In this deck, we'll explore the world of communicable diseases. You'll learn what a pathogen is, how these microorganisms cause illness, and the four main types: viruses, bacteria, fungi, and protists. We'll also look at specific examples of diseases, from measles and HIV to malaria and rose black spot, covering how they are spread and the symptoms they cause.

Pathogens come in four main varieties. The smallest are viruses, which are not truly alive. Then there are bacteria, which are single-celled living organisms. Fungi, which can be single-celled like yeast or multi-cellular, can also be pathogens. Finally, there are protists, a diverse group of eukaryotic organisms. Let's look at each type in more detail.

Viruses are tiny particles, much smaller than bacteria. They can't reproduce on their own. Instead, they invade living host cells and use the cell's machinery to make copies of themselves. This process often damages or destroys the host cell, which is what makes you feel ill. Let's examine three diseases caused by viruses.