Parasites

Question 1

What is a parasite?

Answer 1

Organism that lives in another organism

Gets it’s food at the expense of the host

Question 2

What are the 3 classes of parasites?

Answer 2

Protozoa
Helminths
Arthropods

Question 3

Give examples of helminths…

Answer 3

Roundworms
Tapeworms
Flukes

Question 4

Give examples of protozoa…

Answer 4

Malaria (parasite that causes it)
Amoebae
Flagellates

Question 5

Give examples of arthropods…

Answer 5

Lice
Ticks
Mites

Question 6

Name 3 major illnesses caused by protozoa.

Answer 6

Malaria

Amoebic Dysentery

Leishmaniasis

Question 7

How do protozoa tend to be transmitted?

Answer 7

Fecal-oral route or via an arthropod vector

Question 8

What are the symptoms associated with malaria?

Answer 8

Fever
Chills
Other flu-like symptoms

Question 9

Describe the life cycle of malarial parasites…

Answer 9

Sporozoites injected under skin by mosquito

Travel in blood to liver

Mature in liver to merozoites

Re-enter circulation

Invade RBC’s, multiply, lyse, invade more RBC’s

Merozoites produce gametocytes

Gametocytes form taken up by mosquito and sheg: leading to production of sporozoites

Process repeats

Question 10

A patient has got amoebic dysentery. What symptoms/signs are they likely to present?

Answer 10

Diarrhoea with blood/pus

Intestinal and extra-intestinal infections

Possible liver abscess (in late disease)

Question 11

How would you identify amoebic dysentery in a stool sample, under a microscope?

Answer 11

Cysts

2 nuclei + chromatoid body

Question 12

How is leishmaniasis transmitted?

Answer 12

Bites of sandflies

Question 13

What typical symptoms are there of cutaneous/muco-cutaneous leishmaniasis?

Answer 13

Skin/mucosal ulceration

Question 14

What health affects are caused by visceral leishmaniasis?

Answer 14

Fever
Weight loss
Hepato-splenomegaly

Question 15

What is the sellotape test used for?

Answer 15

Pinworm infestation (sellotape shows Ova when looked at under a microscope)

Type of roundworm

Lives up your bum

Question 16

Tapeworms are transmitted through ingestion of beef or pork.

What form are they found as, in these meats?

Answer 16

Cyst

Question 17

What are nematodes?

Answer 17

Round worms

Question 18

What are cestodes?

Answer 18

Tape worms

Question 19

What are trematodes?

Answer 19

Flat worms

Question 20

What thread like, 1cm long hilminth is commonly found in children?

Answer 20

Enterobiasis (pinworm)

Question 21

What are Ova?

Answer 21

Eggs of parasites

mature female reproductive cell

Question 22

Which nematode is responsible for causing Loefller’s syndrome?

Briefly describe what the condition is.

Answer 22

Ascaris lumbricoides

Accumulation of eosinophils in lungs

Question 23

Where do roundworms tend to inhabit when they infect a human?

Answer 23

Small intestine

Ascaris can also live in the common bile duct

Question 24

Taenia saginata and taenia solium are both types of what?

Answer 24

Cestode - tapeworm

Question 25

In the context of tapeworm transmission, describe what an intermediate and definitive host are.

Answer 25

Larval cysts ingested by animal (cow or pig) and then passed to humans when we eat beef/pork Livestock ∴ intermediate host Cyst only matures to adult tapeworm in human Human ∴ definitive host

Question 26

What is cysticercosis?

Answer 26

Parasitic infection of cysts of T.solium Invade the brain, muscles or other tissues

Question 27

What is the other main type of tapeworm, aside from solium and saginata? Describe the main features of infection by this tapeworm.

Answer 27

Eichinococcus Carried by dogs, foxes, wolves Humans ingest eggs which hatch then enter circulation Hydatid cyst forms in liver - must be surgically resected

Question 28

Schistosomiasis (flukes) is an infection caused by what type of helminth?

Answer 28

Trematodes (flatworms)

Question 29

What are the 3 major species of schistosomes, and organs does each affect?

Answer 29

S.haemotobium - bladder S.mansoni - intestines S.japonicum - intestines

Question 30

What is the intermediate host, used by schistosomes?

Answer 30

Snails

Question 31

Describe how schistosomes infect humans.

Answer 31

Ova excreted in urine/faeces near/in fresh water Maricadia (swimming larvae) released into fresh water Penetrate snail body Cercaria emerge from snails after 4 - 6 weeks which penetrate human skin (swimmers itch) Migrate from lungs to liver where they mature to schistosomes then migrate to mesenteric or bladder Lay eggs that cause inflammation of organ wall

Question 32

What fever is caused by schistosomes (bilharzia)?

Answer 32

Katayama fever

Question 33

Which type of schistosome infection is most severe?

Answer 33

S.japonicum

Question 34

Which schistosome is associated with causing haematuria and bladder cancer?

Answer 34

S. haematobium

Question 35

If you suspected that a patient had been infected by a Helminth. What could you test for in the blood, and why?

Answer 35

Eisonophil levels IgE levels Infection if often accompanied by eosinophilia and elevated IgE levels

Question 36

In diagnostics, what 3 things would you look for in a faeces sample, to look for evidence of parasitic infection? PCO

Answer 36

Parasites Cysts Ova

Question 37

How is malaria testes for?

Answer 37

Blood films: thick and thin

Question 38

Summarise how a parasitic infection can be tested for.

Answer 38

Faeces microscopy Serology Thin+thick blood films Tissue microscopy