In this chapter you will learn what a disease is and how it spreads. In addition, Koch's postulates on how to identify different types of disease-causing agents and the diseases they cause will be described. You will also explore the causes and types of treatment for cancer.

In this chapter, you will: define disease and describe how it may spread explain how infectious diseases are grouped list diseases caused by viruses, bacteria, fungi, and protozoans describe some of the causes of cancer