g. Examine the role of the human leukocyte antigen (HLA) in solid organ rejection. Human leukocyte antigen (HLA) : Immune response against antigens on donated tissue Type IV cell mediated reaction (rejection within 2 weeks w/o immunosuppressive drugs **Matching HLA-DR locus appears to be most critical for graft acceptance
Infection 9. Analyze the concepts of infectious disease. h. Examine the process of infection: Colonization, invasion, multiplication and spread Concept Process Description Colonization Germs found in the body that do not make you sick (No s/s) -can be transmitted in many ways direct contact, mechanical vectors (house flies), biologic vectors (lice, fleas, mosquitoes), direct exposure to contaminated materials (fecal- oral transmission through food/water (salmonella poisoning, hep A, cholera), human to human- droplet, direct contact (STIs, hep B, herpes), airborne transmission Invasion Once colonization has occurred the infectious disease agent can invade the surrounding tissue and other sites in the individual -Infectious agents have mechanisms that penetrate the tissues and evade the host’s non-specific and specific defenses (inflammation and immunity) Multiplication Can undergo rapid multiplication with production of many new infectious progeny -Viral pathogens replicate within infected cells -Bacteria are intracellular pathogens, replicate in macrophages and other cells Spread Some are highly invasive and may enter through lymphatics, blood, and internal organs -Successful spread relies on: adhesion molecules, toxins, protection against individual’s inflammatory & immune systems (rapid spread if immunocompromised) i. Analyze the following infectious disease terms: Concept Definition Incubation period When the pathogen begins active replication (initial colonization, begins multiplying) -No clinical manifestations -Highly dependent on the microorganism -Salmonella (6-8 hours), Hepatitis B (50-180 days) Prodromal stage Characterized by initial appearance of clinical manifestations (mild) Invasion period Rapid multiplication of the organism & activation of the immune & inflammatory responses -Will begin having organism specific clinical manifestations & inflammation manifestations Convalescence Containment of infection *Resolution of symptoms (however, there are exceptions) -Fulminant presentation with little or no prodromal stage -Subclinical infection with no symptoms -Acute infections > evolving into chronic infection Communicability Ability to spread from one individual to others & cause disease Measles, pertussis (easily spread)
HIV (lower communicability) Immunogenicity Ability of pathogens to induce an immune response Infectivity Ability of pathogen to invade & multiply in the host Pathogenicity Ability of an agent to produce disease Success depends on communicability, infectivity, extent of tissue damage, virulence Portal of entry Toxigenicity Ability to produce soluble toxins or endotoxins, factors that greatly influence the pathogen’s degree of virulence Virulence Capacity of a pathogen to cause severe disease
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