Holmes Parasite Review

Question 1

Define parasite.

Answer 1

an organism which lives upon or within another living organism at whose expense it obtains some advantage.

Question 2

Which parasite causes the most death worldwide every year?

Answer 2

Malaria

Question 3

What is the definitive host?

Answer 3

The host in which sexual reproduction occurs

Question 4

What is the intermediate host?

Answer 4

The host in which sexual reproduction does not occur

Question 5

T or F: Most protozoan parasites can replicate in humans.

Answer 5

TRUE

Question 6

T or F: Most worm parasites can replicate in humans.

Answer 6

False. Most develop but do not replicate in humans

Question 7

What is tropism?

Answer 7

The ability of parasites ot infect specific tissues

Question 8

What is essential for preventing and understanding parasitic diseases?

Answer 8

Understanding the parasite life cycle

Question 9

What are some mechanisms parasites have to evade the host immune system?

Answer 9

Encapsulation, intraluminal location, immunosuppression, acquisition of host antigens

Question 10

T or F: Drugs that work on parasites often target bacteria and viruses.

Answer 10

False.

Question 11

What are the two main classes of human parasites?

Answer 11

worms and protozoa

Question 12

Where are most schistosomes found?

Answer 12

Africa, SA, some equatorial Asia

Question 13

T or F: The morphology of the parasite is much more important in making a diagnosis than in bacterial infections.

Answer 13

TRUE

Question 14

Describe the lifecycle of the schistosome.

Answer 14

Asexual reproduction in snail, swimming cercariae released into water which can burrow into skin, enter human circulation (lose tail), migrate to blood vessels and grow up, sexually reproduce, release eggs into circulation, eggs find ways into feces

Question 15

What is most of the schistosome toxicity associated with?

Answer 15

Immune response to schistosome eggs, which can result in liver scarring

Question 16

T or F: Humans are the intermediate host of schistosomes.

Answer 16

False. Definitive host

Question 17

What is cercarial invasion?

Answer 17

Dermatitis 2-3 days after skin invasion

Question 18

What are the short term complications of schistosomiasis?

Answer 18

Acute Schistosomiasis (Katayama fever) - A serum-sickness illness with lymphadenopathy and hepatosplenomegaly 4-8 weeks after skin invasion

Question 19

What is the major cell type see to expand in parasite infection?

Answer 19

Eosinophils

Question 20

List some control strategies for schistosomes. (5)

Answer 20

1.) Avoid contact with infected water 2.) Construct wells and latrines 3.) Mass treat populations 4.) Kill the snails 5.) Ongoing research on tests, vaccines, and drugs

Question 21

Describe the location of malaria.

Answer 21

Southern hemisphere africa, asia, middle east, south america.

Question 22

What is the intermediate host for malaria (plasmodium)?

Answer 22

Mosquito

Question 23

Which species of plasmodium cause the most severe disease?

Answer 23

P. falciparum

Question 24

Describe the life cycle of malaria parasites.

Answer 24

Human injected with sporozoites by a female mosquito, Sporozoites become merozoites in the liver and infect RBCs, merozoites become gametocytes which reproduce to gametes and can then be picked up by mosquito again.

Question 25

What are some of the symptoms of malaria?

Answer 25

Anemia, splenomegaly, nephritis, DIC, tissue hypoxia due to microvasculature damage (leading to multiple organ system effects)

Question 26

Why does P. falciparum cause such severe disease?

Answer 26

Cause membrane protuberances on RBCs which damage microvasculature, cause RBCs to stick together and to blood vessels

Question 27

T or F: Acquired immunity prevents high level disease and prevents reinfection.

Answer 27

False. Can get reinfection.

Question 28

T or F: There are malaria vaccines available.

Answer 28

FALSE

Question 29

What type of RBCs to P. falciparum preferentially infect?

Answer 29

Young RBCs, but can infect cells of all ages.

Question 30

Which genetic diseases increase resistance to Falciparum malaria?

Answer 30

Sickle cell disease, G6PD deficiency, thalassemia, ovalocytosis