investigate modes of transmission + Adaptations of different pathogens

Question 1

Direct contact

Answer 1

Transfer of the pathogen via exposure to infected skin or body secretions (Human-to-human contact).
→ Skin touching, kissing, paternal care

Question 2

Indirect contact

Answer 2

Transfer of the pathogen to a new host via a non-living object (Not human-to-human contact).
→ Cough, sneeze, touching surface

Question 3

Vector transmission

Answer 3

Transfer of the pathogen via another organism, such as an arthropod.
-Mosquito

Question 4

Prions

Answer 4

→ ‘Piggyback’ other proteins to facilitate movement through the gut.
→ Secrete substances that allow invasion of lymphoid (Lymphatic system - removes fluids that leak from blood vessels) tissues.
→ Prions then invade nervous tissues and travel to the brain.

Transmission route
→ Mainly unknow
→ Verticle (Mother to child) - Can transmit across
→ Indirectly through infected meat

Question 5

Viruses (Must have a good understanding)

Answer 5

Adhesion
→ Viral surface proteins adhere to the surface of the host cell.
Invasion
→ Viruses enter cells through endocytosis (Viruses are enveloped and enclosed in a membrane) or by delivering viral genome (Genetic material inside that virus) through pores in the membrane.

Transmission
→ Direct contact (Can be blood-borne - use RBCs to facilitate growth
-Indirect contact with fomites
→ Airborne transmission - can stipulate sneezing/coughing,and remain suspended in the air.

Question 6

Bacteria (Must have a good understanding)

Answer 6

Adhesions
→ Use pili and fimbria (Hair like structure on the surface)
→ Adhesins on the surface resist the washing action of secretions (Urine, mucus)
→ form a biofilm (Community of bacteria attached to a host surface).
Invasion
→ Enzymes break down cell
→ Capsule of biofilm resist phagocytosis (Engulfment by WBCs)
→ CHemicals destroy immune defences
→ Toxins are secreted to damaged cells

Transmission
→ Direct contact
→ Indirect contact and infected substances/fomites
→ Airborne – stimulate sneezing/coughing, resist drying out in the air
→ Vector-borne transmission - produces proteins to attach to vectors; the vector is unaffected

Question 7

Protozoan

Answer 7

→ Microtubule penetrates host cell and facilitates entry, membrane is formed to protect from lysosomes

Transmission
→ Faeco-oral (E.g. infected food/ water) - induces diarrhoea and transmission
→ Direct contact

Question 8

Fungi

Answer 8

Adhesion
→ Assisted by cell wall/ capsule molecules
Invasion
→ Thermotolerance - heat shock proteins cope with body temperatures
→ Cell wall and capsules protect fungi from host attacks

Transmission
→ Direct contact
→ Airborne transmission
→ Soil-borne - form endospores to resist desiccation (drying), stable in a range of conditions

Question 9

Macroparasite

Answer 9

Hookworms
→ Secete proteins that reduce host cell responses
Ticks
→ Secrete molecules to prevent vasoconstriction, clotting or inflammatory response

Transmission
→ Direct contact