PBH 110.1 Midterm Exam Review Guide

For Intro & Origins of Public Health

Three Core Functions of Public Health

• Assessment – Systematic collection, analysis, and dissemination of information about the health of a community.

  • Example: Conducting surveillance on disease outbreaks like COVID-19 to track infection rates.

• Policy Development – Using data to create public health policies and strategies that improve community health.

  • Example: Implementing regulations on tobacco sales to reduce smoking rates.

• Assurance – Ensuring that essential health services are accessible and high quality.

  • Example: Providing vaccination programs to underserved populations.

5 Public Health Disciplines

• Epidemiology – Studies the patterns and causes of diseases in populations.

  • Example: Investigating an E. coli outbreak in a restaurant.

• Biostatistics – Uses statistical methods to analyze public health data.

  • Example: Calculating the effectiveness of a new vaccine.

• Environmental Health Sciences – Examines how environmental factors affect health.

  • Example: Testing water sources for lead contamination.

• Health Policy and Management – Focuses on healthcare systems, policies, and access to care.

  • Example: Evaluating the impact of Medicaid expansion on healthcare access.

• Social and Behavioral Sciences – Studies how behaviors and social structures affect health.

  • Example: Designing anti-smoking campaigns to encourage smoking cessation.

How the Plague Spread to Become the Deadliest Disease:

• The Black Plague (Bubonic Plague), caused by the Yersinia pestis bacteria, spread through fleas carried by rats and human-to-human transmission in its pneumonic form.

Factors that Contributed to Its Spread:

• Trade Routes – The disease spread via Silk Road trade and merchant ships, reaching Europe from Asia.

• Poor Sanitation – Overcrowded, filthy cities allowed rats and fleas to thrive.

• Lack of Medical Knowledge – People did not understand germs or proper quarantine procedures.

• Social Disruptions – Wars and famine weakened populations, making them more susceptible.

• Human-to-Human Transmission – In its pneumonic form, the disease spread through coughing and sneezing (airborne transmission).

Key Factors That Increased Spread & Fatality in Philadelphia:

• Delayed Response – Despite warnings, officials did not take early action to close public spaces.

• Mass Gatherings – A large parade on September 28, 1918, attended by 200,000 people, accelerated the outbreak.

• Overcrowding & Poor Sanitation – The city had cramped living conditions that facilitated person-to-person spread.

• Lack of Medical Resources – Hospitals were overwhelmed, with a severe shortage of doctors and nurses due to World War I.

• Censorship & Misinformation – Authorities downplayed the severity of the flu to maintain morale during wartime, preventing proper public health measures.

Public Health Challenges & Solutions During the Industrial Revolution

Problem: Poor Sanitation & Contaminated Water

• Overcrowded cities lacked proper sewage systems, leading to contaminated drinking water and deadly outbreaks of cholera and typhoid.

• Solution:

  • Development of modern sanitation systems (sewage and water filtration).

  • The Public Health Act of 1848 (UK) created local health boards to oversee sanitation.

  • John Snow’s cholera investigation (1854) proved contaminated water was the cause, leading to safer water policies.

Problem: Air Pollution & Occupational Hazards

• Factories emitted toxic fumes (coal smoke, chemical pollutants), leading to respiratory diseases (e.g., bronchitis, tuberculosis).

• Dangerous factory conditions resulted in high injury and death rates among workers.

• Solution:

  • Factory Acts (1833, 1847, 1864, etc.) established workplace safety regulations and limited child labor.

  • Introduction of air pollution regulations and improved ventilation in workplaces.

  • The creation of labor unions pushed for better working conditions and shorter hours.

First major public health legislation

• 1847, UK

• Sparked by severe cholera outbreaks and worsening urban health conditions during the Industrial Revolution

Who Was Mary Mallon?

• Mary Mallon (1869–1938), also known as "Typhoid Mary," was an Irish-born cook in the United States who became the first known asymptomatic carrier of typhoid fever. Despite appearing healthy, she unknowingly spread the disease to numerous people.

• Preventative actions made from this case

  • Public Health Investigation & Identification

  • Forced Quarantine

  • Advancing Disease Carrier Awareness

Tuskee Study

• Lack of informed consent: The men were never fully informed about the nature of the study, and they were misled into thinking they were receiving treatment for bad blood

• Denial of treatment: Even after the development of penicillin as an effective treatment for syphilis in the 1940s, the men were deliberately denied access to it.

Belmont Report

• Was published in 1979 to guide ethical research practices, it outlines three core ethical principles

  • Respect for persons: This principle includes acknowledging autonomy and the need to obtain informed consent from participants.

