MCB 100 1st Edition Lecture 40Outline of Last Lecture I. Human and animal viruses (cont.) II. Other types of viruses Outline of Current Lecture I. Infection vs. diseaseII. Stages of an infectious diseaseIII. Portals of entryIV. Opportunistic vs. true pathogens V. Virulence and virulence factors Current LectureI. Infection vs. diseasea. Disease = anything that makes you feel badb. An infection is when an undesirable microorganism colonizes the host's bodyc. Infections can be caused by a wide range of microbes but infections do not always cause disease and some diseases are not caused by infections d. Noninfectious diseasesi. Pneumoconiosis- black lung diseaseii. Intoxicationiii. Coronary arterial diseaseiv. Severe combined immunodeficiencyv. Strokesvi. Depressionvii. Alcoholismb. Infectious diseasesi. Communicable- malaria, flu, gonorrhea, TB ii. Noncommunicable- tetanus, rabies, lyme diseaseII. Stages of an infectious diseasea. Encounteri. Microorganism gets into the hostb. Incubation periodi. Pathogen begins growing in the host's body, no symptoms are seenb. Prodromal periodi. First symptoms appear, often mild a. Illness (aka: acute phase) These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. Worst signs and symptoms are seen b. Decline (aka: resolution)i. Immune response and treatment reduce the number of pathogens a. Convalescencei. Patient recovers, may take time I. Portals of entrya. Breaks in the skini. Physical wounds- dirt, tetanus, gangrene, burn infections ii. Animal bites- rabies, malaria, lyme disease, typhusb. Mucous membranes i. Mouthii. Nose- strep throat, common cold, TB, fluiii. Eyes- conjunctivitis, colds, fluiv. Urogenital tract- bladder infections, STDs v. Gastrointestinal tract- diarrheal diseases, ulcers, peritonitis b. Trans-placentali. Starch II. Opportunistic vs. true pathogens a. True pathogen: an infectious microoganism that can cause disease in a healthy human host with a good immune systemb. Opportunistic pathogen: a weaker infectious agent that can cause disease in a host with weakened resistance/immunity but not generally in a healthy hostc. What makes an infectious microorganism a true pathogen is the production of virulence factorsd. Examples of diseases caused by true pathogens: i. Diphtheria (gram + bacteria- corynebacterium diphtheriae) ii. Bubonic plague (gram - bacteria- yersinia pestis) iii. Malaria (protozoan- plasmodium falciparum)iv. Yellow fever (virus- yellow fever virus) b. Example of a disease caused by an opportunistic pathogen: i. Hospital acquired septicemia due to serratia marcesces contamination of IV-TPN solutionII. Virulence and virulence factorsa. Virulence: the ability of a microorganism to cause diseaseb. Virulence factor: a substance that a microorganism makes that increases its ability toinfect or damage a hosti. Many virulence factors are proteins ii. Virulence factors fall into 2 broad categories:1. Invasins: help microorganisms enter a host or evade the host's defenses2. Toxins: poisons/enzymes that damage the hostii. Examples of virulence factors:1. Flagella: allow bacteria to move. Motility helps bacteria to spread (such as up the urethra)2. Capsules: slimy layer of polysaccharides can mask surface antigens and reduce the attachment of antibodies; also help bacteria to form a
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