#6 Health_and_Disease_Types-Causes

Health and Disease Types & Causes

Page 1

Course Information
  • Course Code: NST 1070


Page 2

Outline of Topics
  1. Health

  2. Types of Diseases

  3. Environmental Justice

  4. Direct Health Impacts of Climate Change

  5. Case Study – Lyme Disease


Page 3

Health
  • Definition by the WHO:
    The World Health Organization (WHO) defines health as a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity.

  • The WHO's Declaration of Alma-Ata (1978):
    This declaration emphasized more attainable goals, such as enabling people to achieve health which allows them to lead productive lives.


Page 4

Disease
  • Definition of Disease:
    A condition that affects the structure or function of all or some parts of an organism that is not immediately due to an internal injury; diseases typically have distinct signs and symptoms.


Page 5

Human Infectious Diseases and Their Causative Agents
  • Viruses:
    Examples include:

    • COVID-19

    • Influenza

    • Urinary Tract Infections (UTIs)

    • HIV

    • Hepatitis

    • Ebola

    • Dengue

  • Bacteria:
    Examples include:

    • Tuberculosis

    • Cholera

    • UTIs

  • Fungi:
    Examples include:

    • Athlete's foot

    • Candidiasis

    • Ringworm

    • Fungal pneumonia

  • Parasites:
    Examples include:

    • Malaria

    • Toxoplasmosis

    • Scabies


Page 6

Difference Between a Bacteria and a Virus
  • Contagiousness of Viral Illnesses:
    Viral illnesses are generally considered more contagious than bacterial infections. This is due to their smaller size and capability to spread easily through the air or by other means.


Page 7

Examples of Diseases
  • Viral Diseases:

  • Chickenpox

  • HIV/AIDS

  • Influenza

  • COVID-19

  • Bacterial Diseases:

  • Strep Throat

  • Urinary Tract Infection (UTI)

  • Tuberculosis

  • Whooping Cough


Page 8

Therapeutic Antibiotics
  • Considerations in Antibiotic Usage:

    • Usage can be measured in therapeutic indices, which reflects how antibiotic treatments interact with pathogens.


Page 9

Antibiotic Resistance
  • Definition of Antibiotic Resistance:
    A phenomenon in which a portion of bacteria survives antibiotic treatment, leading to the development of resistant pathogens.

  • Mechanism of Resistance Spread:

    1. Bacteria transfer resistance traits to other bacteria.

    2. Antibiotics kill susceptible pathogens, leaving behind resistant strains, which can proliferate freely.


Page 10

Pathways of Antibiotic Resistance Spread
  1. Antibiotic use in animals leads to resistant bacteria.

  2. Humans taking antibiotics develop resistant bacteria.

  3. Contaminated fertilizer or water can spread resistant bacteria to food crops.

  4. Drug-resistant bacteria can persist on meat, spreading when not handled or cooked properly.

  5. Resistant bacteria can remain in environments like hospitals, facilitating transmission between patients.


Page 11

Global Deaths from Infectious Disease Syndromes Due to Antimicrobial Resistance (2021 Data)
  • Annual Statistical Breakdown:

    • Attributed to antimicrobial resistance:

    • Lower respiratory infections: 3.15 million

    • Bloodstream infections: 397,000

    • Diarrhea: 1.17 million

    • Tuberculosis: 1.13 million

    • Abdominal infections: 567,000

    • Kidney and urinary tract infections: 421,000

    • Skin infections: 327,000

    • Meningitis: 225,000

    • Typhoid and paratyphoid: 170,000

    • Endocarditis: 105,000

    • Bone and joint infections: 24,500

Note: It's estimated that at least 456,000 deaths from bloodstream infections could have been prevented if they weren't resistant to antimicrobials.


Page 12

Prevention Strategies
  • Vaccines are critical for preventing diseases.

  • Infection can be cleared with antibodies, which can result in a polyclonal response targeting multiple pathogens, reducing the emergence of escape mutants.


Page 13

Antibodies Explained
  • Antibodies are proteins produced by the immune system in response to antigens presented by pathogens.

  • Antigenic Variation: Viruses can mutate over time, creating challenges for immune recognition.


Page 14

Reasons for Viral Mutation
  • Purpose of Mutations in Viruses:

    • To reproduce faster

    • To adhere better to host cell surfaces

    • To evade immune systems and vaccines.


