UNIT 4 - AOS 1 - CH6 Flashcards
Disease
“A condition in a living animal or plant that impairs the normal functioning of an organ, part structure or system”
Types of diseases
INFECTIOUS
“Communicate disease caused by pathogenic agents & transmitted from one individual to another”
= Cellular
= Non Cellular
EMERGING DISEASES: Caused by newly identified or unknown agent.
RE-EMERGING DISEASES: It appears after a significant decline in cases.
NON-INFECTIOUS DISEASES
“Disease that can spread from infected to healthy person via enviro”
= Genetic
= Nutritional
= Cancers
= Cardiovascular
Epidemic
- Uncontrolled spread of infectious disease
- Restricted geographical spread (localised) - Can become a pandemic
Pandemic
- Uncontrolled spread of infectious disease
- Wide global spread = at least 3 countries & 2 regions - Epidemic can become a pandemic
How do pandemics occur?
- Pathogen suddenly appears in geographical areas where human pop hasn’t had previous contact
- Illness occurs (usually first in animals) & becomes easily transmissible
- Uncontrolled spread of pathogen occurs worldwide.
Impact of European diseases on Aboriginal and TSI
Indigenous had no resistance to disease = major ^ in fatalities after first exposure
Effects the emergence of a disease can have
- large loss of life
- Long term health consequences
- Economy (cost to prevent spread, business closures, unemployment)
Vital that pathogens are identifies and controlled by understanding mode of transmission quickly
Identifying hosts
RESERVOIR
“The habitat in which a pathogen lives, grows and multiplies”
= humans, animals & enviro (do not experience disease)
SUSCEPTIBLE HOST
“An organism who can get the disease”
= Pathogen is transmitted from reservoir
= susceptibility depends on genetics, age, sex nutrition etc.
Epidemiological trial model
3 main components to help explain the main cause of disease emergence
- PATHOGEN (type of pathogen & disease-causing organism)
- HOST (target of the disease)
- ENVIRONMENT (Conditions allowing disease to be transmitted)
Modes of transmission
“How disease spreads from infected to healthy individuals”
DIRECT
= person-person contact (physical touch, kissing)
IN-DIRECT TRANSMISSION
= airborne (cough, sneeze)
= ingestion of contaminated food/water
= contact with contaminated objects
= vectors - organisms carrying disease (bite)
Difference between infection and disease
INFECTION:
“Pathogen enters body, overcoming defences & multiplying rapidly”
DISEASE:
“An infection that has developed into a disease as symptoms of disease are showing”
Incubation period
“The period after exposure, but before first symptoms of disease appear”
How to quantify the spread of a virus
= R0 values
They show the expected number of individuals that are infected by one individual.
R4 = one person can infect 4 people
Controlling the spread of disease aim & identify steps
To prevent spread and contain the disease
1. PREVENTION
2. VACCINATION
3. MEDICATION
4. MODIFICATION OF ENVIRO
5. INFECTION CONTROL STANDARDS
PREVENTION - in terms of controlling disease spread
- Improve hygiene
- Using insect repellent (can act as vector)
- Improved sanitisation
VACCINATION - in terms of controling disease spread
- Provides long-term immunity against infectious disease
- Help prevent spread & eradicate disease
MEDICATION - in terms of controlling disease spread
ANTIVIRALS
ANTIBIOTICS
Antivirals
“Type of medication used to treat viral infections”
- Virus is located within cells and undergoing replication
MODE OF ACTION:
- Prevent viral entry
- Prevent replication of viral genome
- Prevent synthesis of viral proteins
Antibiotics
“Type of medication used to treat bacterial infections”
- Kill microorganisms & inhibit growth
TYPES:
Narrow spectrum: act against limited variety of microorganisms
Broad spectrum: act against many diff microorganisms
Natural -> produced by other organisms
Semi-synthetic -> Produced partially by chemical synthesis
