Wednesday 24 November 2004
protozoal infection, protozooses
HPC:295 : nodal toxoplasmosis
Naegleria fowleri amoeba in brain. Small trophozoites, pale nucleus
Parasitic protozoa are single-celled eukaryotes that are major causes of disease and death in developing countries.
Protozoa can replicate intracellularly within a variety of cells (e.g., Plasmodium in red blood cells, Leishmania in macrophages) or extracellularly in the urogenital system, intestine, or blood.
The most prevalent intestinal protozoans, Entamoeba histolytica and Giardia lamblia, have two forms: (1) motile trophozoites that attach to the intestinal epithelial wall and may invade and (2) immobile cysts that are resistant to stomach acids and are infectious when ingested.
Blood-borne protozoa (e.g., Plasmodium, Trypanosoma, and Leishmania) are transmitted by insect vectors, in which they replicate before being passed to new human hosts.
Toxoplasma gondii is acquired either by contact with oocyst-shedding kittens or by eating cyst-ridden, undercooked meat.
- visceral leismaniasis
- cutaneous leismaniasis
- mucocutaneous leismaniasis
- diffuse cutaneous leismaniasis
- african trypanosomiasis
- american trypanosomiasis (Trypanosoma cruzi)