• Single celled eukaryotes (nucleus): animalia, plantae, fungi, protista... including protozoa (either free-living or parasitic)

• Protozoa is (1) motile (2) unicellular (3) eucaryote

Some protozoa have two-phase life cycles, alternating between proliferative phases (troph) and dormant cysts

• Trophozoite (trophe, nourishment + zoon, animal): activated feeding stage in the life cycle of certain protozoa e.g Giardia (quickly die in the environment)

• Cyst: infectious form (dormant stage that can survive in the environment)

Protozoan parasites that infect human:

Amoeba

Amoeboid motility (e.g. pseudopods), asexual reproduction (binary fission). 

• Intestine (large): E.histolytica  (cysts/trophs); Tissue (CNS, cornea): Free-living amoeba

Flagellata

Flagellar (flagellum, whip) motility, asexual reproduction (binary fission)

• Intestine: giardia (cysts/trophs), vagina/urethra: trichomonas vaginalis (trophs)

• Kinetoplastida (flagellata characterised by the presence of an organelle with a large massed DNA called kinetoplast): Blood: trypanosoma brucei; Tissue (reticuloendothelial system, CNS): trypanosoma cruzi, (liver, spleen, skin/mucous membrane) Leishmania spp. 4 forms: Amastigote, Promastigote, Epimastigote, Trypomastigote (not leish)

Apicomplexia

• Glilding motility, asexual reproduction and sexual reproduction...(sporozoans)

• Intestine (small): cryptosporidium spp., Isospora belli, Cyclospora

• Blood, RBC: plasmodium spp., Babesia

• Tissue (brain, muscle): toxoplasma gondii

Infectious stages: Sporozoite, Merozoite, Trophozoite, Hypnozoite, Gametocyte