Eukaryotic Parasites 2

Question 1

What are the 3 major types of helminths?

Answer 1

roundworms, tapeworms and flukes

Question 2

Why is the life cycle of helminths different to other parasites?

Answer 2

Because they develop their eggs outside of humans - in another animal, or in soil or in a plant

Question 3

What is the exception to this?

Answer 3

strongyloides - can complete sexual reproduction in human host

Question 4

What are nematodes?

Answer 4

roundworms

Question 5

What are enterobius vermicularis?

Answer 5

pinworms - highly contagious roundworms that live in the lower colon and rectum

Question 6

What is the life cycle of pinworms?

Answer 6

Female pinworms crawl out of the anus at night and lay eggs - the eggs are ingested by humans and the larvae hatch in the small intestine and become adults and mate in the caecum

Question 7

What is pinworm infection uncommon in adults?

Answer 7

better hygiene

Question 8

How long will pinworms live for if they can’t reinfect?

Answer 8

4-6 weeks

Question 9

What is the treatment for pinworms?

Answer 9

antihelminthic

Question 10

What is ascaris lumbricoides?

Answer 10

a large intestinal roundworm

Question 11

What does ascaris lumbricoides cause?

Answer 11

GI obstruction, respiratory obstruction, cholecystitis, pancreatitis, pneumonitis - but mainly asymptomatic

Question 12

What is the lifecycle of ascaris?

Answer 12

Eggs are laid in the jejunum and then go into the faeces which will contaminate soil, eggs will mature in subtropical or tropical soil and then will reinfect humans via a contaminated water supply or plants - the larva hatch in the small intestine and then migrate through hepatic circulation to the lungs - in the lungs they go into alveolar spaces and then go back up the trachea to be swallowed

Question 13

What is the treatment for ascaris?

Answer 13

antihelminthics

Question 14

What is strongyloides?

Answer 14

a roundworm that can cause infection by skin penetration

Question 15

Why is strongyloides a risk factor for gram negative sepsis in immunosupressed patients?

Answer 15

because immunosupression will cause dissemination and bring with it gram negative organisms

Question 16

Why is strongyloides different from other helminths?

Answer 16

Because auto infection can happen - can happen decades after leaving an endemic area

Question 17

What is the life cycle of strongyloides?

Answer 17

larvae in the intestine are excreted into the stool, develop into free living worm adults, produce eggs, eggs hatch infective larvae and penetrate the skin. Or the larvae can remain in the intestine and penetrate intestinal mucosa - self infection.

Question 18

How are stongyloides treated?

Answer 18

antihelminthic

Question 19

What is schistosoma mansoni?

Answer 19

A fluke that causes bilharzia

Question 20

Where does schistisoma live?

Answer 20

mucosal associated veins - GIT or urinary

Question 21

How does schistisoma infect?

Answer 21

it is transmitted by fresh water snails and penetrates the skin when swimming

Question 22

What is the distribution of schistisoma?

Answer 22

africa, tropical south america, carribean - need an area with fresh water snail and human contact

Question 23

What are the symptoms of a schistisoma infection?

Answer 23

in an acute infection only an itch and non specific febrile, if a chronic infection - hepatomegaly, splenomegaly, collateral circulation, portal hypertension, pulmonary fibrosis

Question 24

What is the treatment of schistisoma?

Answer 24

antihelminthic

Question 25

What is one way of controlling schistisoma infections?

Answer 25

snail control with molluscacides

Question 26

What is the life cycle of schistisoma?

Answer 26

penetrates skin, travels through blood to the liver, enters portal venous system, matures in portal veins, migrates to venules of large bowel, lays eggs in blood stream and gut lumen, eggs passed out through faeces, returns to water supplies, hatch in water, penetrate fresh water snails

Question 27

What is the general effect of all tapeworms?

Answer 27

They consume nutrients - causes most of their impact

Question 28

What is echinococcus granulosus?

Answer 28

tapeworms where humans are accidental intermediate hosts

Question 29

What does echinococcus cause?

Answer 29

hyatid cysts in the liver and lungs

Question 30

How is echinoccous transmitted?

Answer 30

With sheep or goat contact in rural areas

Question 31

What is the definitive host of echinococcus?

Answer 31

dogs

Question 32

What happens if a cyst from echinococcus bursts?

Answer 32

It causes a very immunogenic anaphylactoid reaction

Question 33

How is echinococcus treated?

Answer 33

pre treat with an antihelminthic agent or ‘puncture aspiration injection resaspiration’ to reduce the size of the cyst before removal with surgery

Question 34

What is taeniasis?

Answer 34

cestode parasites causing neurocysticercosis (cysts in the brain)

Question 35

What kind of hosts are humans for taeniasis?

Answer 35

either definitive or intermediate (not necessary hosts)

Question 36

What are the symptoms of taeniasis infection?

Answer 36

may be asymptomatic or may cause epileptic foci

Question 37

How do you commonly get a taeniasis infection?

Answer 37

eating undercooked meat - meats that aren’t under controls are more of a risk

Question 38

How is taeniasis treated?

Answer 38

with antihelminthics - but won’t treat unless necessary as treatment may cause an immune response

Question 39

What is the distribution of taenia solium?

Answer 39

africa, latin america, asia