Parasites Flashcards
what are protozoa?
microscopic single- celled eukaryotes
what is the active form of a protozoan?
trophozoite
what is the inactive stage of a protozoan?
a cyst
which stage is infective and resistant?
the cyst stage
how are protozoa classified and what are the major types?
based on their organs of locomotion.
amoebas (pseudopods), flagellates , ciliates and sporozoans (no mode of locomotion)
what is the important human amoeba pathogen and what cases would other amoeba infections be present?
entamoeba histolytica
when a person has ingested human excriment
what are the important human flagellate pathogens?
giardia lambia, trichomonas vaginalis, trypnosoma cruzi (Chagas’ disease) and brucei (sleeping sickness) and leishmania
what is the important human cilliate pathogen?
Balantidium coli (rare in US)
what is the important human sporozoan pathogen?
plasmodium species that cause malaria
what is a helminthe?
a multicellular parasite with organ systems and reproductive structues (generally macroscopic)
what is a cestode and which are the most important human pathogens in this group?
a flat worm (tapeworm)
taenia solium, taenia saginata and Diphyllobothrium latum
how are T solium and T saginata acquired by humans?
eating underprepared meat
what are nematodes and what are the most common infectious members?
round worms
ascaris lumbricoides, anclostoma duodenale, necator americanus, trichuria trichiura and enteroius vermicularis
how many species of Plasmodium cause malaria in humans and what are they?
4
P fallciparum, P vivax, P ovale and P malariae
how many people die of malaria per year?
one million
what are the genetic factors that protect against malaria?
HbS, HbC (both in heterozygous and homozygous states) and people who lack the Duffy factor (resistant to P vivax)
why is P vivax not a major concern in Africa and which strain is?
because most people lack the Duffy antigen
P falciparum
what do mosquitos infected with malaria inject into humans and where does it immediately travel?
plasmodium sporozites
hepatocytes
how long does the malaria liver stage take and what happens afterwards?
it takes 1-2 weeks and then the hepatocyte ruptures
what stage of the malaria parasite exits the liver and what does it sub sequentially infect?
the merozoites
red blood cells
