Infectious agents come in many shapes and sizes. Bacteria and protozoans are microscopic one-celled organisms. Viruses are even smaller. Fungi grow like plants. Helminths resemble worms.
Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission.
Check out these best-sellers and special offers on books and newsletters from Mayo Clinic Press.
Your gift can go twice as far to advance cancer research and care!