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Define epidemiology.
Describe sources of data for epidemiologists.
- a. study of occurrence and distribution and control of each disease
- b. Distribution: how is the bug spread (blood bourned vs. droplet transmission)
- c. Control: how is it going to affect the population
- d. Discuss the data epidemiologist collect
- i. get it from morbidity and mortality weekly report
- ii. look at doctor's visit - take samples (water, food)
- 1. Goal is to identify the bug so that they can make recommendations - about occurrence, distribution, and spread of disease
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Describe the role of public health officials. Describe several strategies including reservoir control and vaccination in decreasing transmission.
- is the public at risk? They assess and advise.
- Assess: they look for a reservoir - site where disease can survive. often an animal. there are non-living reservoires - soil, water. humans are only source for measles.
- Action: avoid reservoir, boil your water. vaccinate. food recalls.
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Differentiate between prevalence vs. incidence.
- Prevalence: proportion or % of disease in the population at a given time
- Incidence: the number of cases of an individual disease at a particular time
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Differentiate between mortality vs. moribidity vs. comorbidity.
- mortality: incidence of death in the population
- morbiditiy: incidence of disease in the population, fatal and non-fatal
- comorbidity: the simultaneous presence of two chronic diseases or conditions in a patient. other diseases ppl might have that affect the diseases you are studying.
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Differentiate between endemic, epidemic, and pandemic diseases.
- endemic: constantly present, but with low morbidity in population
- epidemic: unusually high numbers found in localized population
- pandemic: an epidemic that spread to a large global area, to all continents
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differentiate between virulence, pathogenicity, and infectiousness.
- virulence: measure of number who die
- pathogenticity: number exposed vs. those who get the disease clinically (high - every1 is expected to get the disease)
- infectiousness: how many catch disease, not necessarily clinical
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1. State the significance of reservoirs of disease. Give an example of a disease with a human reservoir, animal reservoir and inanimate reservoir. Identify which would be easiest to eradicate.
- Reservoirs: sites in which viable infectious agents remain and from which infection of individuals may occur
- small pox, polio - humans as reservoir - easiest to eradicate
- bubonic plague- animal reservoir
- Clostridium tetani - inanimate reservoir
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List the 5 stages of an infectious disease and describe each stage.
- 1. infection of the pathogen - pathogen enters and begins growing in host
- 2. incubation period - time between infection and 1st sign of symptoms
- 3. acute period - disease is at its peak with obvious symptoms
- 4. decline period - disease symptoms are subsiding
- 5. convalescent period - pt regains strength and returns to normal health
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Host, agent and environment impact the spread of disease. In this class we will focus on agents.
- host - humans
- environment -reservoir
- vector - are able to carry bug. Transmits disease from environment to host.
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4th factor is the spread of some diseases is the presence of a vector. What role do vectors play in infectious disease. List several examples of vector-transmitted diseases.
- vector: living agents that transmit disease
- most vectors for human disease are arthropods (mosquitos, ticks, fleas)
- west nile, malaria
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Identify the role of carriers in spread of infectious disease.
- carriers are vectors, usually are not affected by the agent, but just trasnmit the disease to the host.
- a person who had disease but don't have symptoms
- i. early in disease or in normal flora.
- ii. can have strep bacteria in normal flor and not show signs.
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What does the iceberg phenomen refer to? how does this impace surveillance of emerging disease?
check written notes.....
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differentiate betwee and give example of each.
- direct host to host transmission & indirect host to host transmission
- a. direct - cough on you
- b. indirect - cough on pen and touch pen....
- common source vs. host to host epidemics
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State how herd immunity can protect susceptible individuals.
populatio protected then you are protected. Takes between 70-95% protection depending on the bug.
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Define nosocomial infection. Describe the chain of transmission than contributes to nosocomial infections.
- hospital based infections
- 5-20% of pateitns are affected
- chain - lots of sick ppl going in and out
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List several reasons for emergence and reemergence of pathogenic diseases.
- some are new viral generome. SARS
- populations have been exposed for centuries but new bugs are drug resistance
- old diseases now being able to be identified
- new diseases now becoming discovered
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BEINGS describes the major catergoreies of risk factors for disease. List and understand each.
- Biological, behavioral
- environmental factors
- immunoglocial factors
- nutrition
- genetic factors
- services (can't reach doctor), social, spiritual (belief)
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Viruses
an infective agent that typically consists of a nucleic acid molecule in a protein coat, is too small to be seen by light microscopy, and is able to multiply only within the living cells of a host : [as adj. ] a virus infection.
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bacteria
a member of a large group of unicellular microorganisms that have cell walls but lack organelles and an organized nucleus, including some that can cause disease.
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fungi
any of a group of unicellular, multicellular, or syncytial spore-producing organisms feeding on organic matter, including molds, yeast, mushrooms, and toadstools.
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parasites
an organism that lives in or on another organism (its host) and benefits by deriving nutrients at the host's expense.
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strain vs. species
- strain: a breed, stock, or variety of an animal or plant developed by breeding.• a natural or cultured variety of a microorganism with a distinct form, biochemistry, or virulence.
