introduction to parasites Flashcards
what is a parasite defined as?
an organism that lives in a host organism and gets its food at the expense of the host
what parasitic disease causes the most deaths globally?
malaria
what 3 classes of parasites are there?
protozoa
helminths (worms)
arthropods
what are some example of protozoa?
malaria
amoebae
flagellates
what are some examples of helminths?
roundworms
tapeworms
flukes
what are some examples of arthropods?
lice
ticks
mites
what are protozoa?
microscopic, one celled organisms that are able to multiply in humans
how are protozoa transmitted?
fecal - oral route if they live in the human intestine
arthropod vector if they live in the blood or tissue of humans
what parasite causes malaria?
plasmodium species
what is the life cycle of malaria?
sporozoites injected under skin by mosquito
travel through blood and enter liver
mature in liver and re-enter circulation as
merozoites
invade red cells, multiply and lyse cells- reinvade more red cells
what parasite causes amoebic dysentry?
entamoeba histolytica
what are some clinical features of amoebic dysentry?
cysts in stool and liver abscess in late disease
what parasite causes leishmaniasis?
leishmania species carried by the sandfly
how is leishmaniasis diagnosed?
histology of the biopsy
what are the 3 major species of schistosomes?
s. haematobium
s. mansoni
s. japonicum
