In this chapter you learn how to differentiate intestinal protozoa, helminth ova, plasmodia and microfilariae by using specific morphological criteria. The diagnostic keys presented here are those of the Diagnostic Centre of the Swiss Tropical and Public Health Institute (Swiss TPH) in Basel. Of course, each laboratory has created its own keys and you should also consult diagnostic text books or keys provided by WHO to find out which keys suite you best for your daily work.

• Under “Key Diagnostic Features” you find a list of important diagnostic criteria and pencil drawings of the parasites
• Under “Diagnostic-Keys” you find printable versions of our keys
• Under “Exercises” you get photo-micrographs in a random order and you have the opportunity to work with the keys