Page 15

Immune Response to New Pathogens
  • When a new pathogen introduces a unique antigen, the body must produce specific antibodies to combat the infection.


Page 16

Good Bacteria and the Human Microbiome
  • Human Genome and Bacterial Genes:

    • Human genome: ~20,000 genes

    • Estimated bacterial genes: ~3 million genes (bacteria outnumber human cells significantly).

  • Previous assumptions stated there were 10 bacterial cells for every human cell, leading to a significant body weight proportion attributed to bacteria.


Page 17

Types of Diseases – Common Comparisons
  1. Acute vs Chronic Diseases:

    • Acute: Short duration, rapid onset (days/weeks)

    • Chronic: Long duration, gradual onset (months/years)


Page 18

Differences between Acute and Chronic Diseases

Characteristics

Acute Disease

Chronic Disease

Onset

Sudden

Gradual

Cure

Usual

Rare

Course

Short

Lengthy

Patient Role

Passive

Active, includes caregiver

Physician Role

Dominant

Team care, patient included

Return to Normal Likelihood

Likely

Unlikely

Future Uncertainty

Rare

Common


Page 19

Examples of Acute and Chronic Diseases
  • Acute Diseases:

    • Broken Bone

    • Asthma Attack

    • Tonsillitis

    • Chickenpox

  • Chronic Diseases:

    • Diabetes

    • Osteoporosis

    • Heart Disease

    • Arthritis


Page 20

Types of Diseases – Common Comparisons (Cont.)
  • Infectious/Pathogenic vs Non-Infectious/Non-Pathogenic:

    • Infectious Diseases: Caused by pathogens like bacteria or viruses.

    • Non-Infectious Diseases: May be due to genetics, anatomy, age, or environmental factors, and can be influenced by social determinants of health.


Page 21

Disease Agents
  • Non-infectious Diseases (Abiotic):

    • Examples include nutrient deficiencies, water stress, temperature stress, chemical injury, pollution.

  • Infectious Diseases (Biotic or Pathogens):

    • Examples include fungi, bacteria, nematodes, viruses, etc.


Page 22

Examples of Infectious and Non-Infectious Diseases
  • Infectious Diseases:

    • COVID-19

    • HIV/AIDS

    • Chickenpox and shingles

    • Measles

    • West Nile Virus

  • Non-Infectious Diseases:

    • Cardiovascular Disease

    • Chronic Respiratory Disease

    • Diabetes

    • Parkinson's Disease


Page 23

Types of Diseases – Common Comparisons (Cont.)
  • Contagious/Communicable vs Non-Contagious/Non-Communicable:

    • Contagious Diseases: Spread from human to human.

    • Non-Contagious Diseases: Cannot be spread between humans.


Page 24

Communicable and Non-Communicable Diseases Examples
  • Communicable Diseases:

    • Measles

    • HIV

    • Strep Throat

    • Salmonella

  • Non-Communicable Diseases:

    • Cancer

    • Diabetes

    • Congestive Heart Failure

    • Alzheimer's Disease


Page 26

Types of Diseases – Common Comparisons (Cont.)
  • Zoonotic vs Vector-Borne:

    • Zoonotic Diseases: Spread from animals to humans or vice versa.

    • Vector-Borne Diseases: Transmitted by a bite from a host organism.

    • All vector-borne diseases are considered zoonotic.


Page 28

Examples of Zoonotic and Vector-Borne Diseases
  • Zoonotic Diseases:

    • Rabies

    • Avian Flu

    • Cat Scratch Disease

    • Hoof and Mouth Disease (FMD)

  • Vector-Borne Diseases:

    • Dengue Fever

    • Lyme Disease

    • Malaria

    • West Nile Virus


Page 33

Methods of Disease Transmission
  1. Direct Transmission:

    • Disease is passed directly from one infected person or animal to another.

  2. Indirect Transmission:

    • Disease is transmitted without direct contact.

  3. Vector Transmission:

    • Requires another organism to transfer disease.

  4. Person-to-Person:

    • Occurs through touch or exchange of body fluids.

  5. Droplet:

    • Spread by coughing or sneezing, causing infectious droplets to land nearby.

  6. Fecal-Oral:

    • Transmitted via microscopic fecal matter reaching the mouth.

  7. Airborne:

    • Spread through the air from an infected individual’s respiratory actions.

