Malaria: The Parasite in the Mosquito - Dr. Mramba Nyindo

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来自 Duke University 的课程

Tropical Parasitology: Protozoans, Worms, Vectors and Human Diseases

154 个评分

Duke University

Tropical Parasitology: Protozoans, Worms, Vectors and Human Diseases

154 个评分

This course provides students an understanding of important human parasitic diseases, including their life cycles, vectors of transmission, distribution and epidemiology, pathophysiology and clinical manifestations, treatment, and prevention and control. Tropical Parasitology is taught by faculty from an area highly impacted by tropical parasites- the Kilimanjaro Christian Medical University College in Moshi, Tanzania. The faculty include Drs. Frank Mosha and Mramba Nyindo (and two lecturers, Drs. Johnson Matowo and Jovin Kitau). Dr. John Bartlett, Professor of Medicine, Global Health and Nursing at Duke University, joins his faculty colleagues in this effort.

从本节课中

Protozoans

We are excited to begin our Protozoa cluster, focusing on malaria, trypanosomiasis, toxoplasmosis, and leishmaniasis. Despite advances in prevention and treatment, protozoal diseases contribute substantially to the global burden of morbidity and mortality. This cluster has a total of 153 minutes of video and 85 pages of reading spread out over the four lessons. Each lesson has all of the readings, lectures, and additional materials to help you understand the topic. You will have unlimited opportunities to take an untimed quiz after you’ve mastered the material in each lesson, and you have four quizzes to complete in this cluster. (Note: this cluster includes a case study practice quiz, ungraded, which is optional). This cluster kicks off with a close look at malaria vectors and the fascinating research being done on diagnosing, treating, and vaccinating against malaria. This is by far the largest cluster in the course, so you have up to 3 weeks to complete this cluster.

Malaria: Vectors - Dr. Johnson Matowo4:00

Malaria: Vector Control - Dr. Johnson Matowo6:59

Malaria: Insecticide Resistance and Management - Dr. Johnson Matowo 11:34

Malaria: Epidemiology - Dr. Franklin Mosha8:28

Malaria: Mosquito Breeding Sites - Dr. Franklin Mosha 0:43

Malaria: The Parasite in the Human Body - Dr. Mramba Nyindo11:46

Malaria: Invasion and Colonization of Red Blood Cells by Merozoites - Dr. Mramba Nyindo 6:58

Malaria: The Parasite in the Mosquito - Dr. Mramba Nyindo 7:29

Malaria: Pathophysiology - Dr. John Bartlett7:38

Malaria: Interview with Dr. Venance Maro 4:12

Malaria: Interview with Dr. William Howlett 4:17

与讲师见面

John A. Bartlett, M.D.
Professor of Medicine, Global Health and Nursing at Duke University Medical Center
Duke Global Health Institute
Franklin Mosha, Ph.D.
Professor of Parasitology and Medical Entomology
Mramba Nyindo, Ph.D.
Associate Professor, Kilimanjaro Christian Medical University College (KCMU Co.)

Part III is on malaria parasite in the mosquito.

You have the human, and the mosquito.

So we shall discuss this parasite in the mosquito.

What are the events in the mosquito?

By the process of merogony, malaria parasites will grow and

they become schizonts.

And merozoites.

This is the usual thing with this infection.

You have a schizont, it has merozoites in it.

They will, the infected red blood cell or will bite and

these will look for red blood cell.

Merozoites cause malaria fever.

This process of the life cycle of

these parasite in the mosquito is termed sporogony.

Malaria parasites grow, and they become gametocytes and sporozoites.

How? We shall see it.

Sporozoites in the mosquito saliva will initiate

malaria infection in the humans.

We have jumped a lot of these that happen, before

the mosquito can inject it, infective forms of this parasite.

We repeat ourselves that malaria gametocytes will arise

from very young trophozoites, in the red blood cell, very early sporozoites.

Gametocytogony will take anything from eight days or more.

In malaria, it

is about four days to produce gametocytes.

That is to say, I repeat myself,

gametocytogony may take eight days in

Fewer days in Plasmodium vivax, half of the time to generate gametocytes.

The blood meal containing gametocytes, in the red blood cell,

will initiate the stage development in the mosquito.

In the mosquito gut red blood cells will rupture.

It's a very different environment.

They will rupture,

and the gametocytes will be released from the red blood cell.

And things will start happening as we move on.

These gametocytes, are either macrogametocytes,

which are the female, or the male ones, which are microgametocytes.

The microgametocytes undergoes a very,

very interesting phenomenon we call exflagellation.

It makes flagellates, flagellated organism.

It's very important, these are flagellated organisms.

They look very much like sperm, they will identify macrogametocytes.

Exflagellation will take ten to 15 minutes to complete the process.

Exflagellation will give you eight nucleated flagellated bodies essential for

fertilization of gametocytes.

Exflagellated microgametes will tear free from macrogametocyte,

and move actively toward the macrogametes and invade them.

Let's repeat that exflagellated microgametes tear free from

from macrogametes, they move around, they tear free.

And then they're very active really.

They are to identify a macrogametocyte whom they will invade.

And at that time syngamy takes place for a zygote.

This is immotile, the zygote is immotile,

it elongates to form the ookinete.

The dimensions are given there, 18 micrometer long by 3 to 5 micrometer wide.

This is a very interesting body.

Ookinete is very active.

It will penetrate the mosquito gut.

The idea here is to move forward to the salivary glands of the mosquito.

Where things will happen, an oocyst will be formed.

The ookinete will lodge under the outer limiting membrane of the gut.

Here, a cyst wall develops on the ookinete to form the oocyst.

What comes next is the sporoblast, which are formed from the oocyst.

There is also formation of

chromatin dots that will arrange peripherally to the sporoblast.

Then we come to really interesting, the sporozoites,

which the mosquito injects to a human being to initiate malaria.

These sporozoites will arise or do arise from sporoblasts.

They break loose.

And form an entangled mass of oocyst.

One oocyst may contain 10,000 sporozoites, it's a very lively population.

This make, makes transmission possible.

What happens, sporozoites will invade the mosquito coelom, the body cavity.

Then sporozoites are happy to make their way to the 3-lobed salivary gland.

They assemble about the cells surrounding the salivary glands.

They want to get out from the mosquito to the human being.

Sporozoites will invade the lumen of the ducts of salivary gland.

These are now ready to be inoculated into humans.

When the female mosquito will takes a blood meal.

Inoculated sporozoites travel to the liver, and the life cycle continues.

This marks the end of part III of malaria parasites in the mosquito.

We appreciate your participation.

Thank you, and goodbye.

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