Lecture Notes on Disease and Epidemiology

Introduction to Scientific Method and Inquiry

  • Discussion on observational phenomena.

  • Example: Coffee stain ring observed after spillage.

    • Observed that stain has a dark ring at the edge.

    • Idea presented that evaporation causes concentration increases.

  • Connection to experimentation and curiosity.

Scientific Method and Variables

  • Importance of testing and inquiry in science.

  • Methodology for graphing data:

    • Independent Variable: The variable that is manipulated or changed.

    • Example: Amount of sleep

    • Dependent Variable: The outcome that is measured.

    • Example: Test scores

  • Cofounding Variables: Variables that may affect the outcome but cannot be controlled.

  • Importance of controlled experimentation to understand cause and effect relationships.

Historical Perspectives on Disease

  • Historical questions in microbiology include:

    • Origins of life and disease.

    • Epidemiology of disease: Why did some towns experience outbreaks while others did not?

  • Mention of critical moments like the COVID-19 pandemic, relating to historical disease transmission.

    • Recognition of how historical epidemics have shaped public understanding of health and disease.

  • Discussion of abandoned towns due to disease impact.

Theories and Misconceptions in Historical Context

  • Discussion of historical theories surrounding disease:

    • Theories of ‘bad air’ and unscientific methods.

    • Witchcraft accusations and societal scapegoating.

  • Importance of the humoral theory, highlighting bodily fluids like phlegm.

    • The belief that balance of humors was essential for health.

Key Historical Figures in Microbiology

  • Anton van Leeuwenhoek and the introduction of the microscope.

  • Louis Pasteur's contributions:

    • Swan's neck experiment demonstrating spontaneous generation.

    • Experiment involved nutrient broth exposed to air.

    • Results debunked belief in life originating from non-living matter.

    • Development of vaccines and understanding of disease immunity.

Insights from Epidemiology and Vaccinology

  • Vaccination development, importance in disease control mechanisms.

  • Challenges faced in culturing certain bacteria:

    • Idea of “viable but not culturable”.

    • Example: Difficulties in growing significant bacteria that aid in health.

  • Discussion on specific bacterial diseases:

    • E. Coli outbreak linked to specific food sources.

    • Understanding how molecular changes can lead to pathogenicity.

Cancer and Environmental Factors

  • Discussion on potential carcinogens:

    • Cigarette smoke noted as a cancer risk factor.

    • Consideration of 'dose dependency' in exposure.

  • Historical context of cell phone use and cancer risk considerations.

Historical Case Studies in Epidemiology

  • Case study: Typhoid Mary (Mary Mallon) and her role in the spread of typhoid fever.

    • Importance of tracing diseases to specific sources in public health.

  • The cholera outbreak and the importance of water sources in disease transmission:

    • John Snow's contributions in tracking cholera in London.

The Role of Scientific Studies in Health

  • Types of epidemiological studies:

    • Descriptive Studies: Analyze outcomes and occurrences without intervention.

    • Analytical Studies: Use retrospective or prospective methods to determine causes.

    • Experimental Epidemiology: Assign treatments to understand effects.

  • Ethical concerns surrounding some relevant studies:

    • Concerns about exposing participants to diseases in order to study treatment efficacy.

Key Definitions in Epidemiology

  • Morbidity: State of being diseased or unwell.

  • Morbidity Rate: The frequency of a given disease in a population, typically per 1,000 individuals.

  • Prevalence: Proportion of individuals in a population who have a certain disease at a specific time.

  • Mortality: The incidence of death within a population due to a specific cause.

    • Emphasis on differentiation between morbidity and prevalence rates.

Population Studies and Disease Tracking

  • The example of testing for COVID-19 prevalence at UC Davis as means to track infection versus sickness levels.

  • Understanding of sporadic, endemic, and pandemic disease spread.

  • Discussion of environmental factors affecting disease transmission, including geographical patterns.

  • Importance of ongoing health communication and vaccine efficacy discussions given global health challenges.