Protozoan Parasites

• Protozoa are eukaryotic and structurally more complex than prokaryotes. They have chromosomes within a nuclear envelope along with membrane bound organelles and a cytoskeleton. The classification of these parasites is complex and covers different groups and lineages because few general characteristics apply to all of them.
• Sporozoite = infective stage

  Trophozoite = stage in host which feeds and grows until division commences
• • Direct - Transmitted from one host to another. E.g. Eimeria species
  • Indirect - Requires an intermediate host or vector. E.g. Leishmania species
• Apicomplexa are obligate parasites of almost all animal species with specialised organelles on the sporozoite to penetrate host cell.
• Apicomplexa are unicellular and spore forming with motile structures only present in certain gamete stages. Even without flagella, they use a gliding mechanism.
• Babesia is a tick borne disease of cattle which can multiply in red blood cells. There are multiple species of interest including cattle, dogs, and horses.
• Babesiosis is pathogenesis and causes ‘Redwater fever’ or ‘Texas fever’.
• Coccidiosis is caused by a protozoan parasites known as Eimeria. It infects intestinal epithelium with no intermediate host. Schizogony and gametogony stages both occur within the host. The sporulation of the zygote (oocyst) occurs in environment.