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Causes of Disease

Causes of Disease. 4-H Veterinary Science Extension Veterinary Medicine  Texas AgriLife Extension Service College of Veterinary Medicine and Biomedical Science Texas A&M System http://aevm.tamu.edu. Objectives . Distinguish between infectious and non-infectious causes of disease

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Causes of Disease

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  1. Causes of Disease 4-H Veterinary Science Extension Veterinary Medicine  Texas AgriLife Extension Service College of Veterinary Medicine and Biomedical Science Texas A&M System http://aevm.tamu.edu

  2. Objectives • Distinguish between infectious and non-infectious causes of disease • Discuss risk factors • Discuss primary cause factors • Discuss secondary cause factors

  3. Infectious Diseases • Infectious disease • An illness due to a specific infectious agent or its toxic products that arises through transmission of that agent or its products from an infected person, animal or reservoir to a susceptible host, either directly or indirectly

  4. Agents involved • Germs • Bacteria • Viruses • Fungi • Rickettsiae • Helminths • Protozoa • Arthropods

  5. Damage caused • Feed off of body tissue • Reproduce in tissue • Release toxins • Pressure

  6. Reproduction • Lag phase • Usually incubation period where organism is settling in to new surrounding • Growth phase • Exponential growth is rapid • Plateau phase • Growth = Death Plateau Phase Number of Organisms Growth Phase Lag Phase Time

  7. Lag phase maybe long • Non-disease dormancy or latency • multiple when conditions are optimal or when organism is ready • May break if bacteria is in stressful environment • Bacteria and virus are precipitated by stress • Ex. Anthrax go into dormancy (spore form) when exposed to oxygen, once in anaerobic environment, bacteria multiply and cause fatal disease • Causes disease

  8. Non-Infectious Disease • Disease cause • Dysfunction or disorder of reproductive disease • Example - hypo/hyper-thyroidism • Nutritional deficiencies or imbalances • Example - copper toxicity - damage liver • Chemical and plant poisoning • Example - acorns and green tomatoes • Physical injuries and stress

  9. Causal pathway • Variables present B C C B D A A D H E E G F F Diseased Non-Diseased

  10. Primary Cause • ALWAYS present when occurs and • Risk factors increase or decrease probability of disease in individual • Disease • Example - not washing hands after using restroom • Dysfunction • Example - cryptorchidism • Disorder • Example - type 1 diabetes - body does not produce enough insulin

  11. Secondary Causes • Primary cause not as evident • Secondary is noticeable when individual is sick • Need tissue damage from primary cause • Invade and multiply Dividing Bacteria Video

  12. Risk Factors • Causative factors • Increase chances of getting sick • Examples • Overcrowding • Pollution • Weather • Inbreeding

  13. Protective factors • Decrease chances of getting sick • Examples • Vaccination • Husbandry • Crossbreeding • Good management practices

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