Description of parasitic protozoans with example (protozoan groups).

Parasitic protozoans are unicellular eukaryotic organisms that live in or on a host, obtaining nutrients and causing harm. They are heterotrophic and can reproduce both asexually and sexually. Many have complex life cycles involving multiple hosts.

Here are examples from different protozoan groups:

• Flagellates (Mastigophora): These protozoans move using flagella. An example is Trypanosoma brucei, which causes African sleeping sickness in humans.
• Amoeboids (Sarcodina): These move using pseudopods. An example is Entamoeba histolytica, which causes amoebic dysentery.
• Sporozoans (Apicomplexa): These are non-motile and obligate intracellular parasites. An example is Plasmodium falciparum, the causative agent of malaria.
• Ciliates (Ciliophora): These move using cilia. While most are free-living, Balantidium coli is a parasitic ciliate that can cause balantidiasis.