Protozoa are one of the three main classes of parasites that cause diseases in humans. They are single-celled organism, and can only be seen under a microscope. When they invade a human they are able to multiply easily, which causes them to be at a great advantage and puts humans at a disadvantage. This helps them survive in the human body and causes a serious infection even with the arrival of a single protozoon.
Infections caused by protozoa are contagious. Those protozoa that have inhabited the human intestine can be transmitted from one human to the other via the fecal-oral route, such as through sharing food the infected person has touched and through direct person to person contact. Protozoa living in the blood or tissue can be transmitted through a third source such as a mosquito. Infections are easily transmitted and persons carrying this parasite should avoid interactions with others, especially those with compromised and weakened immune systems.
There are four main groups of protozoa that cause infection in humans. They have been grouped according to how they move:
1. The sarcodina (amoeba)
2. Mastigophora (flagellates)
3. Ciliophora (ciliates)
4. The Sporozoa