4 Disease origins, infections and transmission Flashcards
(22 cards)
What causes a disease to be ‘emerging’?
🌍 ↗ Human behaviour, demographics
🌱 Environmental change
💊 Antimicrobial resistance
Why might a disease seem new?
🔬 Previously unculturable orgs (e.g. H. pylori)
🦠 New zoonotic spillover
How do commensal microbes support health?
🧬 Homeostasis, immune dev., pathogen protection
Normally X inflammatory if barriers intact
When can normal flora cause disease?
💊 Antibiotics → imbalance
🧍♀️ Immunocompromised → opportunistic infection
Where is normal flora found?
🧍♀️ Non-sterile sites → skin, mucosa, bowel, rectum, vagina
What are miasma theory + spontaneous generation?
🌫 Miasma = disease from “bad air”
✨ Spont. generation = life from non-living matter
How did Pasteur disprove spontaneous generation?
🧪 Swan-neck flask: sealed = sterile; exposed = cloudy
Who first saw microbes?
🔬 Van Leeuwenhoek (1664) → “wee animalcules”
What infection control advances followed germ theory?
🧼 Holmes (1843) → puerperal fever
🧼 Semmelweiss (1847) → handwashing
🏥 Nightingale (1850s) → hygiene reform
What was the first major vaccine?
🐄 Cowpox → Smallpox vaccine (18thC, England)
How did John Snow contribute to epidemiology?
🚰 1854 cholera → traced to contaminated water pump
What is a pathogen?
🦠 Microbe that causes disease + tissue damage (pathology)
What is an infection?
📌 Persistence/multiplication of pathogen in/on host
How do microorganisms spread between hosts?
📈 Changing human behaviour, population movement (implied)
🦟 Vectors (e.g. arthropods)
💧 Environment (e.g. water)
How do pathogens spread within the host?
↘ Via blood, lymph, tissue invasion (not explicit but implied)
What is the global burden of infectious disease?
📉 Major YLD cause
#10 in Aus
LICs = communicable dom. (e.g. malaria)
HICs = NCDs (e.g. cancer)
What factors increase infectious disease burden in LICs?
🍽 Malnutrition
🚱 Poor sanitation
🏥 Inadequate healthcare
🌎 Concentrated in Global South
How do microorganisms cause disease (general principles)?
🧫 Entry → adherence → multiplication → evasion → tissue damage
How do viruses cause disease (example)?
🧬 Use host machinery → kill/injure cells
e.g. Hepatitis viruses = unrelated viruses → liver inflammation
How do bacteria cause disease (example)?
⚠️ Direct damage via toxins, enzymes
🧬 Indirect damage via immune response
e.g. Streptococcus → tissue inflammation
What are the anatomical barriers that protect against infection?
Skin and mucous membranes.
How do skin and mucous membranes contribute to defense?
Skin is an excellent barrier (only breached by cuts); mucous membranes are more vulnerable but protected by mucus and antimicrobials.
