Tsetse Fly and Trypanosomes Overview

Tsetse Fly and Trypanosomes

• Tsetse flies transmit trypanosomes, a type of parasite.
• The parasites infect mammals.
• The life cycle involves metacyclic trypomastigotes injected into the mammalian host.
• These transform into bloodstream trypomastigotes, carried to other sites (lymph, spinal fluid).
• Replication occurs by binary fission.
• The parasite infects the tsetse fly by taking a blood meal.
• In the fly's midgut, parasites become procyclic trypomastigotes, multiply, and transform into epimastigotes.
• Epimastigotes multiply in the fly's salivary glands.
• The cycle in the fly takes about 3 weeks.
• Humans are the main reservoir for Trypanosoma brucei gambiense, though wild game animals are the primary reservoir for T. b. rhodesiense.

Sarcodina (Amoebozoa)

• Sarcodina are protozoans with a protoplasmic membrane and no defined shape.
• Pseudopodia are used for locomotion and feeding.
• They can be free-living (like Amoeba), commensal (Entamoeba coli), or parasitic (Entamoeba histolytica).

Amoeba proteus

• Amoeba proteus lives in well-oxygenated fresh water.
• It's found on decaying vegetation in pools, ponds, and streams.
• Water regulation occurs via contractile vacuoles.
• Amoeba moves and feeds using pseudopodia.
• Its movement is known as amoeboid movement.
  • It involves changes in the protoplasm (from a sol state to a gel state).

Feeding in Amoeba

• Bacteria are engulfed by pseudopodia.
• This creates a food vacuole (phagosome).
• The food vacuole fuses with lysosomes, forming a phagolysosome.
• Digestion occurs within the phagolysosome, and nutrients absorbed.
• Waste products are expelled from the cell.

Parasitic Amoebae (Class Archamoeba)

• Six genera of parasitic amoebae are known, five are in the intestinal tract, one in the buccal cavity.
• Entamoeba coli is a commensal found in the intestines.
• Entamoeba histolytica causes amoebic dysentery; a parasitic amoeba in the intestines.
• Entamoeba gingivalis is a commensal found in the buccal cavity.

Comparison between Entamoeba histolytica and E. coli

Plasmodium (Phylum Apicomplexa)

• Plasmodium is an intracellular parasite.
• It causes malaria in humans and other mammals.
• Transmitted by bloodsucking arthropods (intermediate hosts).
• Four species cause malaria: P. vivax, P. malariae, P. ovale, P. falciparum.
• Malaria is caused by parasites of Plasmodium.

Plasmodium Life Cycle

• The life cycle involves an erythrocytic cycle in the liver and blood, and a mosquito cycle (sexual reproduction).
• Gametocytes are sexual stages in the host
• The exerythrocytic cycle occurs in the liver.
• The erythrocytic cycle occurs in human red blood cells.
• A mosquito bite releases sporozoites into the bloodstream for the next cycle.

This quiz explores the relationship between tsetse flies and the trypanosomes they transmit. It covers the life cycle of these parasites, their impact on mammals, and the classification of related protozoans like Sarcodina. Test your knowledge on these fascinating organisms!