医学英语 感染病.ppt

Introduction to infectious diseases Gang XIN Department of Microbiology and Immunology gxin@terms Outline Pathogen Host Pathogenesis of infection Classification of infection Clinical manifestations Laboratory diagnosis of infectious diseases Treatment and prevention Types of pathogens prion Viruses Bacteria (singular: bacterium) chlamydiae rickettsiae Symptoms of Scrub typhus fever headache muscle pain cough gastrointestinal symptoms hemorrhaging and intravascular coagulation. maculopapular rash, eschar（焦痂）, splenomegaly and lymphadenopathies are typical signs. Mycoplasma Spirochete Fungi (singular: fungus) arthropods Greek arthron, joint, and podós foot, which together mean jointed feet” Pathogen factors The virulence factors of bacteria The virulence factors of bacteria Adhesion. Many bacteria must first bind to host cell surfaces.. Colonization. Some virulent bacteria produce special proteins that allow them to colonize parts of the host body. Invasion. Some virulent bacteria produce proteins that either disrupt host cell membranes or stimulate endocytosis into host cells. These virulence factors allow the bacteria to enter host cells and facilitate entry into the body across epithelial tissue layers at the body surface. Immune response inhibitors. Many bacteria produce virulence factors that inhibit the hosts immune system defenses. Toxins. Many virulence factors are proteins made by bacteria that poison host cells and cause tissue damage. Host factors Infectious disease spectrum If a large number of individuals are equally exposed to an infectious agent, they do not all respond in the same manner. In fact, there may be a broad range of responses: Some do not become infected at all Some become infected but develop no symptoms Some become infected and develop mild or moderate symptoms Some become infected and develop severe symptoms Some die as a result of their infection Clinical manifestations of infectious diseases Host-Pathogen In