Staphylococcus aureus is a microbe that interacts with humans all the time. During the times when it causes disease, it becomes one we wish we didn't have to experience.
Photo by Janice Haney Carr, CDC
Centers for Disease Control and Prevention
The Centers for Disease Control deal with diseases of all kinds, including those caused by bacteria, eukaryotes and viruses. The focus here is on viruses, the definition of living vs. non-living and non-viral, disease-causing microorganisms.