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Introduction to malaria

Published on October 31, 2010 Archived on December 28, 2016   36 min

A selection of talks on Infectious Diseases

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0:00
This is going to be an introduction to malaria and just to what it is, where it occurs, and why it's there.
0:09
Malaria is caused by Plasmodium, which is a member of the Apicomplexa. Apicomplexa are characterized by having one or more invasive stages, which can enter a cell, where the organism multiplies. Then they have an arrangement for burrowing into cells. The actual invasive stage is able to move along surfaces and actually get into a cell and live inside it.
0:41
Transmission of malaria parasites is indirect via the definitive host, which is a vector mosquito. The reservoir for transmission is man, the intermediate host, and so this is an anthroponosis. This is except for Plasmodium knowlesi, which has been shown recently to be fairly widespread in Borneo for instance, which is malaria acquired from a monkey reservoir, obviously through a mosquito, but this is actually a zoonosis— not very widespread at the moment. Plasmodium has an asexual and sexual life cycle and is mainly haploid. The asexual stages of schizogony in the liver of the human are seen after the bite of a mosquito. Merozoites from actively growing and dividing liver schizonts invade red cells to give dividing schizonts in a continuous erythrocytic cycle. Dormant liver hypnozoites are present in Plasmodium vivax and Plasmodium ovale. They are responsible for relapses. The immature sexual stages in the blood are ingested in the blood-meal by the female mosquito and they mature into male and female gametes in the mosquito's stomach. And then the sporogonic cycle—sporogony starts by the syngamy— that's the fusion of the gametes in the mosquito-- meiosis, and multiple divisions of the zygote to give infective sporozoites, which infect the liver of the next human.

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