Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Infection and Immunity > 29 Helminths > Flashcards

29 Helminths Flashcards

1
Q

where is a parasite

A

live on or in a host organism and benefit by deriving nutrients at the other’s expense

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

where is an endoparasite

A

live within their host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is a helminth

A

parasitic organisms with worm-like anatomy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

examples of nematoda - nematodes

A

roundworms
hookworms
filaria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

examples of where trematoda - flukes infect

A

liver, blood, lung and intestinal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

examples of cestoda

A

tapeworms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

which are platyhelminths (flatworms)

A

trematoda

cestoda

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

which helminth causes high mortality

A

schistosomiasis worst

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what causes disease burden

A

Disease burden is not just about deaths – also the rate of infection

  • incidence of infection is very high for some helminth infections
  • e.g. ascariasis kills 60,000 but infected 900 million
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is morbidity

A

incidence of ill health within a population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what can cause great burden but not death

A

Chronic infections in particular can create a great burden through non-fatal ill-health
Lymphatic filariasis - blocking of the lymph nodes, inflammation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is DALY stand for

A

DALY = YLL + YLD

Disability-adjusted life years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is DALY

A

Number of productive years ‘lost’ due to disability or premature death (morbidity and mortality) expressed in the same unit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is DALY dependent on

A

Years of Lost Life (due to premature mortality)
Years Lost to Disability (due to injury or illness)
YLD = I x DW x L
Incidence in population
Disability Weight of specific condition
Average Length of time (years) until remission or death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is one DALY equivalent to

A

one year of healthy life lost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is helminths burden names

A

Neglected Tropical Diseases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

where do helminths diseases effect

A

Helminths burden is in low socio-economic countries

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what increases helminths infections

A

Increased sanitation removes a lot of these diseases

Warm climates required for a number of them either because

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

why can helminths infect better in warmer climates

A
  • a vector is required for them e.g. a flying insect /snail in water – required for lifecycle
  • hookworm require warm climate for larvae stage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are nematoda

A

Round worms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what have nematoda got

A

Have a proper mouth and anus – proper absorptive gut

Reproductive organs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

do nematoda have genders

A

dioecious (separate males and females) – they generally mate in the host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what do nematoda have on outside of cuticle

A

on their outside they have a tough cuticle: moults with growth; tough outer layer; environmental resistance in free-living relatives; glycoprotein/glycolipid coverage; interface with the immune system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the phylogeny of nematodes based on

A

18S sequences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what are there within the nematode phylogeny clades

A 
Within clades there are many free-living lineages 
Multiple lineages show parasitism with:
- Invertebrates
- Plants
- Vertebrates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is the most common drug used in against nematodes

A

albendazole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is the most common human infecting nematode

A

pinworm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what are the modes of transmission for common nematode parasites of humans

A

Those that infect us are mostly intestinal; many are transmitted by direct routes: ingestion or skin penetration, exit host faecally
Filaria nematodes transmitted by biting insects, not intestinal – direct through the bite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

how is ascaris spread

A

transmitted by SOIL ingestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

how does ascaris infect

A

ingestion of eggs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what is ascaris

A

soil transmitted nematode

example of roundworms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what is necator

A

soil transmitted nematode

example of hookworm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

how is necator transmitted

A

transmitted by skin penetration from SOIL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

how does necator infect

A

larvae skin penetration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

where is part of the development for soil transmitted helminths

A

in the soil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

why do soil transmitted helminths require warm climate

A

Eggs more resilient than larvae (even more so the hookworm as the larvae are more effected than the eggs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

what causes the burden of disease

A

Burden of disease greatest in conditions of poverty, largely due to:

  • poor sanitation
  • warm climate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

what does the soil transmitted helminths result in

A
  • stunting (nutritional burden as nematodes ‘steal’)
  • anaemia (particulary from hookworm)
  • diminished school performance (many years of lost schooling attributable to soil-transmitted helminths)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

what is Ascaris lumbricoides

A

giant round worm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

how is Ascaris lumbricoides transmitted

A

through eggs ingestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

what are the Ascaris lumbricoides hosts

A

humans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

what DALY does Ascaris lumbricoides cause

A

high mortality but higher incidence = high DALY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

how long can ascaris eggs persist in soil

A

eggs in soil infections after 2 weeks can persist for years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

how many eggs can females lay in ascaris lifecycle

A

Each adult female in host can lay 200,00 eggs a day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

how can humans get contaminated with ascaris

A

Humans contaminated through environment (hands feet in soil) lead to eating the helminths (in at the mouth and out at the anus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

what is the route that ascaris infect

A

‘direct route’ parasite; eggs ingested by human hosts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

what are the intermediate hosts

A

non

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

what does ascaris do inside the host

A

When in the body it does a lap of the body

  • larvae escape from intestine into bloodstream
  • migrate (via liver and heart) to lungs
  • leave bloodstream to escape into alveoli (grow here)
  • migrate up trachea (coughed up)
  • Swallowed back to intestine for maturation, mating and egg laying
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

why are encounters with the human immune system are complex

A

due to multiple:

