Here is a compilation of term papers on ‘Trypanosoma’. Find paragraphs, long and short term papers on ‘Trypanosoma’ especially written for college and medical students.
Term Paper on Trypanosoma
Term Paper Contents:
- Term Paper on the Habits and Habitat of Trypanosoma
- Term Paper on the Morphology of Trypanosoma
- Term Paper on the Physiology of Trypanosoma
- Term Paper on the Life Cycle of Trypanosoma
- Term Paper on the Pathogenicity of Trypanosoma
- Term Paper on the Prevention of Trypanosoma
- Term Paper on the Treatment (Therapy) of Trypanosoma
Term Paper # 1. Habits and Habitat of Trypanosoma:
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The genus Trypansoma is parasitic in the blood of most of the vertebrates such as fishes, amphibians, reptiles, birds and mammals. Many species of Trypanosoma are pathogenic causing human disease called trypanosomiasis. Only three species of its are pathogenic in man, viz., T. gambiense, T. rhodesiense and T. cruzi, T. gambiense and T. rhodesiense cause a fatal disease in human beings (hosts) called sleeping sickness in Africa, while T. cruzi causes chagas disease in children of South America. Their transmission from one vertebrate host to other takes place by invertebrate blood-sucking animals such as insects and leeches. These animals are called vectors.
T. gambiense also lives harmlessly in the blood of the African antelopes. Besides, it also parasitizes monkeys, pigs, buffaloes, dogs and other wild, domestic and smaller laboratory mammals. These hosts are only temporary or reservoir hosts in which the parasite does not grow and multiply but simply waits for suitable chance for transmission to the human host. It has no noticeable effect on these hosts but causes fatal diseases in man and his domestic animals.
Term Paper # 2. Morphology of Trypanosoma:
i. Shape and Size:
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T. gambiense is a unicellular, microscopic, slender, elongated, colourless, leaf-like protozoan. Its body measures about 10 μm to 40 μm in length and 1 µm to 5 µm in breadth. The anterior end of body is pointed and the posterior end is blunt.
ii. Pellicle:
The body is covered by tough but elastic pellicle which is composed of numerous microtubules.
iii. Cytoplasm:
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Pellicle is followed by cytoplasm which is differentiated into an outer clear layer called ectoplasm and an inner granular endoplasm. The endoplasm contains single nucleus, single mitochondrion, single Golgi apparatus, endoplasmic reticulum and ribosomes. It lacks contractile vacuole and food vacuoles, however, contains many scattered greenish refractile bodies, called volutin granules. These granules contain glycogen and phosphates and represent reserve food material of Trypanosoma.
iv. Nucleus:
Nucleus is single, oval vesicular and is located in the middle of its body. It contains a large endosome, karysome or nucleolus. As nucleus is concerned with the nutritive functions of the parasite, it is often called trophonucleus. Mitochondrion is single, elongated, giant and extents from animal’s anterior to the posterior end of the body. It is called chondriome. A conspicuous mass of DNA, called kinetoplast, is embedded in the mitochondrion just near the gullet.
A small pocket-like depression on one side near the posterior end represents gullet and reservoir.
v. Flagellum:
Trypanosoma being monoflagellate contains single long flagellum which originates from a basal body which is located lose close to the gullet near posterior end of body. It consists of an axoneme comprising microtubules in 9 + 2 arrangement and bounded by the plasma membrane.
Flagellum extends forward along the body to project beyond its front end, in the form of free flagellum. All along its length over the body, it is connected to the body by a fin-like undulating membrane formed of cytoplasm and folded pellicle. Undulating membrane is supposed to be an adaptive structure for locomotion in a viscous environment (blood, lymph) where it lives.
vi. Blepharoplast:
The flagellum has its origin in a minute basal body or blepharoplast, lying just below the reservoir at the posterior end of the body. It is deeply stained although it is hardly visible in a living specimen. It corresponds to the centriole of a metazoan cell and controls the locomotor apparatus.
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vii. Kinetoplast:
The parabasal body or kinetoplast is a comparatively larger rod-shaped body found near the blepharoplast. It is readily seen in a stained specimen. The kinetoplast shows the presence of DNA. In the region of the kinetoplast the mitochondrial tube dilates into a flattened disc to surround the DNA, the fibres of which run antero-posteriorly within the disc.
viii. Undulating Membrane:
When the flagellum beats, the pellicle attached to it is drawn out into a membranous fold. This fold bordered by the attached flagellum is known as the undulating membrane. It is lateral, thin, irregular, fin-like or crest-like and thrown into numerous graceful ripples in some species. The undulating membrane is said to be an adaptation to movement in a viscous medium (blood).
