Protozoa can live independently as free-living organisms in the environment, often in the soil, water, or moss. They can also be resting cysts, which lets them survive through dry times. Their main characteristics are:
*They are single celled
*Their cells have membrane-bound nuclei (we call them eukaryotic)
*They lack a rigid cell wall
*They usually lack chloroplasts
Examples of protozoa are Amoeba, Paramoecium, Trypanosoma, Plasmodium, etc. The protozoan parasites Cryptosporidium, Giardia, and Cyclospora have proven potential to cause waterborne and foodborne disease. Toxoplasma gondii has been considered a risk in specific cases, but humans are not its primary host.
Protozoa feed by taking in other organisms such as bacteria and algae or organic particles such as animal or plant debris. They can absorb soluble nutrients such as sugars directly through the cell envelope.
Intestinal protozoa transmitted by consumption of contaminated water and food and mainly affect children and elder people and cause considerable health problems. They live and multiply in the digestive system, irritating the lining and causing pain, fever and diarrhea. Symptoms may appear and disappear for several weeks. They are the leading causes of outpatient morbidity due to diarrhea in the developing countries.
What are protozoa?