  • growth stages (larvae, adults, eggs)
  • locations in the body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

how does larvae in ascaris lifecycle lead to pathology

A

Larvae: immune-mediated pathology e.g. eosinophilia, pneumonitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

how does adult ascaris lead to pathology

A
  • malnutrition
  • small bowel obstruction
    wandering Ascaris: biliary tract obstruction, pancreatitis, liver abscess
52
Q

what is the host for Necator americanus

A

humans

53
Q

how is Necator americanus transmitted

A

skin penetration by larvae

54
Q

what is Necator americanus

A

hookworm

55
Q

what do hookworms require in their lifecycle

A
  • filariform larvae need warm wet conditions

- hookworms gain access to host by burrowing into skin

56
Q

where do adults live in hookworm lifecycle

A

small intestine

57
Q

what do the adult hookworms do in the intestine

A

attach to intestine wall and take blood

30-200μL blood per day per hookworm

58
Q

what do hookworms cause

A

Intestinal blood loss + iron deficiency anaemia

59
Q

what interactions do hookworms have with host immune system

A
  • Transient (larvae) systemic

- Prolonged (adults) intestine

60
Q

what changes with hookworm infection as we age

A

Human burden of soil-transmitted nematodes with age
Even older people previously exposed to intestinal nematodes often do not mount a protective immune response – chronic and repeat infections common

61
Q

how are filarial nematodes transmitted

A

biting insects

62
Q

what can mosquitoes transmit

A

wucheria

63
Q

what is Wuchereria bancrofti

A

filarial roundworm

64
Q

what does the Wuchereria bancrofti infect

A

lymph system

65
Q

what is Wuchereria bancrofti vector

A

mosquito

66
Q

what is the Wuchereria route

A

caused by mosquito – straight into bloodstream

67
Q

what is the Onchocerca route

A

transmitted by blackfly – scratches at skin till blood comes out and starts to drink – within the skin

68
Q

how can onchocerca route cause blindness

A

if happens near eye = blindness

69
Q

what are platyhelminths

A

flat worms

largely free-living group

70
Q

what are neodermata

A

entirely parasite lineage

71
Q

where are human parasites

A

Eucestoda [Cestoda class] – common name tapeworms

Digenea [Trematoda class] – common name flukes

72
Q

what are trematoda like

A

Have mouth anus and intestine – not a proper absorptive intestine
Often hermaphroditic

73
Q

what is tegument

A

protective, but also highly dynamic – secretion, absorption of nutrients, glycocalyx, turnover

74
Q

what is the glycocalyx

A

Sugar coating – glycocalyx, don’t need to malt the same way nematodes do

75
Q

what are the 3 main blood fluke species infecting humans

A

Schistosoma mansoni
haemotobium
japonicum

76
Q

what do Schistosoma mansoni, haemotobium, japonicum cause

A

get a red rash where the snail enters the skin

77
Q

what is the host of Schistosoma mansoni, haemotobium, japonicum

A

snails

78
Q

how is Schistosoma mansoni excreted

A

excreted faecally

79
Q

how is haemotobium excreted

A

in urine

80
Q

how is japonicum secreted

A

faecally

81
Q

what do cercariae do

A

penetrate skin of humans who contact contaminated water

82
Q

what do larvae do in lifecycles of Schistosoma mansoni, haemotobium & japonicum

A

mature, mate in circulatory system (dioecious) & move to bowl or bladder venules

83
Q

where do the eggs go in the lifecycles of Schistosoma mansoni, haemotobium & japonicum

A

eggs move across the epithelium into the lumen of intestines or urinary bladder

84
Q

what is the problem with japonicum

A

zoonosis disease = more troublesome

85
Q

can humans get immunity to Schistosoma mansoni, haemotobium & japonicum

A

Humans can induce protective immunity to Schistosoma over time

86
Q

what are Th2 important for

A

clearance of helminth infections, characterised by IgE, IgA & eosinophils

87
Q

what is Treg important for

A

for resolving anti-Helminth inflammatory response

88
Q

what do immature Th0 do

A

cells can differentiate into number of different T helper cell types

89
Q

what are Th1 and Th17 used for

A

Th1 and Th17 can be treated as a combined pro-inflammatory force

90
Q

what do Treg cells do

A
  • Self-stimulation - TGF-β
  • Suppress activity of other Th types
  • Produce anti-inflammatory IL-10
91
Q

what do Th1 and Th2 release

A

release cytokines that reinforce response direction (IFN-γ, IL-4) – “self-stimulating”
=> response can be polarised towards (Th1 or Th17) or Th2

