Trypanosomiasis: Interview with Dr. William Howlett

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From the course by Duke University

Tropical Parasitology: Protozoans, Worms, Vectors and Human Diseases

158 ratings

Duke University

Tropical Parasitology: Protozoans, Worms, Vectors and Human Diseases

158 ratings

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.

From the lesson

Protozoans

Trypanosomiasis: Vectors/Epidemiology/Control - Dr. Franklin Mosha11:55

Trypanosomiasis: Sleeping Sickness - Dr. Mramba Nyindo11:19

Trypanosomiasis: Human African Trypanosomiasis - Dr. Mramba Nyindo7:48

Trypanosomiasis: Pathophysiology - Dr. John Bartlett6:30

Trypanosomiasis: Interview with Dr. Venance Maro 4:57

Trypanosomiasis: Interview with Dr. William Howlett 7:16

Meet the Instructors

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.)

So the, the, the the disease that you asked me to

say a few words about is Trypanosomiasis, or sleeping sickness.

And Trypanosomiasis is a,

it's a protozoan, what we call they are kind of not as big as,

as, as helminths and not as small as, as bacteria or fungi.

But, and of course they often have an intermediate host, or

a vector I should say, that carries them.

In this case it's carried by the tsetse fly.

And what is, what is you know,

what is we're in an endemic area for trypanosomiasis here in, in East Africa,

more particularly in Northern Tanzania, because we're near the game parks.

And so

the tsetse flies are the, are the vectors and

the hosts are the, the ungulates, or the animals, the ones with hooves.

And of course that would mean all the antelopes and

some of the, some of the cows.

And of course, humans become accidentally infected if they happen to

be bitten by the tsetse fly.

And they're carrying the protozoa that normally would be propagated

by tsetse fly to, to to the four, four legged animal like an,

like an antelope or a, or a, or a maybe cows for example, cattle.

Now there're a couple of interesting points about it.

One is the disease was, was, was responsible for hundreds of

thousands of deaths in epidemics in the, in the, the last century.

Early in the last century, particularly in, in Uganda.

And that's, that's when it, it rose to prominence.

And if I explain to you that all of the national parks that you

see now are what we call areas that are not inhabited by humans.

And the reason that they're not inhabited is not because the land isn't good.

In actual fact the land is excellent.

But if they went to live there, they died.

They died of sleeping sickness.

Because their animals got bitten by tsetses' who, who,

who carried the protozoa.

And of course the animals died and then the humans died with them.

So, and that is the actual, the logistics of the game parks in East Africa.

So it's, it's paradoxical that that's why they exist.

And now, the disease

of course is a big public health disease, and it's divided up into two types.

East, East African and West African.

And at the moment West Africa is much more common.

And there also it's, it's tsetse fly but it's a different trypanosome.

One is, is, is rhodesiense, and the other is gambiense.

Rhodesiense is East African and gambiense is West African.

And the, clinically the diseases are slightly different.

Now I don't want to go into that today,

but both will give rise to a chronic, febrile disease.

The East African is more virulent and kills you more quickly.

Both will kill you, unless you kill it.

Like all protozoa, or I'll select many protozoa.

You, you, like falciparum malaria is, is the same.

You get a bad infection, you have to kill the, the parasite or it will kill you.

But with sleeping sickness, you, you have to, to, to kill it.

Now, and medically that is very difficult to do, because the drugs we

have are the same drugs as we've used for the last half century or the last century.

There's no impetus to create a new drug for a disease that is very focal.

We estimate there are about 50,000 probably deaths a year

in Africa due to it.

A big epicenter now would be in the Democratic, Democratic Republic of Congo

because of the political instability, then public health measures to, to,

to, to decrease human, human transmission of the disease would have decreased.

How would you prevent it?

Well you can try to get decreased tsetse fly.

That's almost impossible.

But you can actually decrease their breeding habitat near rivers.

They're, they're, they're specific.

The flies actually breed in an, in a,

in an area, a couple of hundred meters near, near wet areas.

That's their ecosystem.

And they're tropic for moving animals, and

that's why when you're sitting in your, in your Land Rover,

the tsetse flies will actually go to the Land Rover when it moves.

So that when you,

immediately when you're moving you'll see them accumulating outside the window,

pull down the windows and they'll come in.

And they fly fairly fast at about 30 kilometers an hour.

So they would, and they give you a very nasty bite.

The disease, it is difficult to recognize clinically unless you are experienced in

terms of the clinical presentation, or

what the organism looks like under a microscope.

And that's why it's much feared.

And of course, and there're only a few specialized centers in,

in high-income countries that carry the medications that are used for it.

So it's not an easy disease.

It's quite uncommon now in East Africa.

We used to see on average maybe four or five cases a year,

up to about say five years ago and now the number has decreased.

I haven't seen a case of trypanosomiasis myself clinically for

the last four of five years.

But it does exist and we're aware of it's, of it's and it's a threat.

And it can occur in epidemics, especially when there is a breakdown in the in what

we call, in, in a war like situation as we have our civil, civil disturbance.

I have emphasized that East Africa is only comprised of about 5% of the total burden

of the disease, and West Africa 95% and places like Uganda have both types.

And It's a, it's considered an exotic disease, but killed hundreds of thousands

at the turn of the century, particularly in Uganda, and was much feared.

Much feared.

It had the same, it's the same connotation as yellow fever in West Africa, and

Malaria in West Africa.

They were traditionally called white man's grave.

sleeping sickness was a, was a cause of great fear.

And of course you can imagine that if it kept the game parks free of people,

it must have been pretty, pretty extensive disease.

So WHO are very aware of it, and there are increases and

decreases over time, and tanzania reports about 100 cases per year.

Most of them coming from the western part of Tanzania or by the lake, lake areas.

So, rather than Eastern Tanzania where we have the high,

where we have the game parks.

So, it is extremely low within our game parks.

And I don't want the the tourist board coming after me saying that we,

we have a lot of escaping sickness in our, in our big Serengetis' and

Lake Manyaras' and Tarangire National Park.

It does exist and we have to be aware of it.

And thank you.

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