BIOL 202 Lecture 8: Chapter 19: Infection and Disease

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Biological Science
BIOL 202
Cathie Overstreet

Chapter 19. Infection and Disease • CDC • WHO o Employ epidemiologists; disease investigators. o Try to prevent disease; halt the spread of epidemics. o Prevention strategies; clean filters, isolate people, etc… • In the 1970s, it was thought that infectious disease was going to be eradicated. o However, this statement was made before the prominence of antibiotics resistant bacteria and new emerging diseases without treatment (HIV, Ebola, Zika). Microbes are Everywhere • Microbiota: the population of microorganisms the reside normally in the body without causing disease. o Colonization bacteria; competes for the same nutrients. o Secrete antimicrobial compounds. o Microbiota are received from birth and remain until death. • Terminology: o Indigenous: have permanent relationship with body. ▪ E. coli, C. albicans. o Transient microbiota: temporary, found only for limited periods of time. ▪ Streptococcus. o Symbiosis ▪ Mutualism: beneficial to both host and microbe. ▪ Commensalism: beneficial only to the microbe and the host is unaffected. ▪ Parasitism: pathogen causes damage to host, potentially causing disease. • Chlamydiae. • Surgeries, wounds, and other injuries can introduce pathogens to the body, possibly replacing the body’s natural microbiota. o Antibiotics and other drugs can have the same effect. • Protection of microbiota: o Probiotics; avirulent, nonpathogenic microbes similar to gut microbiota. o Competes with pathogen and restore microbiota. The Host-Microbe Relationship • Inflammation is the first sign that the immune system is beginning to kick in. • Anything that alters the normal good healthy behavior of the body is a disease causing agent. o If you have a pathogenic bacteria but are not affected by the disease negatively, you are not really diseased. Sterile Tissues • Blood • Bone • Cerebrospinal fluid • Joint fluid o Ex. knee, ankle, hip, wrist, ankle. • Internal organs o Ex. kidneys, liver, muscles, lymph node, brain, heart, spleen, pancreas, ovary. Any Microorganism Can Become Virulent • Microorganisms can change genetically and become virulent. • Can obtain virulent genes located on plasmid from another microbe through conjugation. Progression and Outcomes of Infection and Disease • Primary: occur in healthy bodies. 2 • Secondary: occur in body weakened by a primary infection. o Example: 1918-1919 influenza pandemic. • Local: focused area of infection upon a single area of the body. • Systemic: focus of infection to organs and systems via blood. o Example: Staphylococci. “-Emia”: Blood • Bacteremia: transient appearance of bacteria in blood. • Septicemia: growth and spread of bacteria in blood. o Potentially life threatening; bacterial division occurs very fast. • Viremia: detection of viruses in the blood. • Toxemia: presence of toxins in the blood. Establishment of Infection and Disease • Diseases progress through a series of stages. o Signs (detected by observer), symptoms (observed by patient), and syndromes (signs and symptoms together; characterize disease). • Course of Disease: o Acute: develop quickly and fades away quickly. o Chronic disease: lingers; slow to develop and slow to recede. The Body Is Composed of Portals • Pathogens enter and leave the host through orifices on the body. • Pathogens can spread thro
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