Synthetic -> produced by chemical synthesis
MODE OF ACTION:
- Inhibiting protein/enzyme synthesis
MODIFICATION OF ENVIRO - in terms of controlling disease spread
- Enviro made less suitable for pathogens to grow & be transmitted (e.g. vector control)
INFECTION CONTROL STANDARDS - in terms of controlling disease spread
- Sterilisation (kill microbes from surfaces using heat)
- Isolation (quarantine)
- Hygiene
- Antiseptics (inhibit pathogen growth on LIVING surfaces)
- Disinfectants (inhibit pathogen growth on NON-LIVING surfaces)
Sensitivity testing
Used for identifying the appropriate antibiotic that would be most effective to treat bacterial infection
STEPS:
1. Agar plate spread with bacteria
2. Small discs of diff antibiotics are added
3. Lack of growth around effective antibiotic
(Clean Zone = around effective antibiotics where it has killed bacteria)
Vaccination programs
“Mandated programs that set schedule vaccinations against specific diseases”
AIM:
- Reduce impact of vaccine-preventable infectious diseases
- Achieve ^ rates of immunity in community
NATIONAL VACCINATION PROGRAM:
- Outlines ages
- Been able to eliminate certain diseases from population due to mass vaccination
Overview of vaccine
- Developed vaccine is injected
- Immune system produces antibodies & memory cells against pathogen
- Boosters ^ antibody prod.
- Antibody is specific to treated pathogen = if contact with that pathogen occurs again immune system is ready.
Boosters
“Injection of vaccine given after longer interval between initial injection”
- Some vaccines are weaker & last for shorter period = need more than one
Herd immunity
“An indirect form of protection, as if the ^ proportion of population are vaccinated those without are protected”
- Only relates to contagious diseases
- Vulnerable people who can’t get vaccinated are protected (babies, elderly, cancer patients)
- Try to get pathogen of slowly disappear (pathogen can’t find hosts)
Immunotherapy
“Altering the immune response to fight diseases such as cancer & autoimmune disease”
STRATEGIES:
- Vaccination (antibodies)
- CAR T-cell therapy (special t-cells are programed to recognise cancer cells)
- Immune inhibitors (T-cells are more active in activating other immune cells)
- Cytokine therapy (Activates immune system to better destroy cancer cells)
- Monoclonal antibodies (Antibodies with specific target cells and cause immune response.)
Monoclonal antibodies
- New & commonly used to treat cancer
- MAbs = specifically designed antibodies (every antibody in a set binds to same antigen)
- Artificially produced (in lab stimulating B lymphocytes in mice injected with specific type of antigen)
STEPS:
1. Mouse injected with antigen and activates clonal selection & expansion of B lymphocytes -> antibodies produced
2. Spleen of mouse removed ( contains B cells)
3. B cells mixed & fused with myeloma cells (= tumour cell) so the B cell can divide indefinitely
4. Fused cells = hybridomas. These are cloned to have multiple copies
5. The selected clones can be grown indefinitely & the required antibodies can be harvested
How Monoclonal antibodies can be used for cancer
- Antibodies can be designed to target specific antigens and cancer cells.
- MAbs used in conjunction with other treatments (chemo/radio)
MODES OF ACTION:
Naked monoclonal antibodies:
- Stop growth of new blood vessels
- Signal immune cells to attack (cytotoxic T-cells)
- Block growth factors
Conjugated monoclonal antibodies:
- Deliver anticancer to cancer cells
Using MAbs for treating autoimmune disease
In autoimmune diseases, the body produces autoantibodies which attack the body’s self-cells
CANCER = MAbs used to Increase the immune response against cancer cells
AUTOIMMUNE = MAbs used to decrease the immune response against self-cells.
- The MAbs block the APC’s MHC-II marker which are trying to present the antigen of a body’s self-cell = T-Helper cell can’t bind to the MHC-II so immune response isn’t carried out.
