In this figure, we see a variety of pathogenic microbes and the associated disease.:

(a) Human immunodeficiency virus (HIV), which is the cause of AIDS. (b) Influenza virus. (c) Staphylococcus aureus, a bacterium that colonizes human skin, is the common cause of pimples and boils, and can also cause food poisoning.

In these images of a woman, the strong barriers to infection provided by the skin, hair, and nails are colored blue and the more vulnerable mucosal membranes are colored red.