Last week I explain the malaria parasite’s life cycle involves two hosts and includes two cycles with various stages.
Recap: the first cycle includes a pregnant mosquito of the genus Anopheles passing sporozoites (through it’s saliva) into an (in this case) human host.
Question: I don’t clearly understand what comes first, the infectious mosquito or the diseased human the mosquito bites?
In a human, the plasmodium parasite, in the form of sporozoites, enters blood vessels, making their way to the liver and multiply in hepatocytes (liver cells), eventually bursting the cell ↓, to exit as merozoites.
Enter merozoites ↓ into red blood cells where parasite continues to develop in stages↓.
1 Red blood cell (RBC)
2 Ring Stage
3 Trophozoite Stage – Greek, Trophē, food or nourishment and zōon, animal.
4 Schizont Stage – G, schizoto, split or cleave + ōn (ont-), a being.
5 Merozoite – G. mēros, share + zōon, animal.
(note: ↑ the RBC bursts releasing more merozoites in the bloodstream and infect more red blood cells)
6 Gametocytes (Sexual development) G. gametēs, husband or gametē, wife + kytos, cell (some merozoites develop into gametocytes (sexual form of parasite).
Meanwhile, a new mosquito arrives to feed upon the infected host, and while enjoying a blood meal, ingests gametocytes. In the stomach of this mosquito, microgametes (male) penetrate macrogametes (female) producing a zygote.
And the sporogonic cycle continues.
Come on…what a process and aren’t these great words! There’s more! ↓
1 Gametes – Greek gametēs, husband; gametē, wife
and Zygote G. zygōtos, yoked
2 Ookinete (midgut) – G. ōon – egg + kinētos, motile.
3 Oocyst (grows and bursts) G. ōon – egg + kystis, sac.
4 Sporozoite (released in mosquitos salivary glands) G. sporo,– the sewing of a seed + zōon, animal.
Eventually the mosquito makes its way to another human host only to perpetuate the malaria cycle.
Malaria comes from the Italian mal aria which translates to bad air. It was thought that malaria was caused by noxious air coming from the marshlands. Something was coming out of those marshlands but it was not the air that caused malaria, it was a mobile bug, inside the mosquitoes, that laid their eggs in the wetlands.
I am intimidated at the start of this particular study. With Alejandro’s help, I figure things out. Once I get going, the cycle unravels as I move from one stage to the next…etc.
I feel a sense of respect for this parasite. I only nick the information but feel like I could do a whole detailed series of large works on this one bug alone – there is so much more wonder to it. #cyclesandstages #stageandcycles
I ask Alejandro for one more bit of information to share with me.
Monica, to be honest, I have been working on Plasmodium for over 10 years and I still find myself discovering new things about it that fascinate me.
Mmmm…What about: this parasite has been affecting humans for so long and so strongly, that it’s considered the most powerful force for recent selection of human genetic variations. Meaning that people with variations in their DNA that confer resistance to this disease are selected, even if that has some side-effects (like sickle-cell or alpha-talassemia).
Otra ves, gracias Alejandro!
more → Alejandro Marin Menéndez
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