What is the first organ or tissue attacked by the malarial sporozoites when they enter the human host from the bite of a mosquit
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1 answer:
Answer:
The malaria life cycle starts when a mosquito carrying the malaria parasite bites a human, injecting the parasite (in its sporozoite form) in its saliva into the human bloodstream.
Once injected into the blood, the sporozoites head straight to the liver and within 30 minutes they have invaded the liver cells. Here they develop from sporozoites into merozoites and multiply rapidly to produce thousands of merozoites. They are usually in the liver cells for 10 days.
In some malaria species, such as Plasmodium vivax and Plasmodium ovale, the malaria parasites can lie dormant? for months or years in the liver. This dormant form, the hypnozoite, can then become reactivated and continue its life cycle causing disease. This dormant stage does not happen in Plasmodium falciparum.
The merozoites burst out of the liver and invade red blood cells? in the bloodstream. Here, they multiply further.
After 48 hours, the merozoites have multiplied so much that the red blood cells burst, releasing more merozoites into the bloodstream, which can then infect more red blood cells.
Over 10 days some merozoites will develop into gametocytes. This is the sexual form of the parasite.
When another mosquito sucks up blood from an infected human they take up the gametocytes.
Once inside the mosquito gut, the gametocytes mature into gametes?.
Male and female gametes fuse together during sexual reproduction resulting in the formation of a mobile ookinete.
The ookinete burrows through the mosquito’s stomach wall.
The ookinete then forms an oocyst on the other side of the stomach wall. Within this oocyst a thousand new sporozoites form.
After about 5-7 days the oocyst bursts, releasing the sporozoites. These then migrate up to the mosquito’s salivary gland, ready to be injected into the next individual it bites.
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