Learn about the comparison between Trypanosoma Brucei and Trypanosoma Cruzi.
Comparison # Trypanosoma Brucei:
1. Trypanosoma Brucei is a causative agent of African sleeping sickness.
2. Trypanosoma Brucei is found in Tropical Western Africa.
3. Definitive host of Trypanosoma Brucei is man and other vertebrates. In them it is essentially a parasite of connective tissue, i.e., blood and lymph where it multiplies readily. Finally it localises in the brain. Intermediate hosts are several species of fly belonging to the genus Glossina, where they are found in the gut.
4. Trypanosoma Brucei occurs in the vertebrate host as Trypomastigote form. Trypomastigotes show polymorphism. Individual parasites vary in size and shape in the different phases of their existence.
Two main forms are recognised:
(i) Short, thick and stumpy forms:
These measure 10 µ long by 5 µ. broad and without or with a short free flagellum.
(ii) Long, slender forms:
These measure 20 µ long by 3 µ broad and possess long free flagellum.
In general, T. brucei is an elongated spindle-shaped organism. The nucleus is large and centrally located. Kinetoplast is small and is situated at the posterior. The flagellum starts from the posterior end and runs beyond the anterior end as free flagellum. The undulating membrane is thrown into 3 to 4 folds.
5. Trypanosoma Brucei passes its life cycle in two hosts:
(i) Development in vertebrate hosts:
Metacyclic stage of Trypomastigotes introduced by the bite of Glossina (infected) develop into long and slender forms. At the site of inoculation they multiply by longitudinal binary fission and transform into stumpy forms to invade the blood stream.
(ii) Development in Glossina (Tsetse):
The short stumpy forms are ingested by the fly. In the gut of the fly the stumpy forms change to long slender forms and start multiplying for some days. After 15 days they enter the proventriculus and thence to salivary gland via the buccal cavity. Here they again multiply and transform to epimastigote and then again to metacyclic, i.e., short and stumpy forms of trypomastigote.
Comparison # Trypanosoma Cruzi:
1. Trypanosoma Cruzi is causative agent of South American sleeping sickness or Chagas’ disease.
2. Trypanosoma Cruzi is found in Central and South America.
3. Definitive host of Trypanosoma Cruzi is man and other vertebrates. Resides in the muscular and nervous tissues and also in the Reticulo-endothelial system as amastigote forms. Mastigote forms appear in the peripheral blood at times. Intermediate host is reduvid bug like Triatoma.
4. Two main morphological forms of Trypanosoma Cruzi are encountered in the human host.
(i) Trypomastigote form:
It measures 20 µ long by 6µ broad. The nucleus is centrally located. Kinetoplast is large, oval and located posteriorly.
(ii) Amastigote form:
These are round and oval bodies and are 2-4 µ in diameter. Multi-plication of the parasites occurs at this stage only. Trypoastigote forms change to amastigote forms and the change is reversible.
5. Trypanosoma Cruzi passes its life cycle in two hosts:
1. Development in vertebrate hosts—Man becomes infected either by the faecal matter of the bug being rubbed into the wound caused by bug bite or by contamination.
The metacyclic trypomastigotes invade tissue cells and transform into Amastigote form. The amastigote forms multiply by binary fission and after passing through pro- and epimastigote stage become transformed into trypomastigote forms to be liberated in the blood stream.
2. The trypomastigote forms enter the stomach of the bug during the act of biting. In the stomach of the bug they transform into amastigote form and multiply by binary fission. The amastigote forms transform into epimastigote form and multiply again by longitudinal binary fission. After 8-10 days they transform into Trypomastigote form and are excreted with the faeces of the bug.