The Host Defense: Mechanisms and Therapeutics module integrates general principles of Pathology, Infectious Diseases, and Pharmacology in an exploration of the basic processes by which injurious stimuli to cells, tissues and organs, especially those produced by infectious organisms, result in disease, and of the general principles by which drugs are used to treat disease. Viruses, bacteria, fungi, protozoa, and helminths are studied as biologic agents of infectious disease. Emphasis is placed on the etiology of disease, life cycles, epidemiology, pathology, clinical symptoms, treatment and prevention of disease.