Pathogenesis of Infectious Diseases

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PATHOGENESIS OF INFECTIOUS DISEASES Chapter 14Learning objectives • After studying this chapter, you should be able to: • Cite four reasons why an individual might not develop an infectious d... isease after exposure to a pathogen • Discuss the four periods or phases in the course of an infectious disease • Differentiate between localized and systemic infections • Explain how acute diseases differ from subacute and chronic diseases • Differentiate between “symptoms” and “signs” of a disease and cite several examples of each • Cite several examples of latent infections • Differentiate between primary and secondary infections • List six steps in the pathogenesis of an infectious disease • Define virulence and virulence factors • List six bacterial structures that serve as virulence factors • List six bacterial exoenzymes that serve as virulence factors • Differentiate between endotoxins and exotoxins • List six bacterial exotoxins and the diseases they cause • Describe three mechanisms by which pathogens escape the immune response 2Pathogenesis of infectious diseases • The prefix “path-” means disease • Pathogenicity – ability to cause disease • Pathogenesis – the steps or mechanisms involved in the development of a disease • An infectious disease/infection is the disease caused by a microbe • Microbes that cause the disease are known as pathogens • Microbiologists use the word infection to mean colonization by a pathogen • Pathogen may or may not cause a disease in the person • Therefore a person can be infected with a pathogen and not have the infectious disease caused by it 3Why infection does not always occur • Wrong anatomic site • Lack of appropriate receptors • Presence of antibacterial factors • Ex: lysozyme • Presence of indigenous microflora • Microbial antagonism • Bacteriocins • Good health of host • Host humoral immunity • Previously infected by it/vaccinated • Host cellular immunity 4Four Phases of Infectious Disease I. Incubation period • Time between arrival of pathogen and onset of symptoms II. Prodromal period • Patient feels “out of it” III. Acute phase (period of illness) • Patient experiences the typical symptoms associated with the disease • Communicable diseases transmit easily during this phase IV. Convalescent phase • Patient is recovering • Damage can be permanent [Show More]

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