MBI 405 Lecture 2 (Dr. Carlin) – Flashcards
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| Epidemiology |
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The study of the various factors influencing the occurrence, distribution, prevention and control of disease, injury and other health-related events in a defined human population.
i.e: Where do they come from? How do they get to us? |
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What is a reservoir? What are the 4 types of reservoirs? |
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Continuing sources of disease
Water, Soil, Human, Animal |
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| Water Reservoirs |
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Problem for us: water contamination by feces and urine Solution for us: water treatment sewage facilities Problem for bug: nutrient poor, salinity, temperature Solution for bug: VBNC (viable but not culturable state) Vibrio cholerae ETEC (Enterotoxic E. coli) Campylobacter jejuni Mycobacterium tuberculosis Legionella pneumophila |
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| Soil Reservoirs |
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Problem for us: contact with soil Solution for us: avoid rusty nails and war wash hands immunize Problem for bug: desiccation Solution for bug: endospores Bacillus anthracis Clostridium botulinum Clostridium tetani Clostridium perfringens
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| Human Reservoirs |
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Problem for us: avoiding infected humans Solution for us: immunization quarantine Problem for bug: non-specific defenses immune response Solution for bug: adhesins evasins and evasion strategies |
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| Animal Reservoirs |
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Problem for us: avoiding infected animals animal products Solution for us: immunization and quarantine good animal husbandry food handling Salmonella enterica Campylobacter E. coli O157:H7 Problem for bug: non-specific defenses immune response Solution for bug: adhesins evasins and evasion strategies Salmonella enterica
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| Horizontal Transmission |
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| Direct and Indirect |
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| Vertical Transmission |
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| Transplacental, During birth |
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| Direct Transmission |
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direct methods: requires close or personal contact with infected individual hand-shaking, kissing, sexual intercourse, contact with feces (bacterial STIs, gram -ve intestinal disease) aerosols - exposure to droplets - mucus expelled during cough or sneeze ( Bordetella pertussis, Streptococcal sore throat) exposure to infected animals ( Salmonella enterica, Bacillus anthracis) |
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| Indirect methods |
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vehicles - consumption of contaminated food or water - poultry - source of Salmonella enterica, Campylobacter fomites - inanimate objects that carry pathogens - drinking fountains, used tissues, door handles,phones, used syringes vectors - insects, arthropods - mechanical - transports pathogen (salmonellosis) biological - vector is diseased (Lyme borreliosis) |
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| Communicable disease |
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| Transmissible among hosts |
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| Carrier |
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Has recovered from disease but continues to shed organisms (Salmonella typhi) |
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| Contagious |
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| Pass among hosts with particular ease |
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| Noncommunicable |
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| acquired directly from environment, not easily transmitted to next host (Clostridium spp.) |
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| Endemic |
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| Occurs at a low level in a specific geographic area |
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| Epidemic |
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| A desease that breaks out in explosive proportions in a population |
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| Pandemic |
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| Worldwide epidemic |
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| Symbiosis |
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| A situation in which two populations of organisms interact in a close and permanent association |
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| Synergism |
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two populations live together and accomplish what neither could alone mitochondria and chloroplasts in eukaryotic cells lichens: fungus and algae (green algae or cyanobacteria)
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| Mutualism |
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benefits both organisms nitrogen-fixing bacteria living in plant root nodules Lactobacillus in vagina nutrients and production of acid environment E. coli in intestine supplies vitamin K and metabolizes otherwise indigestible foodstuffs Streptococcal spp. in throat provide “colonization resistance” to Streptococcus pyogenes
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| Commensalism |
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one population benefits, the other neither benefits nor is harmed i.e., normal flora bacteria that inhabit the skin, bacteria that inhabit intestine benefit to host may be unrecognized |
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| Antagonism |
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beneficial to one organism, harmful to the other i.e., pathogens |
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| Infection |
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| Colonization of the body by a bacterium |
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| Disease (due to bacterium) |
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Infection that produces signs and symptoms
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| Signs |
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Objective evidence of damage to the host
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| Symptoms |
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Subjective evidence of damage to the host
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| Normal Flora |
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microorganisms that infect without causing disease an example of symbiosis, either mutualism or commensalism introduced in the birth canal and gradually acquired from environmental exposure outnumber us 10:1 |
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| Significance of Normal Flora |
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| Skin Normal Flora |
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Staphylococcus Micrococcus Corynebacterium Propionibacterium acnes Enterics |
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| Oronasopharynx (ONP) Normal Flora |
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alpha-hemolytic Strep Corynebacterium Micrococcus Neisseria Haemophilus Bacteroides Spirochaetes Mycoplasma |
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| Gastrointestinal tract (GIT) Normal Flora |
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Streptococcus Enterococcus Lactobacillus Clostridium Enterics Bacteroides Pseudomonas |
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| Urogenital tract (UGT) Normal Flora |
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Streptococcus Lactobacillus
Bacteroides
Mycoplasma |
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| Sterile Locations in body |
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| CSF, Blood, Synovial fluid, Lungs, Deep tissues |
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| Endocarditis caused by? |
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| Streptococcus viridans |
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| Dental caries caused by? |
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Streptococcus mutans (sobrinus) Streptococcus gordonii |
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| Abscesses caused by? |
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| Staphylococcus aureus |
