An Introduction to Parasites

Question 1

What is a parasite?

Answer 1

An organism that lives in another organism (host) and gets its food at the expense of the host

Question 2

How does the complexity of parasites compare to bacteria?

Answer 2

They are simple organisms but more complex than bacteria

Question 3

What do parasites cause?

Answer 3

Many diseases with malaria causing the most deaths globally

Question 4

What are the 3 classes of parasites?

Answer 4

Protozoa

Helminths (worms)

Arthropods

Question 5

What are examples of protozoa?

Answer 5

Malaria

Amoebae

Flagellate

Leishmaniasis

Question 6

How is malaria spread?

Answer 6

By mosquito

Question 7

What are symptoms of amoebae?

Answer 7

Diarrhoea with blood/pus and cysts formed in stool

Question 8

What does leishmaniasis cause?

Answer 8

Skin or mucosal ulceration

Leads to fever and weight loss

Question 9

How does leishmaniasis spread?

Answer 9

Bite by sandflies

Question 10

How is leishmaniasis diagnoses?

Answer 10

Histology of biopsy material

Question 11

What are examples of helminths?

Answer 11

Roundworms (nematodes)

Tapeworms (cestodes)

Flukes (trematodes)

Question 12

What is the scientific name of roundworms?

Answer 12

Nematodes

Question 13

How are nematodes diagnosed?

Answer 13

Pressing adhesive tape againt perianal region in the morning

Question 14

Where are nematodes ova seen?

Answer 14

In microscopy

Question 15

How are nematodes transmitted?

Answer 15

Faecal-oral route

Question 16

What is a common nematode and what does it do?

Answer 16

Ascaris lumbricoides which is a mass of worms that may obstruct the intestine or bile duct

Question 17

What are common cestodes?

Answer 17

Taenia saginata (beef)

Taenia solium (pork)

Question 18

How do cestodes spread?

Answer 18

Larvae cysts ingested in meat

Question 19

Where are cestodes ova seen?

Answer 19

In stool

Question 20

What is a species of cestodes carried by dogs and transmitted by humans ingesting eggs?

Answer 20

Echinococcus spp

Question 21

What is the scientific name of flukes?

Answer 21

Tramatodes

Question 22

What is the scientific name of tapeworms?

Answer 22

Cestodes

Question 23

What are common kinds of trematodes?

Answer 23

Schistosomes species:

S.haematobium (bladder)

S.mansoni (intestinal)

S.japonicum (intestinal)

Question 24

Where are high rates of trematodes found?

Answer 24

Near fresh water

Question 25

What is an important thing in the life cycle of trematodes?

Answer 25

Snails

Question 26

What are examples of arthropods?

Answer 26

Lice Ticks Mites

Question 27

What are protozoa?

Answer 27

Microscopic once celled organisms that can be free living or parasitic in nature

Question 28

How are protozoa transmitted?

Answer 28

Faecal-oral route (live in human intestine) Arthropod vector (live in blood or tissue)

Question 29

Where do protozoa that are transmitted by the faecal-oral route live?

Answer 29

Human intestine

Question 30

Where do protozoa that are trasmitted by a arthropod vector live?

Answer 30

Blood or tissue

Question 31

What is the life cycle of malaria?

Answer 31

1) Sprozoites injected under skin by mosquito 2) Travels through blood and enters liver 3) Matures in liver and re-enters circulation at merozoites 4) Invade red cells, multiply and lyse cells

Question 32

What is the life cycle of schistosomiasis?

Answer 32

1) Miracidia released in fresh water 2) Penetrate body of snail 3) Cercaria emerge from snail after 4-6 weeks 4) Penetrate human skin 5) Travel from lungs to liver 6) Mature in liver into worms (schistosomes) that migrate to the bladder venules 7) Lay eggs that cause inflammation

Question 33

When does a definitive diagnosis of a parasite happen?

Answer 33

Once the parasite is identified in host tissue or excreta

Question 34

What are the different stages present in microscopy?

Answer 34

Parasites Cysts Ova

Question 35

What is rarely possible for parasites?

Answer 35

Culture

Question 36

What is used to diagnose malaria?

Answer 36

Blood films

Question 37

What is serology?

Answer 37

Detection of antibodies

Question 38

Is serology used to detect parasites?

Answer 38

Yes it can be useful, especially for parasites in deep tissue