Welcome to this presentation on Human African Trypanosomiasis. Commonly knows as Sleeping Sickness. This presentation has been prepared by Mramba Nyindo and Yovani Tao. My name is Mramba Nyindo at the Kilimanjaro Christian Medical University College, Moshi, Tanzania. We have two parts of this presentation, part 1 is on distribution, the tsetse fly, forms of the parasite etc. Sleeping sickness occurs in two geographical areas in Africa. It occurs in East Africa. Causes East African sleeping sickness. It also cause in West Africa, where is causes West African sleeping sickness. They, these two diseases clinically are very different and you'll see later. This is a map showing you the distribution of the East African sleeping sickness. Compared it to a larger distribution of the West African sleeping sickness on this African continent. Tsetse flies are vectors of sleeping sickness. These flies belong to the genus Glossina, and this genus Glossina consists of 21 species. Note that tsetse flies are found only in Africa, and they occurred south of the Sahara-Somalia deserts and to the north of Namibia and Kalahari deserts. There are 3 groups of tsetse flies in Reverine, also known as Palpalis. These, tsetse flies are associate with the rivers and lakes and there are many big rivers and also lakes in Africa. Nine species have been identified here. I'll give you an example of Glossina palpalis and Glossina. gambiensis, Glossina palpalis palpalis, and Glossina gambiensis, and Glossina tachinoides. The second one is Savannah or Morsitans group. These will occu, these occupy a very large area of the African continent. The Sava, Savannah grasslands and bushlands. These are important transmitters of nagana, which is Trypanosomiasisof animals. Examples of this tsetse flies are Glossina morsitans morsitans, Glossina pallidipes, and glossina orientalis. The third is the Fusca or forest group and this is found in the great lakes of west and west Central Africa. And they are, they are really big lakes and forest. Examples are Glossina fusca fusca, Glossina logipennis, and Glossina nashi. This is a table showing you there's species for riverine, species for savannah, and species for forest tsetse groups. Let's look at the reproduction [SOUND] of tsetse flies. Note that females flies are mated only once as teneral flies. One insemination. The ovaries produce one egg at a time. This is, this is fertilized in the uterus by sperm stored in the spermatheca of the female tsetse fly. Eggs hatch in the uterus and transform to first instar larva. This transforms it to the second and third instar larva. The third instar larva is extruded at partuition, tsetse flies give birth. Larva is deposited at a convenient place where it pupates. The puparium molts twice to produce a pupa. Followed by an adult in about a month or more days later. The female tsetse flies produce 8 to 12 larvae in her life time. Examples here are given of a Glossina palpalis. Glosinna mortisans no to the pro boshis which is almost a hypodermic, hypodermic, hypodermic needle. This is the one which will be inserted into your skin for the uptake of blood meal by tsetse fly. What about the organism? This sleeping sickness is caused by a single-celled organism in the Order Kinetoplastida genus Trypanosoma. Where do they live in blood? They are plasma parasites and they live in blood. However, occasionally, these parasites will invade the brain and spinal cord and cause very serious manifestations. Let's look at the morphology of these parasites, trypanosomes. They are lanceolate in shape, the posterior end is slighty blunted. the anterior end is pointed. They measure anything from 15 to 30 micrometer by 15 to 5 micrometer. They multiply by binary fission. They split themselves into two parts. This is, a demonstration here of what we find in black. This parasite type here is known as the long and slender. This is termed the intermediate, and this one is actually a stumpy form. This moves here to become a stumpy form. These three morphological forms are important to be realized is in the blood. Because it is only this form which has a mitochondria that is able to leave and divide in the [tsetse guide. The parent species or brucei species is known as Trypanosoma brucei brucei, or sensu stricto. This is a parasite of wild and domesticated animals, it's not a human parasite. There are three morphological identical trypanosomes. Brucei rhodesiense, berucei gambiense, and brucei brucei. Three morphologically identical trypanosomes are known. Then, how do we differentiate the 3 brucei sub-roles. Clinically, the course and severity of infection is important. Trypanosoma brucei rhodesiense will cause the acute sleeping sickness disease. Trypanosoma brucei gambiense will cause the chronic disease. Trypanosoma brucei brucei cause nagana in animals. As I said, is not a human parasite. A high density lipoprotein factor in human serum lyses trypanosoma brucei. brucei, brucei of animals. Therefore these parasites can not grow in human body. How but this test has problems because it does not seem to be 100% effective. We can go further to differentiate these parasites by identification of zymodemes. Ultimately PCR is, the final way of differentiating these parasite types. Trypanosoma brucei rhodesiense occurs in east and southern Africa. We've seen in the beginning of this presentation the map. The parasite causes acute sleeping sickness and when not treated fast, the patient will die. However, gambiense, Trypanosoma brucei gambiense, which occurs in central and west Africa. Causes the chronic disease, chronic sleeping sickness. Protracted illness takes long for the patient to die. Let's look what a very important structure of this parasites known, known as the surface coat, which is a survival factor of these parasites in blood. The surface coat consist of a compact mass of glycoprotein. 15 to, 10 to 15 nanometer thick. It is, lying on the plasma membrane. It lies there. It is deposited on the plasma membrane. [COUGH] The surface coat. Embraces the whole organism. The whole parasite. To which including the surface area of the flagellar pocket. The surface coat is responsible for antigenic variation of the African trypanosomiasis. The parasite periodically substitutes the amino acids on the surface coat. Thereby, it camouflages itself from immunological attack by phenomenon popularly antigenic variation. Therefore, sleeping sickness becomes chronic infection. There is no way that you can eliminate these parasites from your blood. Because they go on changing, joint changing. Keeping up with any immunological attack that you can monitor. These are two pictures here, electromicrographs. Parasite in blood, parasite in tsetse gut. Look at this surface coat. Very thick area on the plasma membrane. This is the flagellum pocket. This is a parasite in the tsetse gut. Just plasma membrane here. With a lot mitochondria which are not found here. These are my own preparations made some years back. This is, becomes the end of Part One. On human African sleeping sickness. Thank you so much for your participation. We shall talk on Part Two a little bit later.