  8. Fomites:

    • Inanimate objects can transmit disease, such as contaminated surfaces or water fountains.

  9. Insect Bite:

    • Common method is through vectors like mosquitoes.


Page 34

Climate Change and Disease Transmission
  • Increased Transmission Risks:

    • Climate change will elevate the risk of vector transmission pathways.

    • Aquatic environments may foster the growth of infectious diseases, leading to increased spread.


Page 35

Health Impacts of Climate Change
  • Air Pollution & Allergens:

    • Associated with increases in asthma, allergies, and cardiovascular diseases.

  • Extreme Heat:

    • Results in heat-related illness and increased mortality rates.

  • Drought:

    • Affects water supply, leads to health conditions like Valley Fever.

  • Food System Impacts:

    • Contributes to malnutrition, food insecurity, and foodborne illnesses.

  • Extreme Weather:

    • Elevates risks of injuries and fatalities due to natural disasters.


Page 37

Research on Climate Change and Infectious Diseases
  • A recent review published in August 2022 indicated that climate change has aggravated 218 of the 375 known infectious diseases, amounting to a 58% increase.

  • When non-infectious diseases, like asthma, are included, the number rises to 277, representing 74% of diseases affected.


Page 41

Vulnerability to Climate Change
  • Exposure: Physical contact with biological, chemical, or psychosocial stressors affected by climate change.

  • Sensitivity: Degree to which communities are affected by climate change impacts.

  • Adaptive Capacity: Ability to adjust to climate-related hazards.

  • Health Outcomes: These can include injuries, chronic illness, developmental issues, and mortality.


Page 42

Factors Driving Vulnerability to Climate Change
  • Low-income populations may suffer more significantly from climate change due to socioeconomic obstacles.

  • Certain demographics, like pregnant women or children, possess heightened sensitivity to climate risks, while certain locations are predisposed to specific climate threats.

  • Age and disability can limit the ability to adapt to climate change.


Page 44

Lyme Disease Overview
  • Definition and Characteristics:
    Lyme disease is a bacterial infection caused by Borrelia burgdorferi, transmitted to humans through tick bites. It is classified as both acute and chronic, infectious, zoonotic, vector-borne, and non-communicable.

  • Outbreaks:
    The disease was named after Lyme, Connecticut, where initial attention arose due to an outbreak of arthritis cases.

  • Incidence: In 2023, CDC reported over 89,000 cases of Lyme disease in the U.S.


Page 46

Symptoms of Lyme Disease
  • Lyme disease progresses through three stages, each characterized by specific symptoms, which can evolve without treatment:

    1. Early Localized Stage: Symptoms may include skin rash, headaches, flu-like symptoms, fatigue, and swollen lymph nodes.

    2. Disseminated Stage: Symptoms can include multiple rashes, heart palpitations, severe joint pain, memory issues, and neurological symptoms.

    3. Late Disseminated Stage: Characterized by joint problems, neurological issues, chronic fatigue, and mood disorders.

    • Notably, over 30% of patients may not present the characteristic skin rash associated with Lyme disease.


Page 47

Lyme Disease Lifecycle
  • Infectious Agent: Borrelia burgdorferi

  • Vector: Blacklegged ticks (Ixodes scapularis or Ixodes pacificus)

  • Reservoir Hosts: Includes ground-dwelling birds and mammals, especially white-footed mice.

  • Incidental Hosts: Humans and dogs.

  • Transport Mechanism: Primarily through white-tailed deer for tick reproduction.


Page 49

Ideal Conditions for Lyme Disease Transmission
  • Ticks thrive in warm and humid environments, most active when temperatures exceed 45°F (7°C).

  • Warmer winters contribute to survival rates of both ticks and their rodent hosts, enhancing the likelihood of disease spread.


Page 50

Geographic Range of Ticks
  • Changes in the geographic distribution of blacklegged ticks in the United States have been documented and are vital to public health monitoring.


Page 54

Class Activity Instructions
  • Form groups of ~4 students, each assigned a disease to characterize, find statistics, and analyze risk factors using terms and concepts covered in class.

  • Selected diseases for group work include Malaria, Tuberculosis (TB), Zika Virus, Cholera, and Heat-Related Illness.


Page 55

Reminders
  • Homework: HW #2 posted and due on 9/22.

  • Reading Check: RC #4 due on 9/17.