Parasites

Question 1

what are protozoa?

Answer 1

microscopic single- celled eukaryotes

Question 2

what is the active form of a protozoan?

Answer 2

trophozoite

Question 3

what is the inactive stage of a protozoan?

Answer 3

a cyst

Question 4

which stage is infective and resistant?

Answer 4

the cyst stage

Question 5

how are protozoa classified and what are the major types?

Answer 5

based on their organs of locomotion.

amoebas (pseudopods), flagellates , ciliates and sporozoans (no mode of locomotion)

Question 6

what is the important human amoeba pathogen and what cases would other amoeba infections be present?

Answer 6

entamoeba histolytica

when a person has ingested human excriment

Question 7

what are the important human flagellate pathogens?

Answer 7

giardia lambia, trichomonas vaginalis, trypnosoma cruzi (Chagas’ disease) and brucei (sleeping sickness) and leishmania

Question 8

what is the important human cilliate pathogen?

Answer 8

Balantidium coli (rare in US)

Question 9

what is the important human sporozoan pathogen?

Answer 9

plasmodium species that cause malaria

Question 10

what is a helminthe?

Answer 10

a multicellular parasite with organ systems and reproductive structues (generally macroscopic)

Question 11

what is a cestode and which are the most important human pathogens in this group?

Answer 11

a flat worm (tapeworm)

taenia solium, taenia saginata and Diphyllobothrium latum

Question 12

how are T solium and T saginata acquired by humans?

Answer 12

eating underprepared meat

Question 13

what are nematodes and what are the most common infectious members?

Answer 13

round worms

ascaris lumbricoides, anclostoma duodenale, necator americanus, trichuria trichiura and enteroius vermicularis

Question 14

how many species of Plasmodium cause malaria in humans and what are they?

Answer 14

4

P fallciparum, P vivax, P ovale and P malariae

Question 15

how many people die of malaria per year?

Answer 15

one million

Question 16

what are the genetic factors that protect against malaria?

Answer 16

HbS, HbC (both in heterozygous and homozygous states) and people who lack the Duffy factor (resistant to P vivax)

Question 17

why is P vivax not a major concern in Africa and which strain is?

Answer 17

because most people lack the Duffy antigen

P falciparum

Question 18

what do mosquitos infected with malaria inject into humans and where does it immediately travel?

Answer 18

plasmodium sporozites

hepatocytes

Question 19

how long does the malaria liver stage take and what happens afterwards?

Answer 19

it takes 1-2 weeks and then the hepatocyte ruptures

Question 20

what stage of the malaria parasite exits the liver and what does it sub sequentially infect?

Answer 20

the merozoites

red blood cells