Parasitology Flashcards
treatment for amebic (amebiasis) and flagellated (giardiasis, trichomoniasis) diseases
PO nitroimidazoles: metronidazole, tinidazole
nitroimidazoles MOA
nitroaryl compounds – reduce to nitro radical anions– react with O2–superoxide radical anions– reduced to H2O2– OH radical. considered reactive oxygen species and are implicated in damage to the parasite
treatment for intestinal nematodes (roundworm)
PO benzimidazoles: mebendazole, albendazole
benzimidazole MOA
bind to tubulin protein, preventing its polymerization to form the cytoskeleton of eukaryotes
treatment for blood nematodes (roundworm)
PO semisynthetic macrolide: ivermectin
ivermectin MOA
selectively/strongly binds to glutamate-gated chloride ion channels in invertebrate nerve/muscle cells– increase permeability of cell membrane to chloride– hyperpolarization– paralysis/death
treatment for cestodes (tapeworm)
PO isoquinolone derivative: praziquantal
praziquantal MOA
in human intestinal lumen: Ca redistribution in worm, leading to muscle contraction and paralysis. in blood: damages worm tegument, resulting in attack by human antibodies
what are the 4 protozoa
amoebae, flagellates, ciliates, sporozoa
defining characteristic of amoebae
“ameboid” appearance meaning it changes shape
defining characteristic of flagellates
have one or more whiplike flagella (flagellatus=whip)
defining characteristic of sporozoa
complex life cycle with alternating sexual and asexual reproductive phases
what are the 3 helminths
nematodes, cestodes, trematodes
nematodes are
roundworms
cestodes are
tapeworms
trematodes are
flatworms/flukes
defining characteristic of nematodes
large size, cylindrical form, unsegmented bodies
defining characteristics of cestodes
25-50 ft length, flat, ribbonlike. head is 4 muscular, cup-shaped sucking disks, crown of hooklets
what is an individual segment of a cestode called
proglottid
what is a chain of proglottids called
strobila
defining characteristics of trematodes
flat, fleshy, leaf-shaped/football-shaped worms with 2 muscular suckers
important note for life cycle of trematodes?
require intermediate hosts to complete their life cycle which are most commonly mollusks (snails, clams)
important note for life cycle of cestodes?
definitive hosts are humans. intermediate hosts harbor larval forms. if humans become intermediate hosts then death is possible and great damage.
where are parasites more likely to be, geographically
tropics and subtropics
what info can you find about parasites at cdc.gov
life cycles, epidemiology, pathogenesis, prophylaxis, therapy
what are some nomenclature clues
location (geographic), individual, source or vector, sign or symptom
parasite modes of transmission
most commonly ingestion of contaminated food or water, insect bite, direct contact thru skin. respiratory droplet transmission is very uncommon
why do you think we named protozoa meaning “first animal”
they are unicellular eukaryotes, display characteristics associated with animals: motility, heterotrophy
what does heterotrophy mean
organisms incapable of food production, are food producers
describe very generally the protozoan life cycle
cyst and trophozoite cycle.
what type of personality is a cyst
SURVIVOR: vegetative, nonmotile, quiescent, resistant, infective
what type of personality is a trophozoite
DESTROYER: active, motile, feeding
how do amoebae replicate
binary fission (splitting the trophozoite), development of numerous trophozoites within the mature multinucleated cyst
how do amoebae move
pseudopodia (false foot): protoplasmic flow, via extension of the pseudopod, extrusion of ectoplasm, and snail like movement
when does the cyst form develop
drop of temperature or humidity
respiration of amoebae?
facultative anaerobe
how do amoebae get their nutrition
pinocytosis, phagocytosis
what kind of relationship do amoebae have with their host
commensal/symbiotic relationship: one species benefits, other is neither harmed nor helped
describe the general life cycle of helminths?
egg–> larvae–> adult male and adult female (cycle)
how are nematode infections of the intestinal tract confirmed
identification of characteristic eggs in the feces
how are blood roundworms characterized
they are infections transmitted by biting insects such as mosquitoes or flies. they produce filariae
what are the larval forms of blood roundwarms called
microfilariae
reproductive organs of cestodes?
hermaphroditic: male and female organs are present in each mature proglottid
defining characteristics of cestode eggs
nonoperculated, contain hexacanth (6 hooked) embryo
how do cestodes get nutrition?
lack a digestive system so absorb food from host intestine through the soft body wall of the worm
the naming of a disease follows this: _____ “iasis”
genus-iasis
cysts are associated with __
protozoa
eggs are associated with ___
helminths
proglottid and strobila are associated with ____
cestodes
malaria is associated with ____
sporozoa
filariae are associated with ____
nematodes
the larval form of blood roundworms are called ____
microfilariae
trichomoniasis is associated with _____
flagellates
