HLTH 103 - Biological Determinants of Infectious Disease & Immunity PDF

HLTH 103 – Biological Determinants of Infectious Health Disease & Immunity Health Sciences Outline of Topics PART A: Focus on MICROBES  Microbes & Microbiome (10.1)  Antibiotic Resistance (10.2 & 14.5) PART B: Microbes & HUMANS  Virulence & Illness (10.3)  Pathogens (10.4) PART C: CO...

HLTH 103 – Biological Determinants of Infectious Health Disease & Immunity Health Sciences Outline of Topics PART A: Focus on MICROBES  Microbes & Microbiome (10.1)  Antibiotic Resistance (10.2 & 14.5) PART B: Microbes & HUMANS  Virulence & Illness (10.3)  Pathogens (10.4) PART C: CONTROL  Controlling Disease (10.5, 14.4 & 14.6) Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Microbiome  Your body is made up of around 100 trillion cells, with only 10 trillion being yours. The other 90 trillion cells are bacteria and other one-celled organisms.  One study found 182 species of bacteria living on the forearm alone.  Ecology is the study of the interactions among species and their environments. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Microbiome  Commensalism: one species benefits from the interaction, the other is neither helped nor harmed.  e.g. mites in your eyebrows  Mutualism: both species benefit from the interaction.  e.g. bacteria in your digestive tract Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Microbiome  If conditions change, these interactions can also change.  One example is the bacterium Pseudomonas aeruginosa. It can live on you and cause no damage. If a person is already sick, it can cause necrosis (tissue death) when they reach a quorum, or a population large enough to overcome the body’s defenses.  Some species don’t have switches and will always cause disease. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Infectious Disease Agents - Bacteria  We are surrounded by various types of microorganisms.  Some of them are prokaryotic (no membrane-bound organelles).  These prokaryotic organisms can help us (digest food) or hurt us (cholera, tuberculosis, cholera). Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Infectious Disease Agents - Parasites  Other microorganisms are protozoans, single-celled eukaryotic organisms.  Examples include giardiasis, amoebic dysentery, and malaria.  Multicellular eukaryotic examples include fungi that cause yeast infections, athlete’s foot, and ringworm. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Infectious Disease Agents - Viruses  Viruses and prions are other pathogens, but these are not even alive.  Viruses have to replicate inside their host’s cell. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Infectious Disease Agents - Prions  Prions are self-replicating proteins.  Some prions are normally found in the brain.  Can be transformed into pathogens that can cause mad cow disease, Creutzfeldt-Jakob disease. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Antibiotics Resistance  Penicillin was discovered by Andrew Fleming in 1928, and widespread use began in 1943.  More and more bacteria are now resistant to penicillin and the other antibiotics that have since been developed.  The few bacteria that don’t die when antibiotics are applied form a resistant population. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Antibiotics Resistance  Most antibiotics occur naturally, made by bacteria, molds, and other species.  By killing other organisms, the species that produces the antibiotic has more food for itself. This species also has to be resistant to it.  If they evolved resistance to these antibiotics, other species can do the same. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Antibiotics Resistance  Organisms possess resistance genes &/or acquire mutations  Four mechanisms of resistance: Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Antibiotics Resistance  Horizontal Gene Transfer:  Transformation  Transduction  Conjugation Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Antibiotics Resistance  Although antibiotic resistance provides an advantage, it does so at a cost.  Resistant cells need energy to be resistant. This energy is diverted from other processes, like growth and reproduction.  This is why not all bacteria are resistant. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Antibiotics Resistance – environmental considerations Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Antibiotics Resistance Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Virulence & Illness  Pathogens vary in their virulence  Virulence: ability to cause damage or death.  Pathogens can also change their virulence.  Example: Myxoma  Pathogenic to rabbits  Initially killed 99% of infected rabbits.  Now it only kills ~50% of infected rabbits. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Virulence & Illness Evolution of disease:  Natural selection selects for increased reproductive success, however it occurs.  Pathogens have a two-pronged challenge for success:  Evolve to reproduce successfully within a host.  Balance this against the need for transmission to a new host. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Virulence & Illness Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Pathogens – emergence  Species can evolve into a new strain that causes disease.  You can contract the diseases of other species.  Species that normally live in soil or water can invade your body. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Pathogens – emergence Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Resistance – Pathogens – CONTROL  Chain of Infection Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Controlling Disease  Vaccinations have been used successfully for mumps, measles, polio, and chicken pox.  Other diseases prove difficult to control through vaccines. These are pathogens that mutate rapidly, and thus the immune system can’t recognize it.  Example: Diphtheria vaccine created from bacterial toxin Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Controlling Disease  Vaccinations: we administer material to provoke the development of immunity to a specific pathogen.  Vaccinations have been used successfully for mumps, measles, polio, and chicken pox.  Vaccines are composed of these surface proteins or other parts of the pathogen that will be recognized by the immune system. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Controlling Disease  Natural immunity: immunity that occurs as a result of having recovered from a previous bout with an infectious disease.  Passive immunity: the temporary transfer of antibodies from one individual to another; for example, the antibodies that circulate in a mother’s blood can cross the placenta and enter the fetal bloodstream. Breast milk also has antibodies that help the baby. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Controlling Disease Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Scientist Spotlight: Anthony S. Fauci  He was the point person for the fight against HIV/AIDS.  When demonstrators stormed the campus where he worked, he invited the leaders to come in and talk.  This led to the participation of activists in many phases of planning and the development of new models for testing treatments.  Dr. Fauci made differences not only as a leader but as a scientist, too. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Controlling Disease  Wellness: disease spreads more easily through a weakened population.  Hygiene: practicing good hygiene can prevent the spread of the disease, even during an outbreak.  Clean water and sewers: when human waste doesn’t have the chance to seep into drinking water, cholera and other types of infectious diseases disappear. Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press Adapted From: Bozzone, Biology for the Informed Citizen, © 2014 by Oxford University Press