IVP 2,001 Pathogenesis - Key Concepts (Last-Minute Review)

AVBS 2,001: Introductory Veterinary Pathogenesis (IVP) at Sydney Uni; focus on wildlife health, pathology, and disease ecology.
Instructor: Damien Higgins; interests in environment-health interactions, wildlife disease, and koalas.
Emphasis on how environmental changes, pathogens, and wildlife ecology shape disease risk and health outcomes.

Veterinary and animal science careers span disease management, policy, biosecurity, public health, diagnostics, vaccine/therapeutic development, and lab animal work.
Animal health training provides transferable skills for human health and comparative medicine; differences and similarities across species are important.
Emerging diseases are more likely with global changes; host, pathogen, and environment interactions drive emergence.
Technology advances (diagnostics, AI) will transform the field; require critical appraisal and rigorous validation of AI outputs.
Fundamental knowledge and critical thinking are essential to adapt to new tools and contexts.

Disease arises from a complex interaction among the host, the pathogen, and the environment (the HPE triad).
Disease is a disturbance of the structure or function of the host's tissues.
Clinical disease shows observable signs; subclinical disease is present without visible signs.
Pathogen (etiological/agent of disease) may not always cause disease; outcome depends on host, pathogen attributes, and environment.
Infectious agents are living organisms (bacteria, viruses, parasites); contagious means transmissible between hosts; infectious does not always imply contagious.
Other agents of disease include toxins, deficiencies, genetic defects, physical agents, etc. Dose matters for toxicity/deficiency effects.
Exposure → colonisation → infection can lead to disease depending on host-pathogen-environment interactions.

Pathogenesis: development of disease (trigger, mechanism, outcome).
Pathology: study of disease; structural and functional manifestations.
Pathophysiology: physiology of disease (biochemical/physiological processes).
Epidemiology: study of disease dynamics in populations.
Disease states framework: infection, colonisation, subclinical, clinical, recovery, latency (diagnostic tests vary by state).
Five main pathological processes were historically described; this course emphasizes four core host responses with immunology linked to inflammation, and notes tissue deposits/pigments as niche processes.
All mechanisms are host responses to an agent of disease; these responses can be beneficial or damaging depending on context.

$4$ main processes:
- 1) cell injury (direct injury, hypoxia, toxins, etc.)
- 2) inflammation and repair (including immunology as its functional basis)
- 3) circulatory disturbances (vascular issues, edema, congestion, hemorrhage)
- 4) disorders of growth (neoplasia, atrophy, dysplasia)
These processes interact with each other and with tissue microenvironments.
The environment (systemic and local) shapes the host's response and the pathogen's behavior.

Disease is studied at multiple levels: cellular, tissue, organ, individual, herd/population, and global/environmental context.
Cellular ecosystem within tissues includes host cells, resident and invading microbes, immune components, and nutrient/oxygen availability.
Tissue-level changes reflect underlying cellular/pathway events and determine clinical/subclinical outcomes.
System-wide factors (weather, socioeconomics, politics) influence disease dynamics at the herd/global level.

For each pathological process, identify:
- Trigger: what starts the process
- Mechanism: the cellular/molecular events driving it
- Outcome: the tissue/physiological changes seen clinically or histologically
Build your understanding from structure to details: frame first, then mediators and molecules.

Key disease states to recognize: infection, colonisation, subclinical disease, clinical disease, recovery, latency.
Diagnostic approaches span multiple disciplines:
- Parasitology, microbiology, histopathology, molecular methods
Understand strengths, weaknesses, and appropriate use of each test for different disease states.

Foundational knowledge assumed: structure, morphology, metabolism of bacteria, viruses, fungi.
Basic histological structure and function of cells and tissues (blood vessels, skin, liver, lung, kidneys, intestine, immune system).
Early emphasis on histology and integrating anatomy with disease; engage with histology prep and practicals early.

Build a learning structure: frame (trigger, mechanism, outcome) before details.
Explore Canvas site for unit info, schedule, and modules; lectures moved online (asynchronous) with face-to-face practicals and tutorials (~ $2$ hours weekly).
Attendance via QR codes; check Canvas for attendance requirements.
Expect to complete preparatory quizzes before interactive sessions; come prepared to participate.
Use the discussion board for questions after consulting Canvas content first.

First face-to-face exercise is in week $2$ ; lectures/quizzes for week $2$ posted before then.
Weekly modules organize content by topic; content, quizzes, and assessments are on Canvas.
Schedule and assessments are documented in the unit information and end-of-study outline.