Infectious Diseases and Pathogens 1

Introduction to Infectious Diseases

  • Overview of the topic of infectious diseases as a significant health concern.

Emphysema and COPD

  • Key Characteristics of Emphysema:

    • Characterized by alveolar destruction.

    • Different from bronchiolar issues, emphasizing the loss of surface area for gas exchange, leading to difficulty in breathing.

    • Lungs do not recoil effectively due to the damage, making expiration harder.

  • Muscle Involvement in Breathing:

    • Internal intercostals are the muscles involved in exhalation during emphysema.

  • Obstructive Lung Disease:

    • Identified as a condition where breathing patterns change.

    • Comparison to breathing through a straw:

    • Inability to fully exhale leads to overinflation of lungs.

    • Total lung capacity (TLC) and residual volume (RV) are altered due to air trapping.

  • Lung Volumes:

    • Tidal volume remains the same but is less efficient due to the condition.

  • Restricted Lung Diseases:

    • Lung volume curves appear compressed, indicating difficulties in lung expansion.

  • Alveolar Ventilation Efficiency:

    • Optimal alveolar ventilation is achieved with deep breaths and higher respiratory rates.

    • Shallow breaths lead to waste through dead space, reducing effective ventilation.

  • Complications of COPD:

    • Right Ventricular Heart Failure:

    • Caused by pulmonary hypertension resulting from low oxygen perfusion throughout the lungs leading to pulmonary vasoconstriction.

    • Right heart works harder to pump blood through narrowed pulmonary arteries, resulting in heart failure.

Epidemiology of Infectious Diseases

  • Common Causes of Infectious Disease Mortality:

    • Flu and pneumonia ranked lower than cancer and heart disease in overall mortality but are significant killers, particularly of older populations.

    • Age-related mortality trends:

    • Increased likelihood of dying from cancer or heart disease with aging.

    • Infectious diseases significantly affect the elderly, although younger populations face risks from accidents.

  • Impact of COVID-19:

    • COVID-19 became a leading cause of death during the pandemic.

    • Increased mortality from other conditions like heart disease and cancer due to patients delaying treatments during the pandemic.

Pathogens

  • Definition:

    • Pathogens are disease-causing agents, known colloquially as germs or infectious agents.

    • Derived from Greek pertaining to suffering and passion, indicative of illness.

  • Transmission and Infection Classes:

    • Pathogens can be bacteria, viruses, fungi, parasites, or prions.

    • Each type of pathogen has distinct transmission methods and symptom profiles.

Bacteria vs. Viruses

  • Bacteria:

    • Single-celled organisms that can reproduce independently.

    • Examples include E. Coli, which is commonly found in undercooked or contaminated foods, causing gastrointestinal distress such as nausea and diarrhea.

    • Antibiotics are effective on bacteria but not on viruses.

  • Viruses:

    • Comprise genetic material surrounded by a protective coat and require host cells for replication.

    • Antibiotics have no effect; antiviral drugs are necessary for treatment.

  • Importance of Proper Antibiotic Use:

    • Misuse can result in antibiotic resistance. Patients must complete prescribed courses to prevent resistant strains from developing.

Fungal Infections

  • Common types of fungi include black mold, athlete's foot, and Candida auris.

  • Mold exposure can lead to respiratory issues, emphasizing the importance of cleaning and wearing masks in affected areas.

Parasites

  • Types of Parasites:

    • Protozoa (e.g., Giardia), larger worms (e.g., roundworms, flatworms).

    • Transmission via contaminated water or food, emphasizing proper hygiene.

  • Vectors:

    • Ticks and fleas can carry bacteria (e.g., Lyme disease) without causing disease themselves but act as vectors for infections.

Prions

  • Definition and Examples:

    • Prions are misfolded proteins that cause neurodegenerative diseases (e.g., mad cow disease).

  • Fatal with no known cure, leading to severe health complications.

Entry Modes of Pathogens

  • Pathogens can enter via several orifices, including the eyes, nose, mouth, and through cuts.

  • Specific entry methods based on the pathogen type:

    • Respiratory paths for respiratory illnesses, ingestion for GI tract pathogens, etc.

Breaking the Chain of Infection

  • Chain of Infection Steps:

    • Pathogen -> reservoir -> portal of exit -> mode of transmission -> portal of entry -> susceptible host.

  • Strategies to break the infection chain include:

    • Isolation of affected individuals.

    • Use of masks to contain pathogens.

    • Hygiene and sanitation practices to minimize transmission.

Immune Response

  • Innate vs. Adaptive Immunity:

    • Innate Immunity: Immediate, nonspecific response to pathogens with histamine release causing inflammation.

    • Adaptive Immunity: Slower, highly specific response, learning from previous encounters to improve defense.

  • Phagocytosis as a defense mechanism, where white blood cells engulf and destroy pathogens.

Conclusion

  • The lecture will continue to cover adaptive immunity, further exploring the body’s response mechanisms to infectious diseases.