Transmission of Pathogens Flashcards
What are the 4 mechanisms of transmission?
1) Direct/indirect contact
2) Transfer of body fluids
3) Disease-specific vectors
4) Contaminated food and water
What is the mechanism of direct/indirect contact?
Pathogen is spread by physical contact with an infected person
Pathogen is spread by contact with an object that an infected person has contaminated.
What is the mechanism of transfer of body fluids?
Blood/other body fluids of an infected person come into contact with mucous membranes/bloodstream of an uninfected person. May also occur via inhalation of droplets.
What is the mechanism of disease-specific vectors?
When other animals (e.g. ticks, insects, mites) transfer the pathogen. Some non-specific vectors transfer the pathogen to water which is then consumed.
What is the mechanism of contamination of food or water?
Food or water containing pathogens is ingested, where it can cause disease.
Define a pathogen.
A foreign organism which can cause disease
What are the 2 most common pathogens?
Bacteria and viruses.
Explain bacteria structure
- single cell
- cell wall
- no membane-bound organelles
- no nucleus - DNA is tangled
How do bacteria reproduce?
Via binary fission - asexual reproduction
What are four classifications of bacteria?
Cocci - spherical (single, pairs, clumped)
Bacilli - rod, often has flagella
Spirilla - spiral/twisted
Vibrio - comma shaped
Explain virus structure.
- protein wall
- no cell wall
- DNA/RNA plasmids
- smaller than bacteria
(e.g. HIV, bacteriophage, adenovirus)
Contrast disease-specific and non-disease-specific vectors with examples.
Disease specific vectors carry one or two pathogens. e.g. mosquitos and malaria.
Non-specific vectors can carry multiple pathogens. e.g. flies transfer pathogens to water
Contrast disease-specific and non-disease-specific vectors with examples.
Disease specific vectors carry one or two pathogens. e.g. mosquitos and malaria.
Non-specific vectors can carry multiple pathogens. e.g. flies transfer pathogens to water
What are the two methods that bacteria are classified by?
Morphology and gram stains
A bacteria with a negative gram stain has…
All 3 layers, and is more dangerous.
Light colour.
