Large group of unicellular animals which are bigger and more
complex than bacteria.
Undetectable to naked eyes, most of them are around 0.01-0.05 mm. Examples
include amoebas and flagellates.
Protozoa can cause diseases such as malaria and sleeping sickness.
Untreated water may be contaminated with
protozoa some of which may not be killed by disinfection alone.
Cell - Disinfectant(s) - Micro-organism