U4 AOS 1 Flashcards
Pathogen
An agent that causes disease.
Cellular Pathogen
Have a cellular structure and are living organisms
Cellular Pathogen - Bacteria
Unicellular Pathogen that can cause disease through toxin and enzyme production to alter cell functioning.
Non Cellular Pathogens
Do not have a cellular structure and are non-living.
Non Cellular Viruses
An infectious agent composed of genetic material inside a protein that can not independently reproduce.
Disease Control Methods
Prevention:practising personal hygiene, drinking clean water, using condoms and bug spray
Vaccination: to provide long-term protection against infectious diseases
Medication: to manage infectious diseases, e.g, antibiotics for a bacterial infection
Surveillance: Monitor disease to prevent outbreaks
Modification: make environment less suitable for microbe growth
Infection Control: prevent spread. Sterilisation,isolation, and hygiene.
Disease
A condition that impairs the normal functioning of an organ,structure, or system
Infectious disease
Can be transmitted from one person to another
Eg. Cholera
Caused by pathogenic agents.
Non- Infectious disease
Can not be spread from affected person via the environment
Eg. Cancer
Emerging Disease
Disease caused by an unknown agent that has spread to humans from another species
Re-Emerging disease
Reappears after a decline in incidence
Endemic Disease
Constantly in low levels in the population
Outbreak
Sudden disease increase locally
Epidemic
Infectious disease spreads across nation
Pandemic
Disease spreads across the world in 3 countries in 2 regions
Triad model of infection
Pathogen; the disease causing organism
Host; target of the disease
Environment; conditions that allow transmission.
Physical method to identify virus
Identify vurus based on size and shape.
X-ray crystallography; determines structure
Electron microscopy; determines image to identify.
Immunological Methods
Detects Antigens or antibodies
(ELISA) enzyme-linked immosorbent aasay.
A. Direct Elisa.
B. Indirect Elisa.
C. Sandwich Elisa.
Direct Elisa
- a viral antigen is ppaces on a surface.
- Matching primary antibodies bind to this antigen.
- The primary antigens have an enzyme indicator.
Steps
1. Coat plate with antigen
2. Antibody specific to antigen is added to wells
3. During incubation, antibodies bind to antigen
4. Wells washed to remove unbinded antibodies
5. Enzyme substrate added to test positive
Indirect Elisa
Primary antibodies do not have an enzyme indicator
Instead: The enzyme indicator is attached to a secondary antibody… This helps to amplify signal.
Sandwich ELIZA
Antibodies bind to the surface
Phenotypic Methods
Techniques that involve identifying traits or features
Genotypic + Molecular methods
Examines genetic material to identify
Patient Zero
The 1st person to contract disease.
Important as; helps to identify how a pathogen can be spread and what organisms can spread
Reserviours and Hosts
Transmission occurs when a pathogen leaves hosts and is transmitted to another.
Reservoir: the habits in which a pathogen lives,grows, and multiplies
Host: infected person
Direct Transmission
Person to person contact
Indirect Transmission
Airborne or contaminated objects
Vectors
Carry pathogenetic agents and spread them.
Ticks, fleas, etc.
Incubation Period
The interval between exposure and onset.
During this: the disease- causing agent multiplies to make symptoms.
Asymptomatic Carriers
Infected but does not show sign or symptoms
Subunit Vaccine
Contains part of a micro-organism to produce an immune response
Whole-Agent
Contains whole non-virulent micro-organism
Live Attenutated Vaccines
Weakened live microbe created in a lab, using repeated culturing
Advantages
- single dose has long lasting effects
Disadvantages
- can harm foetuses
- can cause disease in a weak immune system
Inactivated Vaccines
Contains microbes that have been inactivated by heat or radiation
Advantage; can be used in people with weak immune systems
Disadvantage
- stimulates a weak immune system
- requires boosters to maintain
Sub-Unit Vaccine
Labgrown pathogen with chemically extracted antigens
Advantages; safe, stable, easy to store
Disadvantages; requires multiple doses
Toxoid Vaccines
A type of recombinant subunit vaccine that uses toxins inactivated by formalin to stimulate adaptive immunity
Why are Vaccines given:
To reduce spread and build immunity
Graph.
Monoclonal Antibodies
Artificially produced antibodies that bind to one type of antigen
STEPS:
1) Injects mouse with antigen X to make B cells and antibodies
2) repeat injections to increase concentration
3) Remove spleen + culture to separate cells
4) b cells form + fuse with tumor cells = hybridomas
5) unfused cells die leaving only hybridomas
6) hybridomas are cultured in a medium to divide repeatedly
7) cells are checked for antibody presence
8) antigen x harvested
9) injected into subject
Natural Immunity
Occurs through contact with a disease causing agent
Artificial immunity
Occurs due to intentional exposure and intervention
Ways to control pathogen spread
Sterilisation and chemical agents such as antiseptic and disinfectant
Inflamation
2nd line of defence
Steps
Initiation: bacteria breeches 1st line of defence (intact skin)
Migration:
- cytokines are released and attract neutrophils
- Fluid with peptides and proteins enters tissue
Resolution:
- platelets with clotting factors are released
- neutrophils kill invading antigen.
