L15 Helminths Flashcards
1
Q
what are endoparasites
A
single celled protozoa
or multiple celled
2
Q
what are examples of multicellular animals
A
trematoda (flukes)
cestoda (tapeworms)
nematoda (nematodes_
3
Q
what are the platyhelminths
A
flat worms
- tremadtoda
- cestoda
4
Q
what is the the prevalence of disease and deaths with helminths
A
not the most deaths but very prevalent
not all just about deaths when it comes to disease
5
Q
what are the human ‘worm’ parasites
A
round worms
flat worms
6
Q
what is the generalised anatomy of nematodes
A
cuticle - tough outer layer
glycoprotein/glycolipid coverage
7
Q
what is the cuticle for in nematodes
A
environmental resistance in free-living relatives
8
Q
what is the glycoprotein/glycolipid for in nematodes
A
often immunogenic
9
Q
where do nematodes mate
A
generally in the host
10
Q
how do nematodes mate
A
they are dioecious - have male and female organs
11
Q
what is the phylogeny of nematodes
A
many free-living lineages multiple lineages show parasitism with: - vertebrate - invertebrate - plant significant parasites of man in several line
12
Q
how are some nematode parasites transmitted by ingestion
A
ingestion of eggs
eat infected host
ingestion of larvae
ingestion of larvae (in host)
13
Q
how are nematode parasites - filaria transmitted
A
mosquito
black fly
deer fly
midge
14
Q
what are the most direct routes that the nematode parasites infect
A
ingestion or skin penetration
15
Q
how long is soil transmitted helminths in the soil until they are infective
A
3-4 weeks
16
Q
how does soil transmitted helminths infect
A
via eggs in contaminated soil or skin penetration
17
Q
examples of soil transmitted helminths that infect via contaminated soil
A
ascaris
trichuris
18
Q
examples of soil transmitted helminths that infect via skin penetration
A
hookworm
19
Q
what is the environment soil transmitted helminths require
A
warm wet
20
Q
where are soil transmitted diseases the biggest burden
A
poverty
poor sanitation
21
Q
how does trichuris infect
A
direct
22
Q
what is the lifecycle of trichuris
A
infected
live in gut and expelled as eggs
into soil and taken back up
23
Q
what is the adult habitat of trichuris
A
caecum, colorectum
24
Q
what is the lifespan of trichuris
A
1-3 years
25
what does trichuris infection cause
90% asymptomatic
26
what is ascaris lumbricoides known as
giant roundworm
27
what is trichuris trichiura known as
whipworm
28
what is the lifecycle of ascaris
eggs ingested
larvae escape from intestine
in bloodstream go to liver then heart then lungs
escape into alveolae
migrate up trachea
brought up in mucus and then swallowed again = back to intestine where adults made
29
how many eggs do ascaris lay a day
200,000
30
when is the ascaris associated with pathology
migration and adult ascaris
31
what do the larvae of ascaris cause
eosinophilia
| pneumonitis
32
what do the adults of ascaris cause
malnutrition
small bowel obstruction
wandering Ascaris: biliary tract obstruction, pancreatitis, liver abscess
33
what is the effect of acaris
high killing - high morbidity
34
what is necator americanus known as
new world hookworm
35
how do hookworms gain access into the host
larvae in soil climb vegetation, sense warm blooded animals, attach to skin and burrow through skin into blood stream
36
how much blood do hookworms take a day
30-200ul
37
what do hookworms cause
intestinal blood loss
| iron deficiency - anaemia
38
where do adult hookworms live
small intestine
39
what do adult hookworms do
attach to intestine wall & take blood
40
hookworm lifecycle
```
burrow into skin
migration via lungs
larvae migrate to trachea
swallowed
adults in small intestine
eggs in faeces
```
41
what is different about the hookworm lifecycle
double route
42
what are wuchereia bancrofti known as
filarial roundworm
43
what is the vector of wuchereia bancrofti
mosquitos
44
what are the hosts of wuchereia bancrofti
humans
45
what are the hosts of necator americanus
humans
46
what is the transmission of necator americanus
skin penetration
47
what are the hosts of ascaris lumbricoides
human
48
what are the hosts of trichuris trichirua
human
49
what is the transmission of trichuris trichirua
ingestion of eggs
50
what is the filarial lifecycle
transmitted by biting fly
adults migrate to lymphatics (Brugia, Wuchereria)
or develop in skin
mate and produce live young (microfilariae) – circulate in blood
51
what is the mortality like of lymphatic filariasis and onchocerciasis
low
52
what is the morbidity like of lymphatic filariasis and onchocerciasis
high
53
what are the human parasites of platyhelminths
digenea - trematoda
| eucestoda - cestoda
54
what is the lineage of platyhelminths
largely free living group
55
what is the lineage of neodermata
entirely parasitic lineage
56
what is the generalised morphology of platyhelminths - trematoda
attachment structures
digestive sac
tegument
57
what is the generalised morphology of platyhelminths - cestoda
attachment structures
58
what is the tegument function for the platyhelminths
protective
highly dynamic
absorption of nutrients
secretion/turnover of glycocalyx
59
how do tapeworms absorb nutrients
lost intestines
| only via skin
60
what is the generalised morphology of trematodes
blind sac intestine
mouth
intestines
eggs coiled in uterus
61
what is the intestine of trematode like and why
very reduced intestine so body can fill with eggs/teste to reproduce
62
how are human infecting trematodes catergorised
by sites of infection/disease
63
how many people suffer from liver or lung fluke infections from trematodes
around 40-100 million
64
how many people suffer from schistosoma - trematodes
around 600 million infected
| 250,000 mortality per annum
65
what are schistosoma mansoni, haemotobium, japonicum known as
blood fluke
66
what are the schistosoma mansoni, haemotobium, japonicum hosts
snails
| humans
67
what is the lifecycle of schistosoma spp.
