Whats a vector?
organism that transmits a disease causing pathogen
Whats an infectious disease?
• Caused by an organism (pathogen) in a host i.e. virus or bacteria
• If host successfully controls pathogen, disease does not occur
• Can be caused by microscopic and macroscopic organisms
• Can be transferred from one organism to another
Direct: pass directly from person to person
Via Vector: passed on through intermediary e.g. anopheles mosquito (malaria)
Whats an non-infectious disease?
• Not caused by an organism
Example of infectious disease.
colds, influenza, chicken pox, herpes and measles
Examples of non infectious disease.
• Genetic diseases e.g. Down syndrome & haemophilia
• Lifestyle/Environment diseases
e.g. Cardiovascular disease, lung cancer & skin cancer
Why should we practice cleanliness of water, food and hygiene?
- Intake of food and water = easy way for micro-organisms to enter our bodies
- Minimising number of micro-organisms in food & water = reduces risk of infection
- Good personal hygiene = ensures body openings are clean prevent micro-organisms entering
- In sterile conditions = no microbes present
Practices of cleanliness that assist in control of disease?
• Prevent contamination of food and water through:
Proper sanitation
Proper food handling
Personal hygiene
Water treatment processes
• Prevent decomposition and spoilage of foods
• Prevent transmission of disease and infection
Use disinfectants, sterilisation and antiseptics
Minimise contact with food & water
Avoid crowded conditions, poor sanitation and untreated sewage ALL increase spread of disease
Define pathogen?
any organism that produces a disease
Describe what a pathogen is
• Parasite/organism living in another organism – can cause disease
• Two types:
1. Micro-organisms
2. Macro-parasites [endoparasites (in body) & ectoparasites (outside body)]
Conditions - to be a disease-causing pathogen, it must….
• Have enough virulence (number of particular pathogen to cause disease)
Virulence needed only small amount
• Enter through certain part of host or survive without being destroyed by natural acidity and mucus
• Escape from one host to another and SURVIVE
Identify data sources, plan and choose equipment or resources to perform a first-hand investigation to identify microbes in food or water
List the equipment used here in microbiology.
• Agar plates: petri dishes filled with a sterile, jelly-like substance extracted from seaweed (AGAR)
• Different types of agar are used for different purposes
• Techniques:
Selective media: allows certain organisms to grow while inhibiting others
Differential media: for differentiating closely related organisms
Enriched media: supplemented with highly nutritious materials such as blood & serum, to make it grow bigger
• Need to sterilize area to prevent contamination from other micro-organisms
Identify data sources, plan and choose equipment or resources to perform a first-hand investigation to identify microbes in food or water: name the aim
To culture microbes growing in probiotic yoghurt, and to identify them
Identify the method to this aim ‘To culture microbes growing in probiotic yoghurt, and to identify them ‘
Method:
- Collect a tub of probiotic yoghurt
- Sterilise an inoculating loop with a blue-flame Bunsen burner and use it to collect samples of the yoghurt and spread over the agar
- Place the lid on the plate, then label and seal. DO NOT REOPEN THE PLATE
- Incubate (temperature depends on what you’re growing)
- Observe growth of colonies.
a. Shiny smooth colonies - Bacteria
b. Furry colonies - Fungi - Disposal = Autoclaving (steam sterilisation)
Name a conclusion to “Aim: To culture microbes growing in probiotic yoghurt, and to identify them”
• Shiny smooth colonies = Bacteria
Furry growth of mycelium = Fungi
Name the six stages of water treatment.
- Coagulation
- Flocculation
- Sedimentation
- Filtration
- Disinfection
- Source control
Describe the step in water treatment ‘Coagulation’
- Removal of particles from drinking water through insertion of a coagulant (usually ferric or aluminum salts)
- Salts dissolve into water to form positive ions which attract negatively charged particles
Describe the step in water treatment ‘Flocculation’
- Floc removed by filtration or settling processes
* Floc examples include: alum & iron compounds
Describe the step in water treatment ‘Sedimentation’
• Particles settle to bottom of dam/catchment
Describe the step in water treatment ‘Filtration’
- Removal of very small particles such as viruses and protozoans
- Filters can be made of sand, gravel of charcoal
Describe the step in water treatment ‘Disinfecton’
- Chlorination, chloramination and ozonation
* Fluoride added to prevent tooth decay
Describe the step in water treatment ‘Source Control’
- Protection from primary infection
- Proper fencing
- Adequate distance from farms where fertilizers and pesticides are used
- Distance from sewage systems
How does Coagulation help reduce risk of pathogens?
Removal of suspended particles that attract and hold bacteria and viruses
Removes about 99% of bacteria and viruses
How does Flocculation help reduce risk of pathogens?
Prevention of disease from pathogens
How does Filtration help reduce risk of pathogens?
Removal of suspended particles that attract and hold viruses and protozoans
Removes about 99% of viruses and protozoans
