Lab 14' Simulated Epidemiology

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Lab 14. Simulated Epidemiology
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Epidemiology

• The study of the distribution and determinants of
  health-related states or events in specified
  population and the application of this study to
  control health problems.

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Epidemiology

• Diseases are not randomly distributed
• There are causes
• Diseases causation is multifactorial
• A multitude of factors conspire to create an
  environment in which diseases occurs
• Identifying and measuring the relative
  contribution of these factors is a central focus
  of epidemiology Estimate their effects.

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Epidemiologic triangle

• Disease host agent environment
• No disease if no susceptible host
• No disease if no causal agent
• No disease if environmental conditions not
  appropriate

http//www.nwfsc.noaa.gov/research/divisions/ec/ec
otox/immuno2.jpg
http//homepage.usask.ca/vim458/virology/stud2005
/hendra/epidemiologytriangle.gif
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Measure of occurrence

• Incidence
• Number of NEW cases that occur in a population in
  a given period of time
• Prevalence
• Number of cases ALREADY present in a population
  at a given time

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Transmission of contagious disease

• Contagious disease transmitted person to person
• Aerosol or air-borne droplet in the air
• Fecal-oral route
• Can be indirect you touch something that someone
  with a disease touched previously and bring your
  hand to your mouth
• Sexual
• Blood-borne
• Can be transmitted by insect (vector)
• Mechanical
• Biological
• Mother to fetus (via blood stream or milk)

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Vocabulary

• Endemic The habitual or usual presence of a
  disease within a given geographic area. Epidemic
  Occurrence of a disease clearly in excess of a
  normal expectancy
• Pandemic worldwide epidemic ? AIDS

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Objective stimulated epidemic

• We are looking to find the index case (who
  started the epidemic)
• Wear gloves
• Divide one Nutrient Agar Plate into 5 sections,
  numbered 1 to 5
• Take your swab without touching the cotton
• Take one tube and record the number/letter
• You have a culture of
• Serratia marcescens or
• No bacteria
• Put the swab into the culture and rub the palm of
  your left hand with the bacteria culture
• Record the letter of your culture

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Bacteria used for experiment
serratia
http//www.arches.uga.edu/dlg/pigmentml.jpg
http//www.health.qld.gov.au/EndoscopeReprocessing
/images/page_images/1317_serratia.jpg
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Stimulated epidemic

• Shake hands with your left hand with one of your
  classmate ? shake hands so your fingers touch
  his/her palm
• After shaking hands touch the segment one of your
  plate
• Record who you shake hands with
• Do this until all 5 segments of your plate are
  covered
• Be careful to record your contacts

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Stimulated epidemic

• Invert the plate (bottom facing up) and write
  your name and the date at the edge of the plate
• Incubate at 27oC
• Next class we will find which students had the
  culture with the bacteria
• (source of the epidemic)
• Throw your gloves in the plate discard (metal
  container in the back of the class)
• Wash your hands very well