  • Beneficence: Researchers must minimize harm and maximize potential benefits to participants.

  • Justice: The benefits and burdens of research should be distributed fairly, ensuring no group is unfairly burdened or excluded from the benefits of research.

Chain of Infection

• Reservoir/Host: The source where the pathogen lives and multiplies (e.g., human, animal, environment).

• Mode of Transmission: How the pathogen moves from one host to another (e.g., direct contact, airborne, vectors).

• How to disrupt the chain

  • Eliminate the Reservoir: Kill or remove the source of infection (e.g., cleaning contaminated surfaces, treating infected individuals).

  • Interrupt the Mode of Transmission: Use protective barriers (e.g., masks, handwashing, sterilization), ensure proper hygiene, and implement quarantine measures when necessary.

  • Increase Immunity: Boost individual or community resistance through vaccination or antiviral medications.

  • Control Vectors: For diseases spread by insects or animals (like malaria or Lyme disease), control or eliminate the vector (e.g., mosquito nets, pesticides, or rodent control).

Healthy People 2020

• The initiative aimed to improve public health by setting specific, measurable targets in areas such as disease prevention, health equity, mental health, and healthcare access. It was designed to serve as a framework for national, state, and local efforts in addressing major public health challenges.

  • Comprehensive Health Goals: It addressed broad health issues, including chronic diseases, environmental health, mental health, substance use, and health equity.

  • Targeted Objectives: For each health area, specific, evidence-based objectives were set. For example, reducing obesity rates or increasing access to mental health services.

  • Focus on Health Disparities: Healthy People 2020 emphasized reducing health disparities across different populations, including racial, ethnic, and socioeconomic groups.

• How Healthy People 2020 Goals Are Developed

  • Stakeholder Input: Involved input from public health experts, researchers, advocacy groups, and the public.

  • Data Collection and Analysis: Data from national health surveys and research studies are used to identify priority health issues.

  • Evidence-Based Approach: The goals are based on scientific evidence and public health research that show effective ways to address health problems.

  • Public Comment and Review: A draft of the objectives is often made available for public comment and reviewed by experts.

The 5-Step Process in the Public Health Approach

• Define the health problem:

  • This involves identifying and understanding the specific health issue and its impact on the population.

  • Example: Obesity in children. Data shows that childhood obesity rates are increasing in certain regions, leading to an increased risk of chronic diseases like diabetes and heart disease.

• Identify risk factors:

  • In this step, you determine the factors or behaviors that contribute to the health problem.

  • Example: For childhood obesity, risk factors could include poor diet, lack of physical activity, socioeconomic factors, and limited access to healthy foods in certain communities.

• Develop and test interventions:

  • This involves designing programs or strategies to address the risk factors and solve the health problem, followed by testing them to determine their effectiveness.

  • Example: A school-based intervention where children are provided with healthier meal options and daily physical activity programs. Testing could involve a pilot program in select schools to measure effectiveness in reducing obesity rates.

• Implement interventions:

  • Once an intervention is tested and proven effective, it is implemented on a larger scale.

  • Example: After testing, the school-based intervention is rolled out to multiple schools in a region, and community outreach is done to ensure families are involved in promoting healthier lifestyles.

• Evaluate the results:

  • Evaluation involves assessing whether the intervention was successful in achieving its goals, and whether any adjustments are needed.

  • Example: After a year of implementing the school program, public health officials assess whether childhood obesity rates have decreased. They might collect data on children's body mass index (BMI), review feedback from schools, and determine if further changes (e.g., expanding access to physical activity or nutrition education) are necessary.

Who are the 4 H’s of HIV/AIDS epidemic

• Homosexuals (or Men who have Sex with Men - MSM): This group has historically had the highest rates of HIV transmission due to higher rates of unprotected anal sex, which carries a higher risk for HIV transmission compared to other sexual practices.

• Hemophiliacs: People with hemophilia, a condition that impairs blood clotting, were at risk in the early years due to the use of contaminated blood products. Prior to screening blood donations for HIV, some individuals with hemophilia contracted HIV through transfusions.

• Heroin Users (Injection Drug Users): People who inject drugs are at increased risk for HIV due to the sharing of needles and drug paraphernalia, which can transmit the virus through blood-to-blood contact.

• Haitians: Early on in the epidemic, Haitian Americans were identified as a population with an elevated risk of HIV, mainly due to the higher prevalence of HIV in Haiti, where the virus was more common. However, over time, the focus on the Haitian population was reevaluated, and the risk factors tied to behavior rather than nationality were emphasized.

- Know that in defining health, the World Health Organization includes the concept of wellbeing (physical, mental and social well-being), not merely the absence of disease or infirmity

- Understand the Levels of prevention and speak to which levels medicine addresses and which public health addresses

For Epidemiology

The Story of John Snow (the father of epidemiology)

• In the mid-1800s, cholera was a deadly disease spreading through London, and it was believed to be caused by "miasma" (bad air). However, John Snow suspected that the disease was actually transmitted through contaminated water.

• Snows Key Work

  • Mapping the Cholera Cases:

    • In 1854, there was a major outbreak of cholera in the Soho district of London. Snow meticulously mapped the locations of the cholera cases, plotting them on a map of the area. This spatial analysis revealed that the majority of cases clustered around a specific public water pump on Broad Street (now Broadwick Street).

  • Investigating the Source of Contamination:

    • Snow hypothesized that the source of the outbreak was the water from the Broad Street pump. He carefully examined the residents who had contracted cholera and found that many of them had used the pump for drinking water. Conversely, people who drank water from other sources, such as water carriers from a different pump, were much less likely to contract the disease.

  • Removing the Pump Handle:

    • As a result of his findings, Snow convinced the local authorities to remove the handle of the Broad Street pump, thus preventing people from using contaminated water. Shortly after the pump was disabled, the cholera outbreak began to subside, providing strong evidence that contaminated water was indeed the cause of the disease.

Key Components of a Case and Case Definition:

Case, A case is any individual who meets the criteria for the disease or condition being investigated during the outbreak.

• Confirmed Case: A person who has been diagnosed with the disease based on laboratory tests, clinical diagnosis, or other scientific evidence.

• Probable Case: A person who shows symptoms or signs of the disease but may not yet have confirmed laboratory results.

• Suspected Case: A person who exhibits symptoms or has been exposed to the disease but has not yet been diagnosed.

Case Definition, A case definition is a set of standardized criteria used to classify and count cases during an outbreak. It typically includes:

• Clinical criteria: The specific signs and symptoms that define the disease (e.g., fever, rash, gastrointestinal distress).

• Laboratory criteria: If applicable, the laboratory test results needed to confirm the presence of the pathogen or disease (e.g., blood tests, stool samples).

• Epidemiological criteria: Exposure history, such as where the individual lives, where they have traveled, or whether they have had contact with other infected people.

Endemic

• Definition: A disease is considered endemic when it is consistently present in a particular population or geographic area over a long period of time. It occurs at a predictable, stable rate and is often part of the local environment or culture.

• Example: Malaria is endemic in many parts of Sub-Saharan Africa, where it is a common and ongoing health concern due to the presence of mosquito vectors and local conditions that support transmission.

Epidemic

• Definition: An epidemic refers to a sudden increase in the number of cases of a particular disease beyond what is normally expected in a population or geographic area. It typically involves a localized or regional surge in cases that surpasses the usual baseline.

• Example: An outbreak of measles in a community where it had previously been controlled or low in numbers, due to a lapse in vaccination rates or an introduction of the virus from outside the area.

Pandemic

• Definition: A pandemic is an epidemic that has spread across multiple countries or continents, affecting a large proportion of the global population. It typically involves a new or highly contagious infectious disease, and its spread may lead to widespread social, economic, and healthcare system impacts.

• Example: The COVID-19 outbreak, caused by the SARS-CoV-2 virus, was declared a pandemic in 2020 because it spread rapidly worldwide, causing infections in virtually every country.

Epidemiological Methods for Infectious Diseases:

• Epidemiology is crucial in managing and preventing infectious diseases because they are often caused by pathogens that can spread rapidly through populations. 

• Chronic diseases, such as heart disease, diabetes, and cancer, require a different approach due to their long-term, often non-contagious nature.

Circumstances when a disease requires Epidemiologic investigation

• Outbreaks of Infectious Diseases

• Unexplained Increase in Disease Incidence

• Epidemic or Pandemic Events

• Emergence of New or Novel Diseases

• Sporadic or Isolated Cases

• Detection of Unusual or Atypical Symptoms

• Bioterrorism or Intentional Release of Pathogens

Long-term epidemiological cohort studies

• Crucial for studying chronic diseases because they provide valuable insights into the development, risk factors, and prevention of these conditions over extended periods of time. These studies follow large groups of people (cohorts) over many years, collecting detailed data on various health indicators, behaviors, exposures, and genetic factors.

• Short comings of cohort studies

  • Biases and Confounding Variables

    • Selection bias: Cohort studies often involve participants who are healthier or more motivated to follow study protocols, which can skew the results.

    • Confounding variables: In long-term studies, many factors (e.g., genetics, socioeconomic status, access to healthcare) can influence the results, and it's challenging to control for all these potential confounders.

  • Loss to Follow-Up

    • One of the most significant challenges in cohort studies is loss to follow-up, where participants drop out of the study over time. This can lead to missing data, reducing the power of the study and introducing bias if those who drop out are systematically different from those who remain in the study

  • Time and Cost

    • Long-term cohort studies are expensive and require many years or even decades to produce meaningful results.

  • Changes in Population

    • Over long periods, societal factors, medical advances, and environmental changes can alter the characteristics of the population being studied

Death rates and life expectancy

• Death rates

  • Death rates measure the number of deaths in a specific population within a set period (usually one year)

• Life Expectancy

  • Life expectancy is the average number of years a person can expect to live

• Mortality rate

  • Mortality rate = (no. of deaths from cause) / (Total pop. at risk) * how many people are in the pop ur testing

Morbidity impacted by increased Longevity

• Refers to the incidence of disease or illness in a population, is impacted by increased longevity in the United States in several important ways. As life expectancy increases, people live longer, which can have both positive and negative effects on the overall morbidity rates.

  • While people are living longer, many are living with multiple health conditions that require ongoing management.

Incidence and Prevalence

Incidence

• Incidence refers to the number of new cases of a disease that develop in a specific population during a certain time period. It is used to measure the risk of contracting a disease within a specific timeframe

• Incidence helps assess the rate at which a new disease is occurring in a population, which can help in understanding the dynamics of an outbreak or the effectiveness of disease prevention measures.

  • Incidence Rate = (no. of new cases of disease in that time period) / (pop at risk during time) * People at risk

• Improved and more accessible screening = increased incidence, temporarily by detecting cases that would have otherwise gone undiagnosed.

Prevalence

• Prevalence refers to the total number of cases (both new and pre-existing) of a disease present in a population at a specific point in time or over a defined period.

• Prevalence is used to understand the overall disease burden in a population and to plan healthcare resources accordingly

  • Prevalence = (total no. new and existing) / (total pop at time) * how many people are in the pop ur testing

• Improved treatment = reduced prevalence, if it cures the disease more quickly or prevents death

What Are Notifiable Diseases?

• Notifiable diseases must be reported to public health authorities by healthcare providers, laboratories, or other officials. These diseases are tracked because they pose significant public health risks like outbreaks, epidemics, or potential bioterrorism threats.

Who notifies?

• Healthcare Providers (doctors, nurses, hospitals, clinics) – Report cases when they diagnose a notifiable disease.

• Laboratories – Report positive test results for certain diseases.

• Public Health Officials – Sometimes identify cases through surveillance programs

Who Gets Notified?

• Local Health Departments – First level of reporting, collects data within cities or counties.

• State Health Departments – Aggregates data and monitors disease trends.

• National Health Agencies (e.g., CDC in the U.S.) – Tracks diseases at the national level and provides guidance.

• Global Health Organizations (e.g., WHO) – For internationally significant diseases like Ebola or pandemic flu.

Intervention study vs Case-Control vs Cohort

Intervention study 

Case-Control

Cohort

• Lost-to-follow-up (also called attrition) occurs when participants in a study drop out or cannot be contacted before the study is completed. 

• You worry about this the most in cohort and intervention studies

For Biostatistics:

How to state null hypothesis

• Stating that there is no significance between the variables being studied

  • Ex. Research Topic: "Is smoking associated with lung cancer?"

    • H₀: There is no significant association between smoking and lung cancer.

Determining significance

• P-Value (Probability Value)

  • p < 0.05 = significant

• Confidence Intervals (CIs)

  • CI does not include the null value = significant

Why Are Screening Tests Used?

• Early Detection: Helps catch diseases in their early stages before symptoms appear, improving treatment outcomes.

• Preventative Care: Allows for interventions that may prevent the disease from progressing.

• Public Health Impact: Can reduce the burden of disease by identifying cases before they become severe or widespread.

Why are Diagnostic Tests Used?

• Confirm disease in symptomatic individuals or those with positive screening results

BRFSS (Behavioral Risk Factor Surveillance System)

• Purpose:

  • Tracks health-related behaviors, chronic diseases, and preventive measures in U.S. adults.

  • Focuses on risk factors for disease and health outcomes (e.g., smoking, obesity, physical activity).

• Data Collection Method:

  • Phone surveys (conducted by state health departments).

  • Self-reported data from adults (18+ years old).

  • Largest continuously conducted health survey in the world.

  • All use cross-sectional survey

NHANES (National Health and Nutrition Examination Survey)

• Purpose:

  • Measures health and nutrition status of children and adults.

  • Collects physical health data, including blood tests and medical exams.

• Data Collection Method:

  • In-person interviews (at home).

  • Physical examinations & lab tests (conducted in mobile health clinics).

  • Uses randomly selected participants to ensure a representative sample.

  • All use cross-sectional survey

NHIS (National Health Interview Survey)

• Purpose:

  • Collects broad health information on U.S. households, including access to healthcare, insurance, and chronic conditions.

• Data Collection Method:

  • Face-to-face household interviews.

  • Conducted by the U.S. Census Bureau.

  • Includes all age groups (children and adults).

  • All use cross-sectional survey

Crude Rates vs. Age-Adjusted Rates

• A crude rate is the total number of events (e.g., deaths, disease cases) in a population divided by the total population size, without considering differences in population structure (e.g., age distribution).

• Age adjusted rates are useful for  different populations, racial groups, trends over time

Years of Potential Life Lost (YPLL) and Its Use in Public Health

• YPLL= Predetermined Age − Age at Death

• Largest contributors are cancel and accidents

Risk Perception (How the Public Views Risk)

• Risk perception is how the general public interprets and emotionally responds to potential dangers

• Based on psychological, social, and cultural factors

•  While experts rely on data and statistical models, the public relies more on emotion, trust, and personal experience when evaluating risk.

  • Public health officials must bridge the gap between public perception and scientific evidence to ensure effective health policies 

Cost-Benefit Analysis (CBA) in Health Care: Which Is Easier to Calculate?

• Health care costs are generally easier to calculate than medical benefits

The Cencus

• A nationwide population count conducted every 10 years

• Provides critical demographic, economic, and social data used for government planning, policy-making, and resource allocation
  
  

Morbidity Compression Theory

• Developed by James Fries in 1980

• Theory suggests that as life expectancy increases, the period of illness and disability at the end of life can be compressed into a shorter timeframe

For Environmental Health:

Hazardous substances

Abestos

• Foubnd in old buildings

• Can cause lun disease 

• Being restriocted in countries

Lead

• Found in old paint, contaninated water, batteries

• Damages nervous system

• Regulations on paint, water filtration and bans in gasoline

Pesticides

• Agriculture, pest control

• Linked to cancer and enviormental harm

• Promtion of organic farming, restrictions on harmful pesticides

Rachel Carson’s’ Silent Spring

• A groundbreaking book that exposed the dangers of pesticides

Clean Water Act 1972 and the Safe Drinking Water Act 1974

Clean Water Act (CWA) – 1972

•  Reduced industrial pollution in waterways.

• Improved water quality in lakes and rivers.

• Increased enforcement against polluters.

• Protected wetlands and ecosystems.

Safe Drinking Water Act 1974

• Provided safer drinking water for millions of Americans.

• Reduced exposure to toxic chemicals in water.

• Established ongoing monitoring and enforcement for water suppliers.

• Strengthened public confidence in tap water safety.

Indoor air quality

• Detect pollutants and environmental conditions

  • Air Quality Sensors – Detect airborne particles, gases, and humidity levels.

  • Carbon Dioxide (CO₂) Monitors – Measure ventilation effectiveness.

  • Volatile Organic Compounds (VOC) Detectors – Identify chemical pollutants.

  • Humidity Meters – Assess moisture levels that can lead to mold growth.

USDA (United States Department of Agriculture)

• Regulates meat, poultry, and egg products, along with agriculture and nutrition programs

FDA (Food and Drug Administration)

• Regulates all other foods, drugs, medical devices, cosmetics, and dietary supplements

Flint Water Crisis

• Began in April 2014 when the city switched its water supply from Detroit’s system (Lake Huron) to the Flint River as a cost-saving measure. The new water source was highly corrosive, and due to improper water treatment, lead from aging pipes leached into the drinking water

Criteria Air Pollutants

• A group of six major air pollutants regulated by the EPA under the Clean Air Act due to their harmful effects on health and the environment

Greenhouse Gases (GHGs)

• Gases that trap heat in the Earth's atmosphere, leading to climate change.

Emergency Planning and Community Right-to-Know Act (EPCRA)

• A 1986 U.S. law that requires industries to report hazardous chemical storage and releases to the public

Non-Point Source Pollution

• Pollution that comes from multiple, diffuse sources rather than a single, identifiable site (like a factory or pipe)