Parasites

Question 1

What is a parasite? (wide range of pathogens)

Answer 1

• organism that lives in another organism (host) and gets its food at the expense of this host (depends on host for survival)
• simple organism
• More complex than bacteria

Question 2

what disease causes the most deaths globally?

Answer 2

Malaria

Question 3

What are the 3 classifications of parasites?

Answer 3

1. protozoa
2. helminths (worms)
3. arthropods

Question 4

What are some of the main properties of protozoa? (3)

Answer 4

1. microscopic (single celled)
2. can be free living (on its own) or parasitic in nature
3. can multiply in humans

Question 5

What are the 2 ways that protozoa can be transmitted and where is each found?

Answer 5

1. faecal- oral route; lives in human intestine

2. arthropod vector; lives in tissues or blood (blood transfusion)

Question 6

What are some of the main symptoms of malaria?

Answer 6

Flu like symptoms: fever (pyrexia), chills,profuse sweating, nausea, diarrhoea, vomiting, blood in stool, muscle pain

Question 7

What is the parasite species which causes malaria?

Answer 7

Plasmodium falciparum (p. falciparum)

Question 8

What is the mosquito species which spreads malaria?

Answer 8

Anopheles mosquito

Question 9

Which diagnostic technique is used to detect parasiteamia which shows infected red cells?

Answer 9

Giemsa stain (stains thick and thin blood films)

Question 10

When p. falciparum is injected into the skin, what is it called and where do mature and re- enter?

Answer 10

Sporozoites (early stage in the life cycle); mature in the liver and re-enter the circulation

Question 11

What do sporozoites mature into and what do these do?

Answer 11

Merozoites; invade RBCs, multiply and lyse cells. They t re-infect again

Question 12

What form does the parasite have to be in to be taken up by the mosquito?

Answer 12

Sexual form (of the cycle)

Question 13

What are the 2 most common malaria control methods?

Answer 13

1. insecticide treated mosquito nets (ITN)

2. prophylaxis (preventive treatment)

Question 14

What is the name of the parasite which causes dysentery?

Answer 14

entamoeba histolytica (e. histolytica)

Question 15

What are some of the main symptoms of dysentery?

Answer 15

diarrhoea with blood/ pus/ mucus, nausea and vomiting, chills, abdominal pain, pain in passing stool, fatigue

Question 16

What can dysentery lead to in late disease once it becomes intestinal and extra intestinal?

Answer 16

Liver abscesses

Question 17

What is the active/ feeding stage of the entamoeba histolytica parasite called and what does it do?

Answer 17

Trophozoite: it ingests RBCs by throwing out pseudopodia (extension of the cytoplasm)

Question 18

What does cutaneous and muco-cutaneous leishmaniasis mean?

Answer 18

causes skin and mucosal ulceration

Question 19

What are leishmaniasis symptoms?

Answer 19

fever, weight loss, hepato-spleenomegaly (swelling), neuralgia (pain in nerves)

Question 20

What is another name for visceral leishmaniasis?

Answer 20

“flesh eating” disease

Question 21

What are the 3 types of leishmaniasis and what do they effect?

Answer 21

1. cutaneous; affects skin (skin ulceration)
2. sub-cutaneous: affects mucosal membranes
3. visceral: affects internal organs such as spleen and liver (most dangerous and often fatal)

Question 22

How is leishmaniasis diagnosed?

Answer 22

Through biopsy (histological diagnosis)

Question 23

What are the 3 main protozoal infections?

Answer 23

1. malaria
2. dysentery
3. leishmaniasis

Question 24

What are the 3 main protozoa?

Answer 24

1. malaria 2. amoebae 3. flagellates

Question 25

what are the 3 main helminths?

Answer 25

1. roundworm (nermatode) 2. tapeworm (cestode) 3. flat worm (trematode)

Question 26

what are the 3 main arthropods?

Answer 26

1. lice 2. ticks 3. mites

Question 27

What is the name of the pinworm infection? (roundworm)

Answer 27

eneterobiasis vermicularis

Question 28

what is the diagnosis of nematodes?

Answer 28

press adhesive sellotape against the perianal region in the morning (ova also seen in microscopy)

Question 29

What is an example of one of the most common and biggest nematodes?

Answer 29

Ascaris lumbricoides

Question 30

How does ascaris lumbricoides develop?

Answer 30

Ingested eggs hatch in small intestine, larvae carried to the lungs and are swallowed again, adult worms inhabit and develop in small intestine

Question 31

What can obstruction of the small intestine or common bile duct by ascaris lumbricoides cause?

Answer 31

jaundice

Question 32

Is ascaris lumbricoides symptomatic? (roundworm)

Answer 32

Usually asymptomatic but can have transient/short pulmonary symptoms (Loefller's syndrome)

Question 33

What are the two examples of a tapeworm (cestode) found in their intermediate hosts, beef and pork?

Answer 33

Taenia saginata- found in beef | Taenia solium- found in pork

Question 34

What do tapeworms taenia saginata and taenia solium cause?

Answer 34

Tissue cysts in infected humans (definitive hosts)

Question 35

What is the example of the most common tapeworm (cestode) which is carried by dogs and animals generally?

Answer 35

Echinococcus species

Question 36

What does echinococcus (tapeworm) cause in the liver?

Answer 36

Hydatid cyst (contains watery fluid and tapeworm)

Question 37

If a hydatid cyst was accidentally punctured, what would this cause?

Answer 37

Aphylaxis (severe allergic reaction which can be fatal)

Question 38

What is an example of the most common fluke (caused by a flat worm?

Answer 38

Schistosomiasis

Question 39

What are the 3 main schistosomiasis species?

Answer 39

1. S. haematobium (bladder) 2. S. mansoni (intestinal) 3. S. japonicum (intestinal)- MOST DANGREROUS

Question 40

What do miracidia (free swimming schistosomiasis stage) use as their intermediate host?

Answer 40

Snails

Question 41

What happens to cercaria once they penetrate human skin? (where do they move to?)

Answer 41

Liver and lungs, then once matured move to mesenteric and bladder venules

Question 42

What does schistosomiasis lead to?

Answer 42

Katayama fever

Question 43

What does schistosoma haematobium cause?

Answer 43

- haematuria (blood in urine) | - bladder cancer

Question 44

What are the main diagnostic techniques for identifying parasites?

Answer 44

- blood films (for malaria: thick and thin films) | - serology: detection of antibodies when parasites present in deep tissue sites

Question 45

What two factors indicate a helminth infection (worm infection)

Answer 45

- elevated IgE | - eosinophilia

Question 46

What 3 microscopy stages can be present in parasitology?

Answer 46

- parasite - cysts - ova