Polymorphism in Trypanosoma:
Trypanosoma is a polymorphic from; it occurs in following four morphological forms:
i. Amastigote Form or Leishmanial Stage:
It is represented by rounded form which is without any external flagellum as in the genus Leishmania. It is a rounded or oval form in which reduced flagellum remain in the cytoplasm; basal body and kinetoplast are situated in the anterior part of body.
ii. Promastigote Form or Leptomonad Stage:
It is represented by an elongated form with the kinetoplast lying to the anterior to the nucleus (antenuclear kinetoplast). The flagellum arises near kinetoplast and emerges from the anterior end of body, as in the genus Leptomonas and others. In it, the flagellum is short, unattached and free.
iii. Epimastigote Form or Crithidial Stage:
It is represented by an elongated form with the kinetoplast lying anterior and close to the nucleus (i.e., juxtanuclear kinetoplast); the flagellum arising near it emerges from the side of the body to run along a short undulating membrane.
iv. Trypomastigote Form or Trypanosome Stage:
It is represented by an elongated form with post-nuclear kinetoplast situated at the posterior end of the body. The flagellum arises near the kinetoplast and emerges from side of body to run along an undulating membrane, as in genus Trypanosoma.
Out of these four forms trypomastigote is the adult stage while other forms represent developmental stages which are formed during the part of its cycle in the invertebrate host.
Term Paper # 3. Physiology of Trypanosoma:
1. Locomotion:
Locomotion in Trypanosoma is possible by the vibratile movements of undulating membrane and flagellum. The whole body also produces waves for locomotion.
2. Nutrition:
Trypanosoma feeds by absorbing nutrients (mainly glucose) from the blood of host by diffusion through pellicle (called osmotrophy). Pinocytosis also occurs in the region of gullet. Since there is not phagocytosis, so food vacuoles are absent in Trypanosoma.
3. Respiration:
Respiration in Trypanosoma is aerobic; gaseous exchange occurs by diffusion through the pellicle. Glucose metabolism is found intimately related with growth and development of mitochondrion. Initially, absorbed glucose undergoes glycolysis (anaerobic process) to release energy.
At this stage, the mitochondria of the parasite are without cristae and are inactive. When the host produces antibodies, against the parasite, it stops glucose absorption. The mitochondria of the parasite, develops cristae and becomes active. The mitochondrion produces enzymes needed for the Krebs cycle. These enzymes oxidize pyruvic acid (which is produced during glycolysis) and as a result carbon dioxide, water and energy are produced. At this stage, parasite does not reproduce.
4. Excretion:
The nitrogenous waste materials are ammonia and organic acids. These are eliminated by diffusion through the pellicle over the entire surface of body.
5. Osmoregulation:
The cytoplasm of Trypanosoma’s cellular body is isotonic with the blood plasma. So little fluid is absorbed by animal’s body and there is no consequent problem of osmoregulation. Due to this reason, the contractile vacuole is absent in Trypanosoma.
Reproduction:
Reproduction in trypanosomes takes place by the longitudinal binary fission. This is the only method of reproduction, which is found in all the stages of the life-history. During binary fission, the basal body (blepharoplast) divides first, then subsequently the kinetoplast and nucleus and finally the cytoplasm. Usually one daughter individual retains the old flagellum and undulating membrane, and the other daughter develops a new one which grows out before the complete separation on the daughter.
Term Paper # 4. Life Cycle of Trypanosoma:
T. gambiens is a digentic pathogen; it passes its life cycle in two different types of hosts:
1. Primary host or definitive host in which parasite lives initially in blood outside the red blood cell (i.e., extracellularly). Later on parasite live in cerebrospinal host e.g., human beings.
2. Secondary host or intermediate host in which polymorphic forms of the parasite are developed, e.g., blood sucking insect, tsetse fly, Glossina palpalis and Glossina tachinoides. Since tsetse fly carries the trypanosomes from man to man, it is known as vector or carrier. Both male and female tsetse fly bites in daylight, usually in the early morning and evening.
Life Cycle in Human Beings:
Infective stage of Trypanosoma exists in the salivary glands of tsetse fly and is called meta-cyclic form. When such infected fly bites a human being to such the blood, it punctures the skin with its proboscis. It injects its saliva in the wound of human being to check blood clotting (the saliva of tsetse fly contains as anticoagulant).