cercariae burrow through skin of humans larvae mature and mate in the circulatory system (dioecious)
eggs move to the intestines or the urinary bladder
68
where do schistosoma spp. infect
contact contaminated water
69
what are the cestode specialisations
```
no digestive system
segmented body (strobila)
```
70
how do cestodes absorb nutrients without a digestive ssytem
through cuticle
71
what is the function of the cestode segmented body (strobila)
release of mature segments (proglottids) transmits eggs to faeces
72
what is taenia saginata known as
beef tapeworm
73
what are the hosts of taenia saginata
cattle
| humans
74
what is the generalised cestode lifecycle
```
develop in intermediate host in tissues
taken up by predator (human) eating contaminated food from undercooked meat
eggs hatch in intestine
eggs made
passed out in faeces
```
75
where are the taenia human cestodes as adults
attach to intestinal epithelium
76
what do echinococcus human cestodes infect
humans are accidental intermediate hosts
77
how are humans infected by echinococcus human cestodes
food/water contaminated from dog faeces
78
what is the zoonosis of echinococcus human cestodes
larvae create cysts in tissue as intermediate host
79
what does echinococcus human cestodes cause
hydatid disease
80
what can taenia human cestodes cause
nutritional burden
| intestinal blockage if tapeworm large
81
what do Th0 cells become
differentiate into number of different T helper cell types
82
what are the major types of T helper cells
Th1
Th2
Th17
Treg
83
what causes the Th0 differentiation direction
direction comes from cytokines and interaction with dendritic cells
84
what do th1 and th2 release
cytokines
85
what do cytokines do
that reinforce response direction (IFN-γ, IL-4)
86
what is the th1/th2 polarisation
Th1/Th2 inhibit each other = response can be polarised towards Th1 or Th2
87
what is the effect of Treg cells
suppress activity of other Th types (calming effect)
88
what do Treg cells make
anti-inflammatory IL-10
89
what induces Treg
TGF-β
90
what does the presence of helminths cause
elicits a strong Th2 response in host
| create Th2 polarisation
91
what is the effect of th2 in host
beneficial
| lower Th1, less inflammation
92
what is the effect of th2 in parasite
beneficial
| less cytotoxicity
93
how can Th2 be measured
IL4 is a marker for Th2 response
94
what do helminths secrete
- cytokine mimics
- non-protein signatures
- protease inhibitors
- antioxidants
95
what do protease inhibitors do
block inflammatory signalling cascades
96
examples of protease inhibitors
cystatins/serpins
97
examples of cytokine mimics
TGF-β-mimics
98
examples of non-protein signatures
host-like glycans
99
what is the function of anti oxidants
block cytotoxic killing
100
effect of immunosuppression and th2 polarisation
greater susceptibility to microbes
| reduced efficacy of vaccines
101
what is required due to greater microbe susceptibility
require th1 response
102
what is required due to reduced efficacy of vaccines
helminth burden serious issue for success of vaccine trials into neglected tropical diseases
may need to pre-treat with anti-helminthic
103
what are the soil transmitted helminths
ascaris
hookworm
trichuris
104
what are the filarial nematodes
filarial roundworm
105
what are the platyhelminths
trematoda
| cestoda
106
what are the trematoda
schistosoma spp.
107
what are the cestoda
taenia saginata
| cestode
