#6 Health_and_Disease_Types-Causes
Health and Disease Types & Causes
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Course Information
Course Code: NST 1070
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Outline of Topics
Health
Types of Diseases
Environmental Justice
Direct Health Impacts of Climate Change
Case Study – Lyme Disease
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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.
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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.
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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
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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.
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Examples of Diseases
Viral Diseases:
Chickenpox
HIV/AIDS
Influenza
COVID-19
Bacterial Diseases:
Strep Throat
Urinary Tract Infection (UTI)
Tuberculosis
Whooping Cough
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Therapeutic Antibiotics
Considerations in Antibiotic Usage:
Usage can be measured in therapeutic indices, which reflects how antibiotic treatments interact with pathogens.
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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:
Bacteria transfer resistance traits to other bacteria.
Antibiotics kill susceptible pathogens, leaving behind resistant strains, which can proliferate freely.
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Pathways of Antibiotic Resistance Spread
Antibiotic use in animals leads to resistant bacteria.
Humans taking antibiotics develop resistant bacteria.
Contaminated fertilizer or water can spread resistant bacteria to food crops.
Drug-resistant bacteria can persist on meat, spreading when not handled or cooked properly.
Resistant bacteria can remain in environments like hospitals, facilitating transmission between patients.
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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.
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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.
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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.
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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.
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Immune Response to New Pathogens
When a new pathogen introduces a unique antigen, the body must produce specific antibodies to combat the infection.
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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.
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Types of Diseases – Common Comparisons
Acute vs Chronic Diseases:
Acute: Short duration, rapid onset (days/weeks)
Chronic: Long duration, gradual onset (months/years)
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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 |
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Examples of Acute and Chronic Diseases
Acute Diseases:
Broken Bone
Asthma Attack
Tonsillitis
Chickenpox
Chronic Diseases:
Diabetes
Osteoporosis
Heart Disease
Arthritis
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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.
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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.
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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
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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.
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Communicable and Non-Communicable Diseases Examples
Communicable Diseases:
Measles
HIV
Strep Throat
Salmonella
Non-Communicable Diseases:
Cancer
Diabetes
Congestive Heart Failure
Alzheimer's Disease
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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.
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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
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Methods of Disease Transmission
Direct Transmission:
Disease is passed directly from one infected person or animal to another.
Indirect Transmission:
Disease is transmitted without direct contact.
Vector Transmission:
Requires another organism to transfer disease.
Person-to-Person:
Occurs through touch or exchange of body fluids.
Droplet:
Spread by coughing or sneezing, causing infectious droplets to land nearby.
Fecal-Oral:
Transmitted via microscopic fecal matter reaching the mouth.
Airborne:
Spread through the air from an infected individual’s respiratory actions.
Fomites:
Inanimate objects can transmit disease, such as contaminated surfaces or water fountains.
Insect Bite:
Common method is through vectors like mosquitoes.
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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.
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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.
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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.
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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.
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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.
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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.
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Symptoms of Lyme Disease
Lyme disease progresses through three stages, each characterized by specific symptoms, which can evolve without treatment:
Early Localized Stage: Symptoms may include skin rash, headaches, flu-like symptoms, fatigue, and swollen lymph nodes.
Disseminated Stage: Symptoms can include multiple rashes, heart palpitations, severe joint pain, memory issues, and neurological symptoms.
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.
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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.
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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.
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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.
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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.
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Reminders
Homework: HW #2 posted and due on 9/22.
Reading Check: RC #4 due on 9/17.