The infective stage of Trypanosoma enters human blood along with saliva. On reaching the blood of man, the meta-cyclic forms change into long slender flagellated forms. These swim actively by beating their flagellum and multiply asexually by longitudinal binary fission. During this phase of life cycle, parasites absorb glucose from blood of the host and get energy by anaerobic oxidation of food (glycolysis). Up to this stage, the mitochondrion of each parasite has not developed cristae.
Gradually blood of human beings develops antibodies against the multiplying slender forms of Trypanosoma. Due to antibodies, slender forms stop absorbing glucose and their glycolysis too stops. The slender forms also stop their multiplication and change into short stumpy forms, each of which lacks free flagellum.
The stumpy forms get their energy from aerobic oxidation of pyruvic acid which is the end product of glycolysis. Their mitochondria develop cristae and produces enzymes of Krebs cycle. The stumpy are sucked by the tsetse fly along with blood meal. It not sucked they die within 24 hours.
Life Cycle in Tsetse Fly:
When the blood of an infected person is sucked up by a male or female tsetse fly, short and stumpy forms of Trypanosoma enter its alimentary canal along with the blood. These exist in an unchanged form in the midgut for few hours.
Development in Midgut:
After tenth to fifteenth day short-stumpy forms develop into long slender forms. These forms pass into extra-peritrophic space (a space between the peritrophic membrane and the epithelial cells). The slender forms multiply by longitudinal binary fission. By fifteenth day they enter the lumen of the proventriculus.
Development in Salivary Glands:
The long slender forms then migrate forward to the buccal cavity. They pass on the hypopharynx and eventually reach the salivary glands through the opening of salivary ducts. Here they multiply and change their morphology first into crithidial stage and then into meta-cyclic, stage which are infective to man.
Reservoirs:
Trypanosomes are harmless to their natural vertebrate hosts which are wild antelopes. These wild antelopes are not harmed by the parasite; hence they act as reservoir hosts from which infection is spread by the vectors.
Disease:
The bite of an infected fly is usually followed a itching and irritation near the wound, and frequently a local dark red lesion develops. After a few days, fever and headache develop; reoccurring at regular intervals accompanied by increasing weakness and enlarged glands. Usually, however the parasites ultimately succeed in penetrating the cerebrospinal fluid of the brain and spinal cord and sleeping sickness results. In sleeping sickness patient losses consciousness and finally passes into a state of coma ending in death.
Term Paper # 5. Pathogenicity of Trypanosoma:
African sleeping sickness results in general physical and mental depression. Victim constantly sleeps and walks very slowly. Afterwards man loses consciousness and neglects to swallow his food. Later on, trembling of hands and other parts of the body develops with muscular convulsions. Finally, state of total coma results, which leads to death. African sleeping sickness is found only in some parts of tropical Africa, where tsetse flies are found.
Term Paper # 6. Prevention of Trypanosoma:
Direct attacks on the vector of sleeping sickness, tsetse fly, help in checking the spread of sleeping sickness.
These include:
1. Elimination of breeding grounds of tsetse fly.
2. Human population from endemic areas may be isolated.
3. Contact of human population with tsetse fly should be avoided as much as possible.
4. A single intramuscular injection of 4 mg/kg. of Pentamidine remains effective for about 6 months against the disease.
5. Trypanosomiasis can be reduced or prevented by killing the vector (tsetse fly). It involves use of insecticides, such as DDT. The vector can also be eradicated by destruction of its habitat. Bushes and low trees along the rivers in endemic areas should also be cleared.
6. Domestic and wild mammals, which act as the reservoir host, may be put to wholesale destruction to avoid blood-meal of the fly. But it seems impracticable at present.
Term Paper # 7. Treatment (Therapy) of Trypanosoma:
The sleeping sickness can be treated only in the early stages of infection, since once the parasite has entered the cerebrospinal fluid. It is difficult to cure sleeping sickness. Compounds of arsenic (tryparasamide, melarson oxide, melarsoprol and trimelarsen) and antimony were used until recently to cure sleeping sickness (now these drugs are used for final stages of infection).
Two drugs, Bayer 205 (also called Antrypol, Germanin or Suramin) and Pentamidine (or Lomidine) are now widely used for both treatment and prophylaxis of human infections of Trypanosoma. Periodic injections of Naphuride can save a person from catching infection. Various pathogenic species of Trypanosoma.