AB L2 Helminths Flashcards

1
Q

What are helminths?

A

Multicellular, with differentiated organs

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2
Q

Do helminths have a circulatory tract?

A

No

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3
Q

Size?

A

<1nm - 10m

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4
Q

Anterior end has…

A

suckers, hooks or plates for attachment

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5
Q

Where do helminths replicate?

A

Usually free or in another host, they don’t live their whole lives in humans

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6
Q

Why is is difficult for the immune system to eradicate them? (2)

A

Have a tough cuticle

Some camouflage by coating with host molecules (e.g. roundworms)

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7
Q

Parasitic helminths feed on…. (2)

A

Body fluids or intestinal contents

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8
Q

WHO status of helminths:

A

Many are neglected tropical diseases

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9
Q

Mainly found in what populations?

A

Rural villages/overcrowed cities

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10
Q

Symptoms include….

A

malnutrition affecting physical and mental development

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11
Q

Apary from health why else are helminths an issue?

A

economic cost - e.g. infected cattle

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12
Q

Main classes of helminths

A

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

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13
Q

What to nematodes (roundworms) look like?

A

cylindrical body - no shit.

have alimentary canal - food comes in one side and out the other

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14
Q

What do cestodes look like?

A

flat, ribbon shape

no digestive tract, nutrients absorbed through the cuticle

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15
Q

What do trematodes look like?

A

leaf-shaped

blind-branched alimentary tract (in one end, out the same end)

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16
Q

4 e.g. of intestinal nematodes

A

large roundworm
threadworm
hookworm
whipworm

17
Q

Most intestinal nematodes are transmitted via …

A

fecal-oral route

although hookworm larvae penetrate the skin

18
Q

Symptoms of intestinal nematodes

A

anal itching, slow growth, anaemia

19
Q

Another name for roundworm

A

Ascariasis - may creep out of any orifice

20
Q

Problems caused by roundworm?

A

migration of larvae the most common cause of morbidity
blockage of intestines
migration to other organs

21
Q

Life cycle of roundworm

- learn!

A
produce 20000 eggs/day excreted in feces
mature in soil (3 weeks)
ingested
hatch and penetrate wall
enter lymph/blood
carried to liver, heart, lungs - further development
coughing brings up adult
22
Q

blood and tissue nematodes are called….

23
Q

where are filarie found? - how transmitted?

A

blood and lymph, adults discharge larvae that circulate in the blood.
Ingested by insects where the develop into infective larvae.

24
Q

3 e.g. of blood/tissue nematodes?

A

river-blindness
elephantitis
loiasis (inflammation of skin and eye)

25
Cestodes can live for ....
decades
26
How are cestodes transmitted?
Ingesting a cist in undercooked meat
27
When do cestodes get dangerous?
Ingestion of egg means larval stages will invade tissue (muscle/brain) If they stay in the lumen of the gut symptoms are minor
28
Trematodes live.... and cause damage to...
Live for decades in blood vessels or tissue | progressive organ damage
29
What do trematodes use as an intermediate host?
Snails
30
How do you catch yourself a trematode?
eat infected crab/fish
31
2nd greatest economic impact of a parasitic disease
schistosomiasis (snail fever)
32
How is schistosomiasis transmitted?
contaminated water (eggs excreted in urine or feces)
33
Symptoms of schistosomiasis
swimmers itch | 2 months later: fever, chills, cough, muscle ache
34
How does schistosomiasis damage?
eggs stick to tissue and damage is due to immune response - scarring of tissues, lead to bladder cancer
35
schistosomiasis life-cyle
Free living larvae in water, infect snail In snail the develop swimming tail Penetrate human host Migrate through body - final destination dependent on species (bladder, intestine)
36
How to diagnose nematodes/cestodes?
Feces sample or just coughing/vomming it up
37
How to diagnose schistosomiasis?
Eggs in feces or urine sample.
38
How to diagnose tissue nematode?
Difficult to diagnose adults in tissue | Look at microfilariae in blood