Porth's Essentials of Pathophysiology, 4e

4 Infection and Immunity

U N I T

ll living creatures share two basic objectives in life: survival and reproduction. This doctrine applies equally to bacteria, viruses, fungi, and protozoa. To satisfy these goals, organisms must extract from the environment essential nutrients for growth and prolif- eration; for countless microscopic organisms, that envi- ronment includes the human body. The content in this chapter has been divided into four parts: (1) general concepts of infectious diseases, (2) epi- demiology of infectious diseases, (3) general principles of diagnosis and treatment, and (4) new and emerging infectious diseases. Mechanisms of Infectious Disease A General Concepts of Infectious Diseases Normally, the contact between humans and microor- ganisms is incidental and, in certain situations, may actually benefit both organisms. Under extraordinary circumstances, however, the invasion of the human body by microorganisms can produce harmful and potentially lethal consequences. The consequences of these inva- sions are collectively called infectious diseases . Terminology All scientific disciplines evolve with a distinct vocabu- lary, and the study of infectious diseases is no exception. The most appropriate way to approach this subject is 14 C h a p t e r

General Concepts of Infectious Diseases Terminology Agents of Infectious Disease Prions Viruses Bacteria Rickettsiaceae, Anaplasmataceae, Chlamydiaceae, and Coxiella Fungi Parasites Epidemiology of Infectious Diseases Mechanisms of Transmission Portal of Entry Source Mechanisms of Disease Production Toxins Adhesion Factors Site of Infection Disease Course Diagnosis of Infectious Diseases Culture Serology Protein Detection DNA and RNA Detection DNA Sequencing Treatment of Infectious Diseases Antibacterial Agents Antiviral Agents Antifungal Agents Surgical Interventions New and Emerging Infectious Diseases Global Infectious Diseases Evasion Factors Invasion Factors Clinical Presentation

297