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protozoan infections

Wednesday 24 November 2004

protozoal infection, protozooses


Digital cases

- HPC:295 : nodal toxoplasmosis


- Naegleria fowleri amoeba in brain. Small trophozoites, pale nucleus


- protozoan infection

See also

- infectious agents


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.

Trichomonas vaginalis are flagellated protozoal parasites that are sexually transmitted and can colonize the vagina and male urethra.

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.


- malaria (Plasmodium)
- babesiosis (Babesia microti)
- leismaniases

  • visceral leismaniasis
  • cutaneous leismaniasis
  • mucocutaneous leismaniasis
  • diffuse cutaneous leismaniasis

- trypanosomiases

  • african trypanosomiasis
  • american trypanosomiasis (Trypanosoma cruzi)