Trypanosoma brucei gambiense and rhodesiense: Life cycle, Structure and Characteristics

Photo of Trypanosoma brucei gambiense and rhodesiense: Life cycle, Structure and Characteristics

Trypanosoma causes two types of diseases that are commonly known as Trypanosomiasis; there is African Trypanosomiasis and American Trypanosomiasis that are both caused by Trypanosoma parasites but from different species. Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense cause African trypanosomiasis in Humans (it is also named sleeping sickness) whereas Trypanosoma cruzi causes Chagas disease or American Trypanosomiasis in humans. Trypanosoma species are together called Trypanosomes.

What is Trypanosoma?

The genus Trypanosoma is gotten from two words trypanon which means borer and soma which means body. The parasite belongs to the family Trypanosomatidae (and subphylum Kinetoplasta). A common characteristic of members of this family is that different stages or forms of the parasites develop in vectors and vertebrates during their life cycle.

Developmental forms of Trypanosoma species

  1. Trypomastigote this has a flagellum
  2. Epimastigote has flagellum
  3. Promastigote has flagellum
  4. Amastigote form (which is the rounded form that does not have flagella)

Trypanosoma Epidemiology

Trypanosoma gambiense occurs majorly in West Africa and Central Africa while Trypanosoma rhodesiense is predominately distributed in eastern and southeastern Africa. Trypanosoma cruzi occurs in Central and South America.

Trypanosoma Transmission

Transmission of Trypanosoma parasites occurs by bites of tsetse flies (of the genus Glossina) for T. gambiense and T. rhodesiense; the reservoirs for these parasites may include Antelopes (with other wild animals), domestic animals such as cattle as well as humans. Transmission of Trypanosoma cruzi occurs through the feces of bloodsucking reduviid bugs.

Trypanosoma Species

  1. Trypanosoma brucei gambiense
  2. Trypanosoma brucei rhodesiense
  3. Trypanosoma cruzi
Diagram of labeled Trypanosoma parasite (Structure of a Trypomastigote)
Diagram of labeled Trypanosoma parasite (Structure of a Trypomastigote)

 

Trypanosoma Characteristics

  1. Trypomastigote form of trypanosoma has a central nucleus and an elongated mitochondrion containing the kinetoplast in its posterior section.
  2. It has a flagellum which helps it in movement
  3. There are special organelles of the kinetoplastids which include the membrane-enclosed glycosomes (containing the glycolytic enzymes).
  4. In the epimastigote and promastigote forms, the kinetoplast and base of the flagellum are located near the nucleus or more toward the anterior end.
  5. The flagellum of the amastigote form when viewed with an electron microscope has a reduced flagellum

Life cycle of Trypanosoma

  1. The life cycle of trypanosoma parasite starts in the tsetse fly with ingestion of trypomastigotes in a blood meal from humans or any reservoir host. The life cycle in the tsetse takes 3 weeks.
  2. The trypomastigotes then multiply in the gut of the tsetse fly and then migrate to the salivary glands
  3. In the Salivary glands, they transform into epimastigotes and multiply further to form metacyclic trypomastigotes
  4. Whenever the tsetse fly feeds again, the metacyclic trypomastigotes are transmitted by the tsetse fly bite to another host.
  5. In the host, the injected parasites then enter the bloodstream, differentiate into blood-form trypomastigotes and multiply, thereby completing the cycle.

Laboratory Diagnosis of Trypanosoma parasite

  1. Identification of trypanosomes in blood smear of Lymph node aspirate or in the cerebrospinal fluid
  2. Culture and mouse inoculation tests (especially for Trypanosoma rhodesiense)
  3. Antibody tests such as the card agglutination trypanosomiasis test (CATT) are very effective especially in epidemiological surveys.

Trypanosoma symptoms

Symptoms of infection with trypanosoma parasites have been discussed in the individual diseases African Trypanosomiasis. Please refer to it.

Trypanosoma infection Prevention

  1. Wear protective clothing
  2. Use of insecticides to kill insects
  3. Use of netting on windows

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