Infectious diseases are among the top causes of death in adults and children. Chronic diseases such as cardiovascular disease and cancer are among the top causes of death in adults. Associations between bacterial and viral infectious agents and subsequent development of chronic disease have been made in the past but are currently being reexamined with more rigor and specificity. This review examines infectious disease agent causes and associations with cancer, cardiovascular disease, metabolic disease, and neurodegenerative disease. These associations will impact future research, surveillance, treatment, and prevention of both infectious and chronic diseases.