Zoonotic Diseases and Immune Response

Zoonotic Diseases

• Zoonotic diseases are diseases that can be transmitted between species.

Types of Diseases

• Bacterial: Tuberculosis
• Viral: Influenza
• Fungal: Athlete's foot
• Protozoan: Malaria
• Helminth: Schistosomiasis

HIV

• Genetic material: RNA
• Transmission: HIV transmission can potentially occur through casual contact or mosquito bites. (Note: There's a critical omission here about the actual modes of transmission)
• Target cells: Helper T cells
• Effect on the immune system: Decreases antibody production; affects lymphocyte counts

Immune System Components

• Antigens: Trigger immune responses; usually proteins or sugars.
• Plasma B cells: Produce antibodies.
• Helper T cells: Activate macrophages, B cells, and T killer cells. Crucial in the immune response—specifically HIV's target.
• Memory cells: "Remember" antigens for faster responses in future encounters; derived from B cells.
• Antibody production sequence: Antigen recognition → B & T lymphocyte activation → B lymphocyte division → Plasma cells produce antibodies
• Mast cells: Release histamine, triggering inflammation, allowing immune cells to reach infected areas.
• Phagocytes: Part of the innate immune system; engulf and digest pathogens through phagocytosis
• Lymphocytes: Produce antibodies in response to pathogens, providing specific immunity

Vaccines

• Types: Live attenuated, inactivated, subunit
• Mechanism: Vaccines stimulate memory cells, leading to faster, stronger immune responses during subsequent infections

Antibiotics

• Mechanism of action: Target bacterial processes (membrane, ribosomes, DNA replication), not viruses, making them ineffective against viruses.
• Resistance: Bacteria develop the ability to survive antibiotic treatment.
• Reducing resistance: Prescribing only for diagnosed bacterial infections helps.

First Line of Defence - Skin

• Mechanism: Acts as a physical barrier to pathogens.
• Wound healing: Blood clotting seals openings.

Immune Response to Bacteria

• Skin barrier: Provides a physical barrier; cuts lead to blood clot formation (scabs).
• Mucus and stomach acid: Mucus traps bacteria in the respiratory system. Stomach acid kills bacteria consumed by us.
• White blood cells: Identify, engulf, and destroy bacteria through phagocytosis.
• B and T cells: B cells produce bacteria-specific antibodies; T cells destroy infected cells.
• Memory cells: Some B and T cells become memory cells for long-term immunity.
• Antibodies: Bind to and help destroy pathogens.

Other Key Concepts

• Herd immunity: Reduces pathogen spread with a largely immune population.
• Blood clotting cascade: Released platelets → prothrombin to thrombin → fibrinogen to fibrin.
• Antibiotic effectiveness: Antibiotics block metabolic processes in prokaryotes.
• Pathogen elimination challenges: Antibiotic resistance and pathogen mutations make elimination difficult.
• Hand hygiene: Crucial for reducing antibiotic resistance.
• Vaccine response: Vaccines trigger activated B cells dividing into memory cells.