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Filariasis: Introduction - Dr. Franklin Mosha

Course video 49 of 63

The Nematodes cluster focuses on filariasis, ascariasis, hookworm, and strongyloidiasis. Nematode infestations may impact up to 185 million people in recent estimates of the global burden of disease. This cluster has a total of 90 minutes of video and 8 pages of reading spread out over four lessons. 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 for this cluster. This cluster kicks off by examining lymphatic filariasis and the fundamental need for compassion as a core value in global health practice.

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.

Skills You'll Learn

Disease Control, Disease Biology, Parasitology, Microbiology

Taught By

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

Transcript

Yeah, the topic, filariasis, will be presented in three parts.

We shall start with introduction, and then lymphatic filariasis.

And then lastly, onchocerciasis.

Let's look at the history.

Lymphatic filariasis, has been known for the past 4,000 years.

The first record of filariasis, was made by Samhita of Susruta, in the sixth

century BC, who speculated that filariasis was transmitted by mosquitos.

But, of course, the mode of transmission which he postulated was quite different.

He put forth a theory, that mosquitos would acquire

the would lay eggs in water.

And by drinking that water then people would get infected.

This continued to be believed for quite a long time.

Until 1876, when Bancroft discovered adult form of the in human.

This was followed by Manson, who afters several

years of study was able to demonstrate the lifecycle,

indicating that mosquitoes were involved.

And that hydroceles and elephantiasis,

which initial were believed to be due to unknown

reasons, were attributed to filariasis.

1926, Robies, finally described

the development, and the transmission of onchocerciasis in blackflies.

And this was followed by oblong lifecycles of insects.

[INAUDIBLE] said that Manson is the one who was able to demonstrate that,

to ensure that there was an connection between insects and

human parasitic diseases.

How about filariasis, this is a friction by parasitic nematodes,

which involves vertebrate definitive host, and

arthropod vectors as intermediate hosts.

Characteristic feature of the parasite is the microfilaria larvae,

which is common to all these species here.

The main parasitic species are the vectors,

include wuchereria bacrofti, which is transmitted by mosquito species,

brugia malayi by mosquitos, onchocerca volvulus

transmitted by simulium species, loa loa by chrysops,

mansonelle species by culicoides species, and dracunculus medinesis by copepods.

This is a rough sketch of the lifecycle of the filarial parasite.

We starting from the period of ingestion here, where by the vector,

we normally check the microfilaria during blood feeding.

The microfilaria would enter the gut, from where then would penetrate

the gut of peritrophic membrane, to enter the thoracic muscles.

After going through a process of metamorphosis,

which you will change in form, they will then become the first stage larvae,

which as you can see looks like a sausage.

So this is sometimes called the sausage stage.

This ultimately morphs, into second larva stage, and

finally into third larva stage, which is also the infective stage.

During the next biting period, this is passed to the human,

through the wound, caused by the biting.

In this case, the microfilaria, the infective stage,

crawls and enter the body through the wound.

And once in the human body then, then it goes through a maturation for

about a year, which involves two months.

The others, finally settle, depending on the species,

for.

That settle in the lymphatics.

When in case of they settle in the cutaneous tissue.

Settle in the cavities,

the cavities from the sites.

Then after some time, these two mate, this is the female and this the male.

The male is usually half the size of the female.

These will then mate.

And, the female adult, then, will produce eggs, which will develop in the uterus.

And from that they leave that as microfilaria, which will then

enter the bloodstream, and again ready for

uptake by the diptera host.

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