It's not accurate to say there are just "two main microbes" that cause disease. There are actually thousands of different microbes that can make us sick. However, two broad categories of microbes are responsible for a vast majority of human diseases:

1. Bacteria: These are single-celled organisms that lack a nucleus and other internal structures found in more complex cells. They are incredibly diverse, and some bacteria are beneficial while others can cause infections like pneumonia, food poisoning, and urinary tract infections.

2. Viruses: These are even smaller than bacteria and are essentially genetic material (DNA or RNA) wrapped in a protein coat. They can't survive on their own, and they must hijack a host cell's machinery to replicate. Viral infections include the common cold, influenza, HIV, and COVID-19.

While these two categories are the most common culprits, it's important to remember that other microbes, such as fungi, parasites, and prions, can also cause disease.