Disease Transmission in Detail

Part of Pathogens and Disease Transmission · Section 5 of 19

Deep DiveUnit: Infection & ResponseGCSE

This deep dive covers Disease Transmission in Detail within Pathogens and Disease Transmission for GCSE Biology. Types of pathogens, how diseases spread, transmission methods, and prevention strategies It is section 5 of 19 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

Disease Transmission in Detail

1. Direct Contact Transmission

  • Mechanism: Pathogens pass directly from infected to healthy person through physical contact
  • Examples: Skin infections, sexually transmitted diseases (STDs), some viral infections
  • Prevention: Avoid contact with infected individuals, use protective barriers

2. Airborne Transmission

  • Mechanism: Pathogens travel in droplets through the air when infected people cough, sneeze, or talk
  • Range: Droplets can travel 1-2 meters and remain airborne briefly
  • Examples: Tuberculosis, influenza, measles, COVID-19
  • Prevention: Masks, good ventilation, isolation, covering coughs

3. Vector Transmission

  • Mechanism: Animals (vectors) carry pathogens from infected to healthy hosts
  • Vector examples: Mosquitoes (malaria), ticks (Lyme disease), rats (plague)
  • Malaria cycle:
    1. Mosquito bites infected person, takes up Plasmodium protists in blood
    2. Protists reproduce and develop inside mosquito
    3. Mosquito bites healthy person
    4. Protists are injected into new host's bloodstream
  • Prevention: Control vector populations, protective clothing, mosquito nets
Painted 4-stage Plasmodium malaria cycle: (1) infected Anopheles mosquito bites a person, injecting Plasmodium protists into the bloodstream; (2) protists multiply inside red blood cells, causing fever and chills as cells burst; (3) a healthy mosquito bites the infected person and takes up protists in the blood; (4) protists multiply inside the mosquito, ready to infect the next person. Centre shows a close-up of a single Plasmodium protist. Parchment notes Plasmodium is a single-celled protist (not bacterium or virus), Anopheles mosquito is the vector, and prevention uses nets and insect repellent.

4. Water and Food Transmission

  • Mechanism: Pathogens contaminate water supplies or food
  • Examples: Cholera (water), Salmonella (food), E. coli (contaminated vegetables)
  • Prevention: Clean water supplies, proper food preparation and storage, good sanitation

Practice questions for Pathogens and Disease Transmission

What is a pathogen?

  • A. A microorganism that causes disease
  • B. A type of white blood cell
  • C. An antibody produced by the immune system
  • D. A nutrient required for growth
1 markfoundation

Explain why viruses need to infect host cells in order to reproduce.

3 marksstandard

Quick recall flashcards

What is a pathogen?
A microorganism that causes disease in living organisms
What is direct transmission?
When pathogens are passed directly from one person to another through physical contact

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Specific Disease Examples

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