Table of contents

Intro

Parasites form a complex and diverse group of organisms. This article points out key characteristics of human parasites as a starting point for understanding them. An overview of their structure, life cycle, reproduction and metabolism is made. We will also look at their scientific nomenclature.

Note: Drawings are not to scale.

A common ancestor, through an evolutionary process of more than 3 billion years, gave rise to organisms that today we group into three domains:

• Archaea,
• Bacteria,
• Eukarya (includes animals, fungi, plants and protozoa).

Human parasites belong to the animals and the protozoa groups.

Animals = Metazoa

Protozoa = Protists