris lumbricoides adult worms live

A

1-2 years

41
Q

What clinical symptoms does ascaris lumbricoides cause

A

stunted growth, abdominal pain, intestinal obstruction, pulmonary symptoms, worms might leave mouth (holy shit ew)

42
Q

How are ascaris lumbricoides IDed in the lab

A

eggs in stool under microscope

43
Q

What animals do Baylisacaris procyonis parasitize?

A

racoon roundworms, eggs can get eaten by mice, squirrels, beavers and humans

44
Q

How does Baylisascaris procyonis cause pathology in animals/humans, what name do these hosts have

A 
paratenic hosts (small mammals and birds)
larvae penetrate gut and migrate to tissues where they encyst, infect visceral organs, CNS and or eyes causing ocular larval migrans, can be asymptomatic or lethal
45
Q

Describe the life cycle of Trichinella spiralis / Trichina worm infection

A

transmitted when pigs/ other farm animals are fed meat scraps that are infected, can also be transmitted by rats, larva encyst in striated muscle of host and are released in SI

46
Q

What parasite is also called a whipworm

A

Trichuris trichiura

47
Q

Where in the human body are Trichuris trichiura

A

larvae in SI
adults in cecum
unembryonated eggs passed in feces
embryonated eggs ingested

48
Q

What other name does Loa loa have

A

African eye worm

49
Q

What vectors Loa loa

A

deer flies-day biters, Chrysops

50
Q

Describe the life cycle of Loa loa in humans

A

Deer fly bites human introduces L3 onto skin
larvae in subcutaneous tissue,
adults produce diurnal microfilariae

51
Q

Explain the how Loa loa migrate during the day and night

A

day-in peripheral blood

noncirculation phase-in lungs

52
Q

Describe the Loa loa life cycle in its vector

A

deer fly
ingests microfilariae, looses sheath and migrate from midgut to hemocoel to throacic muscle
third stage larva migrate to probiscis to get into human skin during blood meal

53
Q

What clinical symptoms does Loa loa cause

A

can be asymptomatic, might cause lymphatic dysfunction, elephantiasis
night cough and wheezing with fever
could cause ocular lesions that lead to blindness

54
Q

How are Loa loa IDed in the lab

A

microfilaria are found in a blood smear

55
Q

What vectors onchocerca volvulus

A

blackflies simulium

56
Q

What disease does onchocera volvulus cause

A

onchocerciasis, riverblindness

57
Q

Describe the Onchocerca life cycle in humans

A

L3 introduced to human skin by blackfly

larva develops in subcutaneous tissue into adult filariae, in nodules produces microfilariae

58
Q

How long de Onchocerca live

A

adults-15 years
produce microfilariae-9 years
microfilariae-2 years

59
Q

Where in the human body are Onchocerca usually found

A

skin. lymphatics of connective tissue

60
Q

Describe the Onchocerca life cycle in its vestor

A

blackfly-ingests during blood meal
microfilariae go to midgut, develop into L1-L3
Migrate to proboscis to reach human skin

61
Q

What pathology does onchocerca cause

A

loss of elasticity and pigment in skin
plugged up lymph vessels
blindness caused by migrating larva in cornea

62
Q

What disease does wuchereria bancrofti cause

A

brancroftian filariasis, elephantiasis

63
Q

What parasite causes filariasis/elephantiasis

A

Brugia malayi and Wuchereria bancrofti

64
Q

What disease does Brugia malayi cause

A

brugian filarisis, elephantiasis

65
Q

What vectors filariasis

A

culex, anopheles, aedes, mansonia and coquillettidia all mosquitoes

66
Q

Describe the life cycle of filariasis in humans

A

mosquito introduces L3 onto human skin
adults in lymphatics
produce nocturnal microfilariae
migrate to lymph and blood chanels

67
Q

What physical characteristic do filarial worms that help distinguish them

A

double uterus

68
Q

Describe the life cycle of filariasis in its vector

A

mosquito ingests microfilariae from blood meal, goes to midgut
L1-L3 in thoracic muscles
L3 migrates through hemocoel to probiscis to reach human skin

69
Q

What is the pathology of Filariasis

A

enlargement of lymph nodes, elephantiasis

70
Q

Describe the Dirofilaria life cycle

A

adult worms in RV and Pulmonary artery of dogs
microfilariae circulate blood
larvae develop in mosquito
mosquito can transmit to dogs and humans

71
Q

What vectors dirofilaria

A

mosquito Culex

72
Q

How long does it take for Dirofilaria to develop

A

180 days in dogs

never mature in humans

73
Q

What disease does dirofilaria immitis cause

A

canine heartworm

74
Q

What symptoms does Dirofilaria cause in humans and dogs

A

humans-asymptomatic, lesions in lungs seen in radiological exams, nodules caused by dead or dying worms that can become necrotic or calcified

75
Q

what disease does dracunculus medinensis cause

A

guinea worm, fiery serpent

76
Q

How is Drancunculus medinensis transmitted to humans

A

by drinking water contaminated with L3 copepods

77
Q

Explain the Drancunculus medinensis life cycle

A

human drinks contaminated water with copepods
larva released when copepods die
larva penetrate stomach and intestinal wall where they mature or reproduce
F migrate to skin and discharge larvae into water
copepod consumes larvae

78
Q

What symptoms does Drancunculus medinensis cause

A

blisters on skin, lesions on feet or legs.

worm emerging from legion

Parasitology (18 decks)

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