92
Q

what does the presence of helminths cause

A

elicits a strong Th2 response in host (IL-4 as marker)

93
Q

what is Th2 beneficial to

A

Th2 is beneficial to the host and parasite

94
Q

why is Th2 beneficial to host

A
  • lower Th1, less inflammation

- required for clearance

95
Q

why is Th2 beneficial to parasite

A
  • less cytotoxicity to kill them off
96
Q

why have we evolved to prevent Th1 response

A

prevent Th1 response as this would be more harmful than chronic illness being caused

97
Q

why is Th2 response referred to as quick and dirty

A

Th2-mediated tissue-repair allows tissue regeneration without excessive inflammatory tissue damage, BUT there is often scarring

98
Q

what do Th2 cells make

A

IL-4

IL-5

99
Q

what can IL-5 activate

A

eosinophils

100
Q

what can IL-4 activate

A

B cells, switch to producing IgE

101
Q

what does IgE bind to

A

a helminth antigen it recognises can bid to IgE receptor on eosinophils/mast cells
can signal downstream from these motifs

102
Q

when are eosinophils activated

A

Eosinophils effector cells are induced during helminth infections
Eosinophils activated by IL-5 in helminth infections

103
Q

how can eosinophils kill helminths

A

Signals from the eosinophil FceRI-IgE-helminth antigen trigger potential pathogen killing mechanisms

104
Q

what are the mechanisms that eosinophils do to kill helminths - schistosoma

A

attack a Schistosoma larva in the presence of infected patient serum in vitro

105
Q

what are the mechanisms that eosinophils do to kill helminths

A

vasodilation, neutrophil & eosinophil recruitment and activation of more eosinophils
IgE bound to helminth antigen

106
Q

how can IgE binding to helminth lead to helminth kills

A
  • Granules (enzymatic and nonenzymatic cationic proteins)

- Oxygen radical release (damaging to pathogens)

107
Q

what does the lack of schistosomiasis mean

A

For Schistosomiasis patients lack of reinfection DOES correlate with high peripheral blood eosinophils

108
Q

what makes IL-10

A

Treg

109
Q

what is the effect of modified Th2

A

generally reduce response to Tregs

- makelots IgG4

110
Q

effect of balanced Th1/Th2

A
  • more IgE

- still some IgG4

111
Q

effect of uncontrolled Th1

A
  • little IgG4

- more but not lots IgE

112
Q

what is the effect of modified TH2 response cytokines

A

HIGH IL-4, HIGH IL-10 and LOW IL-5 compared to balanced or TH1-dominant states

113
Q

effect on B cells in modified TH2 response cytokines

A

B cells make IgG4 (protects from over inflammation, doesn’t activate complement – no immune response)

114
Q

how is inflammation reduced in modified TH2 response cytokines

A

absence of high levels of IgG, Treg are making IL-10, the IL-10 inhibits the IgE and allows IgG4 to dominate = reduce eosinophil activation and increases IgG4, reduces inflammation

115
Q

how do helminths actively modulate adaptive immune response

A

secrete a range of substances that modulate immune system

  • cytokine mimics (e.g. TGF-β-mimics)
  • non-protein signatures (e.g. host-like glycans & phospho-lipids) – hiding!
  • protease inhibitors
116
Q

how do protease inhibitors modulate adaptive immune response

A

cystatins block inflammatory signalling cascades

117
Q

what do helminths secrete that modulate immune effectors

A
  • proteases and anti-oxidant enzymes

- protease inhibitors

118
Q

what do protease and anti-oxidant enzymes do

A

block Eosinophil recruitment and killing

119
Q

what do protease inhibitors do

A

serpins block neutrophil secreted proteases

120
Q

what are the disadvantages of immunoregulation by helminths

A

require a strong Th1 response for:

  • fight bacterial, viral and protozoal infections – which can be downregulated by helminth infection
  • fight tumours, reduced anti-tumour immunity
  • vaccines usually require Th1 mediated response, and high IgG levels = reduced efficacy
121
Q

what are the benefits of immunoregulation by helminths

A

Anti-inflammatory activity for

  • asthma
  • autoimmune diseases
  • inflammatory bowl disease
122
Q

what will helminths possibly be used for in the future

A

Helminth-derived products may be the anti-inflammatories of the future

123
Q

what are Schistosoma eggs like

A

highly immunogenic

124
Q

what does SEA stand for

A

Schistosoma egg antigen

125
Q

what does SEA do

A

recruits immune cells (Th2-mediated) = Granuloma

126
Q

where does the granuloma form

A

Body ‘pushes’ granuloma across intestine or bladder wall to expel

Infection and Immunity (29 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions