PUBH Exam 3 Study

Infectious

Disease caused by different classes of pathogenic organisms commonly called germs

Non-infectious

Any disease not caused by a pathogen (asthma, CVD, obesity)

Infectious diseases

Leading cause of death worldwide, particularly in low-income countries, especially in young children

• > 650K deaths associated with respiratory diseases from the flu

• > 1.2 million deaths from diarrheal disease

  • > 390K deaths were children under 5 years old in 2021

• >136K deaths from measles in 2022

Although the U.S. have “eliminated” some diseases…

Infectious ones still are a major PH problem because they can spread from person to person, threatening the health of entire communities and countries, not just individuals

Zoonotic

Diseases caused by infectious agents that can be transmitted between animals & humans

“Emerging” infectious diseases, many from animals

One Health

“Achieving optimal health outcomes recognizing the interconnection between people, animals, plants, & their shared environment”

Types of Diseases:

Communicable & Contagious

Communicable disease

An infectious disease that may be passed from individual to individual

• Infectious & communicable disease do not have the same meaning

• Communicable is infectious that is easily spread from one species to another

• All communicable diseases are infectious diseases, but not all infectious diseases are communicable

Contagious disease

A very communicable disease, i.e., an infectious disease that very readily spreads from person to person

Types of Agents:

Bacteria, Viruses, Fungi, Protozoa, Helminths

Bacteria

One-cell microorganism that multiply quickly & may release chemicals which can make you sick (e.g., TB, tetanus, cholera, whooping cough)

Viruses

Capsules that contain genetic material & use your own cells to multiply (e.g., flu, HIV)

Fungi

Primitive vegetables, like mushrooms, mold, yeasts (e.g., Histoplasmosis, athlete’s foot)

Protozoa

One-celled animals that use other living things for food & a place to live (e.g., malaria, toxoplasmosis)

Helminths

Parasitic worms that cause disease & illness in humans (e.g., tapeworm, pinworm, & roundworm)

Hosts (Reservoirs)

Non-vector: Humans, other vertebrates, birds, bats

Vector: Asymptomatic carriers of pathogen, mosquitoes, ticks, flies

Routes of Transmission:

Mouth & nose, eyes, skin, digestive tract, genitals & urinary tract

Direct Transmission

Skin to skin (Herpes type 1), Mucous to mucous (STIs), Across placenta (Rubella, HIV), Sneeze-cough/Aerosolized from person to person (Influenza, TB)

Indirect Transmission

Food-borne (Salmonella), Water-borne (Cholera), Vector-borne (Malaria), Air-borne from person to object (Chickenpox, colds)

Environmental Factors:

• Land use (de/reforestation, outdoor activities)

• Infrastructure (air filtration, access to clean water)

• Changes in food production & handling

• Increased use of immunosuppressive/antibiotics

• Ownership of exotic pets/interaction with animals

The “Epi” Triad

Agent, Host, Environment

Why can some diseases be “eliminated” & not others?

• Type of reservoir

• Ability to live outside of humans

• “Carrier state” – Host shows symptoms

• Disease produces long-term immunity

Control Measures

• Water treatment

• Vector control

• Rodent reduction

Isolation

Separates sick people with a contagious disease from people who are not sick

Quarantine

Separates & restricts the movement of people who were exposed to a contagious disease to see if they become sick

Immunizations

Introduces antibodies (injection, nasal) to stimulate immune system to produce own antibodies

Vaccine types:

• Live-attenuated vaccines (MMR, chicken pox)

• Inactivated (dead) vaccines (Flu, polio)

• Subunit, recombinant, polysaccharide, & conjugate vaccines (HPV, Whooping Cough)

• Toxoid vaccines (Diphtheria, Tetanus)

Herd immunity

Concept of protecting a community against certain diseases by having a high % of the community’s population immunized

• Vary in terms of effectiveness, age is a factor

Screening & Treatment

• Case finding - Confidential interviewing of those to see who may be exposed

• Treating “contacts” - Essential for control & prevention of infectious disease

Personal Prevention Tips/Micro Strategies for Communicable Diseases

• Washing your hands is one of the most important steps to avoid getting sick & spreading germs to others

• Personal Protective Equipment (PPE)

• Get immunized

• Take care of your immune system (sleep, healthy diet, physical activity, manage stress)

• Protect yourself around others who are sick

WHO Priority Diseases

Diseases pose the greatest public health risk due to their epidemic potential and/or there are no or insufficient countermeasures

Urgent need for accelerated R&D for:

Covid-19, Ebola, Lassa fever, Zika, Nipah, Middle East respiratory syndrome coronavirus (MERS-CoV) & Severe Acute Respiratory Syndrome (SARS), Rift Valley fever, Crimean-Congo hemorrhagic fever

2014 Ebola Outbreak

Primarily affected three countries in West Africa (Guinea, Liberia, Sierra Leone)

• Approximately 28,504 cases and 11,298 deaths

• 4 patients treated for Ebola in the US, one died in October 2014; two of the survivors treated the patient in TX who died

SARS (Severe Acute Respiratory Syndrome)

• Caused by a corona virus most likely of animal origin

• Spread by large respiratory droplets from sneezing & coughing

• Hong Kong, 2003: “index case” infected hundreds in hotel→worldwide-8,096 infected, 744 died

Disease X

• Stands for the unknown

• Represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease

Infectious Diseases of On-going Concern

Diseases like STIs, Dengue, yellow fever, HIV/AIDS, tuberculosis, malaria, influenza causing severe human disease, smallpox, cholera, etc, continue to pose major PH problems & further R&D is needed through existing major disease control initiatives, extensive R&D pipelines, existing funding streams, or established regulatory pathways for improved interventions

Influenza (the “flu”)

• Contagious respiratory illness caused by influenza viruses

• It can cause mild to severe illness

• Risk varies by age & other conditions

• There are Type A & B

• Get vaccinated each year to prevent it

Spillover - Zika, Ebola & Beyond

Host: Human behaviors (consuming contaminated date palm sap in the case of Nipah, or funerary practices in the case of Ebola) create the crucial contact point for the virus to "spill over." Health status & demographics (age/sex) are shown to affect who is most vulnerable, such as pregnant women and Zika

Environment: Human changes to the environment—such as deforestation, urbanization, & farming—push animal hosts closer to human settlements, creating new points of contact. Geography & global travel networks are shown to allow an epidemic (Ebola in West Africa) to rapidly spread into an international crisis

Environmental Health Concepts

The science & practice of preventing human injury & illness & promoting well-being by:

• Identifying & evaluating environmental sources & hazardous agents

• Limiting exposures to hazardous physical, chemical, & biological agents in air, water, food, etc, that may adversely affect human health

Healthy People 2030 - Promoting healthier environments to improve health 

• Reducing exposure to arsenic, lead, mercury in children, bisphenol A, perchlorate

• Increasing the proportion of people whose water supply meets Safe Drinking Water Act regulations

• Reducing health & environment risks from hazardous sites

Toxicology

• The study of the effects of poisons & the foundation of environmental health

• Arguably the oldest scientific discipline (earliest humans had to know which plants were safe to eat)

• Application of science to important environmental & PH issues, understanding HOW something (poison) produces a toxic effect

Fundamental Rules

• Exposure must occur for the chemical (toxin) to present a risk

• Magnitude of risk is proportional to the potency of the chemical & the extent of the exposure

Routes of Exposure

• Absorption through skin

• Injection (bite, cut)

• Inhalation (air via nose)

• Ingestion (mouth)

• Mucosal membranes (nose, eyes)

Different toxic response arise from different:

• Routes, frequencies, & duration of exposure

• How the body metabolizes “toxin” is key & highly variable from individual-to-individual

• Depending on the persons’ life stage, sex, metabolism, excretion, nutritional status, health of the individual, presence of other chemicals

Types of Toxic Effects

• Death

• Organ Damage (CNS, skin, eyes, reproductive, immune, liver, respiratory)

• Mutagenesis (changing DNA)

  • Genetic make-up - Some diseases are the result of an interaction between our genetics & chemical in our environment

• Carcinogenesis (cancer causing, cell changes, tumor growths)

• Teratogenesis (birth defects)

Sources of Toxins:

Environmental, Occupational, Therapeutic, Dietary, Accidental, Household, Nature, Deliberate (used as a weapon)

Occupational Health

• Looking for exposures at work & safety concerns

• Health effects & diseases associated with specific jobs, often by members of lowest social class, not always viewed as a societal concern

