Immune System Malfunction and Infection

Three Main Ways the Immune System May Malfunction

1. Hypersensitivity

   • Exaggerated or inappropriate immune response to an antigen/allergen.
   • Causes inflammation or destruction of healthy body tissue.

2. Autoimmune Reaction

   • Normal defenses recognize self cells as non-self.
   • Causes: Genetic, hormonal, or environmental factors.

3. Immunodeficiency

   • Absent or depressed immune response.
   • Causes: Infection, medications, genetic disorders.
   • Increases risk for infections.

Chain and Stages of Infection

Chain of Infection

• Causative Agent: Bacteria, virus, or toxin.
• Reservoir: Human body or soil.
• Portal of Exit: Respiratory tract, blood, etc.
• Mode of Transmission: Droplets, contact, airborne.
• Portal of Entry: Susceptible host.

Stages of Infection

1. Incubation Period

   • Pathogen enters and multiplies.
   • No symptoms.

2. Prodromal Stage

   • Pathogen multiplies.
   • Onset of general symptoms (malaise, fever).

3. Illness Stage

   • Onset of specific symptoms (e.g., respiratory symptoms).

4. Convalescence Phase

   • Symptoms subside and disappear.
   • Gradual recovery.

Risk Factors for Infection

• Compromised immunity.
• Chronic or acute disease (e.g., diabetes).
• Poor hygiene and sanitation.
• Crowded living environments (e.g., dormitories).
• IV drug use and unprotected sex.
• Impaired skin integrity.

Differences in Infection Symptoms

Systemic Infection Symptoms

• Fever, malaise, chills, fatigue.
• Tachypnea, tachycardia.

Local Infection Symptoms

• Edema, pain, erythema (redness).
• Decreased function, warmth in affected area.

Prioritization in Clinical Settings

• Prioritize patients with systemic infection symptoms over those with local infection symptoms.

Upcoming Topics

• Diagnostic tests related to the immune system.
• Detection of infection and inflammation.

Note: Stay tuned for more information on diagnostic tests in the next session.