Transmission Of Disease Flashcards
What must pathogens be able to do to persist and live on?
- Leave infected host.
- Survive transmission in environment.
- Enter susceptible persona or animal.
- Develop/multiply in newly infected host.
What does the spread of infection require?
- Agent (pathogen)
- Reservoir (human, animal, food)
- Exit (coughing, vomit, breaks in skin)
- Mode of transmission (contact, droplets)
- Portal of entry (cuts, mouth, nose)
- Susceptible host (weakened immune system, babies, elderly).
What type of disease transmission is from mother to child?
Vertical
What type of disease transmission is from person to person?
Horizontal
Examples of direct transmission?
Touching
Kissing
Oral secretion
Body lesions
Intercourse
Examples of indirect transmission?
Vehicles; Air/droplets, Water, Soil, Food, Blood, Saliva.
Vectors; living organisms such as insects, fleas, flies.
What are fomites?
Objects or material which are likely to carry infection (bed, computer keyboard, phone)
How is infection spread to blood and bodily fluids?
Blood or fluid from infected person come into contact with mucous membrane or bloodstream of uninfected individual.
How is diseased transmitted through air/droplets?
- Droplets from respiratory system of infected person (sneezing, coughing, talking), enter upper and lower respiratory tract of a host.
What must organisms be capable of if transmitted through air and droplets?
Capable of surviving outside of body and resistant to drying out.
What is meant by preventing ingress?
What defences do we have as humans to prevent microbes from entering system.
What is meant by dealing with ingress?
Defence mechanisms which deal with microorganisms once they have gained ingress.
Examples of preventing ingress
- Mucocillary escalator
- Skin
- Fatty acids and salts
- Saliva
- Gingival crevicular fluid
- Blood
- Blood brain barrier
What is the mucocillary escalator?
Mucous and cilla lining the respiratory tract. The mucous traps the microbes and the cilla beats to remove mucous from lungs.
Continual processes that trap and sweep away particles up the epiglottis to be swallowed.
What do the glands in the skin secrete to prevent ingress?
Fatty acids and lysozyme (kill bacteria)
Which layer of skin serves as the mechanical barrier?
Keratinised layer, constantly renewed.
How does saliva prevent ingress?
Contains many antibacterial agents and has lavage/cleansing effect
How does gingival crevicular fluid prevent ingress?
Inflammatory exudate/fluid that’s collected at gingival margin. Contains immunological defence mechanisms.
How can blood prevent ingress?
Entry of infection through wounds is a major source.
However the blood is flushed through and clots forming a scab for another barrier.
What is the blood brain barrier and how does it prevent ingress?
Specialised filter surrounding the brain and spinal cord. Acts as a physical barrier to prevent toxins and some microorganisms from entering but allowing glucose
What are the ways to deal with ingress?
Immune response
Variable response
How does the host response deal with ingress?
- Recognises and destroys foreign organisms and substances that enter body.
- Distinguishes from body’s own tissue and antigens.
- Immune systems remembers prior antigen encounters, this aids for faster and better response next time.
What are lymphocytes?
White blood cells that develop in bone marrow and circulate throughout lymphatic system.
What are B Lymphocytes?
Attacks outside of cells.