“Radium Girls” 1920s Ottawa (IL) Radium Dial Company

• Radium dial painters “aniline dye” workers; painters licked their brushes to pull it to a point

• The owners of the company knew of the effects of handling radium, yet exposed women to deathly danger

Occupations with higher risks:

Chemical industries, healthcare workers, pharm lab work, rubber & furniture manufacturing, pesticides/exterminator

Rachel Carson (1907-1964)

• American writer, scientist, ecologist

• Known as the founder of our contemporary environmental movement

• Questioned pesticide practices; took on the industry & warned of the dangers of chemical pesticides, sparking a nationwide ban on DDT & other pesticides

Rachel Carson helped lead the National Environmental Policy Act (NEPA), 1969

A national policy “to create & maintain conditions under which humans & nature can exist in productive harmony, that permit fulfilling the social, economic & other requirements of present & future generations.”

Independent Study: Malaria

1. The public health problem of malaria is death by weak immune systems

2. Malaria drains a country’s workforce, impairs cognitive development, consumes up to 40% of a country’s public health spending, children under 5 accounted for about 76% of all malaria deaths

3. Prevention Strategy: Insecticide-treated nets, form of vector control, a physical barrier protecting people from mosquito bites while they sleep

Independent Study: Tuberculosis

1. The public health problem is death by airborne disease

2. ¼ of the world’s population is estimated to be infected with TB bacterium, but they are not yet sick & cannot transmit it. People with HIV are 16 to 27 times more likely to get TB. Even with a cure, millions of people with TB are “missed” by health systems every year.

3. Prevention Strategy: Treatment of Latent TB Infection (LTBI), latent TB is when someone has TB bacterium but aren’t sick so identifying these people early, giving them a shorter, preventive course of medicine, can kill the bacteria but can require 3-9 months of antibiotics.

Independent Study: Birth Control Access

1. The public health problem is death by maternal mortality

2. Higher rates of unintended pregnancies can lead to maternal deaths, unsafe abortions, & adverse outcomes for the child causing infant mortality. “Contraceptive deserts” where there is a lack of geographic access to a health clinic that offers full range birth control methods

3. Prevention Strategy: Increasing access to & awareness of Long-Acting Reversible Contraception (LARC) such as IUDs & implants, with a failure rate of less than 1%. LARC methods work continuously without any action needed from the user

Intro to Health Promotion

Stats or numbers (rates) are not always enough, especially when considering determinants

Individual & Community Assessments need to:

• Identify assets & barriers

• Examine the “bigger” picture – “data” (rates, ranks) do not tell the whole story

• What’s contributing to the determinants?

• Does the “priority population” think the determinant/prevention program is important?

Qualitative Concepts:

• Takes systematic approach

• Express in words, images

• Determinants & public health problems are complex

How do you collect qualitative data?:

• Interviews

• Focus groups

• Case studies

• Community meeting

• Systematic observation (field notes)

Uses of Qualitative Methods In PH:

• Needs & assets assessments (program planning)

• Learning about priority populations (program participants’ knowledge, attitudes, beliefs)

• Evaluating problems/prevention strategies

Health Promotion

The combination of educational & environmental supports for actions & living conducive to health

• Broader than health education

• Purposeful, organized

• Involves a planned approach/program/intervention (macro)

Framework for Health Promotion

Health promotion represents a mediating strategy between people & their environments, synthesizing personal choice & social responsibility in health

Health Education

Any combination of learning experiences designed to facilitate voluntary actions (behavior) conducive to health

• Usually embedded in promotion programs

• One tool or strategy

Focuses on individuals (micro)

Health Education Philosophies

• Behavior change

• Cognitive-based learning (knowledge, skills)

• Decision-making & functioning (attitudes, beliefs, self-efficacy)

Assumptions of Health Promotion

1. Health status can be changed

2. Disease occurrence can be understood

3. Prevention strategies can be developed for health problems

4. Health is affected by multiple factors – not just lifestyle

5. Changes in micro & macro level behaviors & factors can positively affect health

6. People & communities can assume responsibility for their health

7. Individual responsibility doesn’t mean victim blaming

8. For permanent behavior change, people must be ready & motivated

Comparison of Health Promotion & Health Education