- species: 1 (abbr.: sp., spp.) Biology a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. The species is the principal natural taxonomic unit, ranking below a genus and denoted by a Latin binomial, e.g., Homo sapiens.
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Review growth characteristics of bacteria
on enriched, selective and differential media. Understand terms used to
describe colony morphology, fermentation, and hemolysis of red blood cells.
- Enriched- grows many
- Selective- some grow
- some don’t
- Differential- everyone
- grows BUT they look different
- Blood agar-
- differential
- Alpha hemolysis-
- colonies have green halos
- Beta hemolysis-
- complete with clearings
- Gama hemolysis- NO
- hemolysis, colonies look normal
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Microscopic appearnace of indiv. bacterial cells in terms of shapes and arrangement.
- shape
- cocci: round
- bacillus: rod
- spirullum: spirals
- spirachete - special spirillum - very axial filament
- arrangements
- trepto - chains
- diplo - pairs
- staphylo - clumps
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A common first step in bacterial
identification is the Gram stain. What structure are you staining? How does a
Gram positive cell stain? Gram negative?
Stain cell wall
- Gram positive =thick cell wall stain with crystal violet, iodine is mordant crystallizes, alcohol
- blows away lipid bilayer (decolorize), counter stain with saphrin
- Gram negative = pink, thin layer.
- endotoxin is what reacts in body- gives you fever. LPS- lipopysacharide
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Describe the role of bacterial glycocalyx.
made up of capsule and slime alyer. both increase virulence.
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what are fimbriae and pili?
- fimbriae: bristles for sticking
- Pili: genetic transfer - bacteria that can make pili have F plasmid "fertility"
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are spores produced by Gram + or Gram - bacteria? What is the purpose of a spore? What is inside a spore?
- for survival only
- bacillus and clostridium cuz they are super hardy so you can't get rid of them
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Define obligate aerobe, obligate anaerobe, and facultative anaerobes in terms of oxygen use and enzymes present.
- Some organisms are aerobes - can use oxygen
- oblicgate aerobes - ust have oxygen in order to make ATP
- facultative anaerobes - ferment or use oxygen which is aerobic
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Review the three pathways bacteria use to
break down glucose. State which are aerobic, which are anaerobic. Understand
the net energy yield of each.
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What is the purpose of an operon? What is
the difference between inducible and repressible operons? Using the lac operon
as an example, state the function of the promoter, sigma factor, operator,
inducer, repressor.
- inducible - OFF but can be turned on
- Repressible - ON but can be turned off
- Lac Operon is inducible - OFF
- 1. if Lactose is present the repressor is OFF and the operator can transcribe genes.
- 2. cAMP increases if no glucose is presnt. camp binds CAp and increases prommotor binding = transcription and translation
- 3. signma factors allow and are needed for RNA polymerase binding
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Describe each of these 3 mechanisms of gene transfer: conjugation, transformation and transduction.
- a. transformation - bacteria can take up DNA and incorporate it. THey can get a capsule to increase virulence. Can take it from anywhere.
- b. Conjugation - swapping genes. Pili- plasmids for antibiotic resistance
- c. transposons - jumping genes. have been known to have negative effects and turn off genes.
- d. viral transduction - carrying of genes (bacteria can be affected by viruses.
- bacterial virus - viral phages
- restriction enzymes - cut up foreign DNA
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Serotyping.
- A particular strain of bacteria can be distinguished using antibodies to detect characteristic antigens on the bacteria.
- used to identify organisms that are difficult or too dangerous to grow in lab
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Describe primary, secondary and tertiary prevention.
- Primary: strategies intend to avoid development of disease
- Secondary: attempt to diagnose and treate an existing disease in early stage before results in significance morbidity
- tertiary: reduce the negative impact of estbalished disease by restoring function and reducing disease-related complications
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contrast the size of bacterial cell with eukaryotic cells. State size of an average bacterial cell.
average bacterial cell = 0.2 micron vs. animal cell between 10-100 micro meter
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Review cell wall of Gram + and gram - bacteria.
- gram + = stain blue, high amount of peptidoglycan in cell wall. lack the outer membrane. cytoplasmic lipid membrane, thick peptidoglycan layer with teichoic acids and lipoids, capsule polsacchardies, flagellum in some
- teichoic acids - bacterial polysaccharides. found w/in cell wall of gram + bacteria
- gram - = stain pink, cytoplasmic membrane, think peptidoglycan layer, outer membrane containing lipopolysacchardie, porins (pores ), perplasmic space, S-layer
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Which type of bacteria produce spores? what is inside a spore?
- gram +
- DNA is inside spores
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seroptying? what is the role of antibody in serotyping? what does antibody recognize?
- serotype = distinct variations w/in a subspecies of bacteria of virus
- classfied together base on surface antigens
- determinng species and subspecies
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diploid/haploid, packaging on histones/polyamines (spermine), organization of genes in chromosomes/operons, presence or absence of plasmids.
polyamines = helps DNA condenses in vitro
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