protozoans Flashcards
what is the lifecycle of plasmodium falciparum in mosquitos
mosquito takes blood meal of infected individual, picking up gametocytes of the parasite (both macrogametocytes and microgametocytes)
mosquito’s internal environment triggers changes in gametocyte
—- in the stomach, microgametocyte (male) undergoes exflagellation, when the sperm comes out of the microgametocyte
the sperm fertilizes the macrogametocyte (still in the stomach) – now we have the diploid zygote
the zygote changes, it’s DNA replicates to become tetraploid and motile – now called an ookinete
the ookinete moves thru the epithelial layer of the stomach into the stomach’s walls, resting against the hemolymph
the ookinete will become an oocyst (haploid itself) and undergo sporogony, an asexual reproductive process of spore (haploids) formation —- creates a thousand of sporozoites
—- the cyst will rupture and the sporozoites will enter the hemolymph
the sporozoites will travel and enter the mosquito’s other organs
—- one being the salivary glands, it will then traverse thru the epithelial cells into the duct
now it can be injected into another host when a mosquito gets a blood meal
differentiate between marcogametocytes and microgameteocytes
macro - female “egg”
micro - male “sperm”
of the parasite
what is the lifecycle of plasmodium falciparum in humans
sporozoite injected into humans during a mosquito’s blood meal via its saliva
sporozoites enter the bloodstream until they find somewhere to hide from the immune system
—- the only cells they can enter at the hepatocytes in the liver
once sporozoites inside the cell, they become a cryptozoite (no longer infective)
—- in the liver, it undergoes schizogony, asexual reproduction by multiple fissions (no cytokinesis until it fills the hepatocyte and the cell will rupture and then the cryptozoites undergo cytokinesis)
——— schizonts is what the mass of cells are before the division aka cytokinesis
the cryptozoites are released into the bloodstream, now called a merozoite (after having left the liver) – the merozoite cannot go back and reinfect the liver
the merozoites infect red blood cells
erythrocytic cycle (occurs over and over again)
—- in the red blood cell, the merozoite changes its morphology into rings. the ‘signet’ ring form is the early version of the trophozoite form and is what infects the red blood cells – and then later, the trophozoite
—- changes the way the red blood cell looks, expressing its own proteins – some of the proteins are stick which causes the red blood cell to stick to the endothelium —- causing blockages in the vascular
—- the trophozoites will asexually divide thru schizogony – the red blood cell will rupture, releasing the merozoites into circulation
—- later on a small portion become gametocytes
another mosquito will come and take a blood meal, taking in the merozoites and gametocytes
—– merozoites have no effect on mosquitos (don’t propagate but they do affect humans)
—– gametocytes are what propagates the plasmodium falciparum
what issues does plasmodium falciparum cause in humans?
anemia – breaks down our red blood cells
vascular issues – blockages because red blood cells stick to endothelium c
where does the term malaria originate from?
medieval italian
mala aria = bad air
originally thought to come from inhaling bad air (not true)
it’s actually passed from one human to another by the bite of an infected mosquito
which demographic is more vulnerable to malaria?
children
haven’t developed immunity
what causes malaria?
plasmodium parasites
describe the plasmodium phylum
apicomplexa (they glide)
obligate parasites (always require a host for reproduction and survival)
they require 2 different hosts
—- vertebrate host for live/blood stages (INTERMEDIATE)
—- arthropod vector for sexual reproduction (DEFINITIVE/FINAL HOST)
more than 100 species of plasmodium
what are the species of plasmodium that have been recognized to infect humans? describe them
plasmodium falciparum
—- causes the most death
—- widely distributed in tropical areas and very prevalent in africa
—- cycle of 48 hours (spike in fever every 48 hours)
plasmodium virax
—- found mainly in asia and latin ameria
—- similar in how it functions to ovale
—- cycle of 48 hours
plasmodium ovale
—- found in mainly west africa
—- similar in how it functions to virax
—- cycle of 48 hours
plasmodium malariae
—- typically causes chronic infection
—- cycle of 72 hours
plasmodium knowlesi
—- zoonotic malaria in humans (from macaques)
—- cycle of 24 hours (shorter!)
what is the arthropod vector for human malaria?
female anopheles mosquitos when they get their blood meal (for reproduction)
males only eat sugar, but females have sugar and blood meals
note, only 30-40 out of 430 anopheles species can actually transmit malaria
what role does the proboscis play in mosquitos
pierces the skin; used to take blood meals from humans
what is hemolymph?
circulatory fluid in invertebrates
found in open circulatory systems
what role does the salivary glands play in mosquitos?
holds the merozoites and gametocytes to be injected into humans
initially saliva is used to numb humans and thin out the blood to prevent clotting in mosquitos
what role does the stomach play in in mosquitos?
storage area for blood meal
what role does the crop play in mosquitos?
storage area for sugar meal
