Key Knowledge 9 Flashcards
infectious disease
an illness caused by a pathogen that can be transmitted between individuals
pathogen
an agent that causes disease
re-emerging disease
an infectious disease that was previously under control but that is now increasing in incidence
emerging disease
an infectious disease that is new to the human population, or that is rapidly increasing in incidence
Evolution of causative organism
The pathogens causing disease can evolve to either infect humans or, if previously capable of infecting humans, evolve to evade treatments by acquiring resistance.
Globalisation and travel
Due to our ability to quickly travel around the world, diseases that would otherwise have remained localised to a specific area can quickly spread to multiple countries
Increased exposure of humans to animals
As the human population grows and climate change alters the environment, humans are more likely to come into contact with animals. A zoonosis is a disease caused by a pathogen that has been transmitted to humans from another species.
Increasing human population
Larger populations lead to increased population densities in cities, increasing the likelihood of a disease spreading and causing large scale health problems for a population.
Changing technology
Sometimes new technology can be responsible for the emergence or re-emergence of a disease. For example, Legionnaires’ disease is caused by a pathogen that inhabits air conditioning systems.
Insufficient vaccination of the population
Previously managed diseases can re-emerge if the proportion of a population that is vaccinated against the disease decreases. This stems from the loss of herd immunity, with an increase in the number of susceptible individuals allowing the pathogen to more easily spread between individuals.
epidemic
a dramatically increased occurrence of a disease
in a particular community at a particular time
pandemic
an epidemic that has spread across multiple countries and/or continents
Physical method of identifying pathogens
Visualising pathogens using microscopes to determine their structure
Phenotypic method of identifying pathogens
Selective media – an agar plate designed to allow certain pathogens to grow and multiply to test for their presence in a sample
Biochemical test panels – a series of tests designed to specify a sample’s genus and species.
Immunological method of identifying pathogens
Serology – the diagnosis of disease based on the presence of antibodies or antigens in a person’s serum. One example used to detect the presence of pathogenic antigens in a sample is the enzyme-linked immunosorbent assay (ELISA). There are four main
types of ELISA tests – direct, indirect, sandwich, and competitive.
Molecular method of identifying pathogens
Hybridisation-based detection – labelled segments of genetic material that are complementary to a pathogen’s genetic material are added to a sample. If a signal is generated, it means a pathogen is present.
Whole-genome sequencing – provides detailed information about the pathogen.
Airborne transmission
Pathogens spread via very small particles that stay in the air for prolonged periods of time
Droplet transmission
Respiratory droplets containing pathogens can remain suspended in the air for a short period of time, before falling to the ground/onto a surface.
Direct physical contact transmission
Pathogens can spread when a host physically touches another individual.
Indirect physical contact transmission
Indirect transmission occurs when there is no direct host-to host contact. Pathogens are spread between hosts via food, water, tissues, needles
Faecal-oral transmission
Pathogens excreted in faeces can end up being consumed by another person indirectly via contamination of food or water by infected faeces.
Prevention
- Improving hygiene
- Use of antiseptics and disinfects
- Access to clean water and food
- Personal protective equipment
- Vaccination
- Lockdown
Screening
- Routine testing
- Observe medication sales
quarantine and isolation
- Separate infected from healthy people
Identification of the Pathogen
Identify which pathogen is present in an individual so they can initiate the appropriate responses
Treating infected individuals
Specific curative treatment, including the use of medications such as antibiotics and antivirals to target the pathogen
immunotherapy
medical interventions that treat disease by modulating the immune system, typically by either amplifying or reducing an immune response
chimeric
an organism or cell containing genetic material from
another organism or cell
monoclonal antibodies (mAbs)
identical laboratory-made antibodies produced by plasma cell clones
autoimmune disease
a disease in which an individual’s immune system initiates an immune response against their own cells
B lymphocyte
a type of lymphocyte that plays an important role in humoral immunity and differentiates into plasma cells and B memory cells
myeloma cells
rapidly-dividing cancerous plasma cells which are fused with extracted B cells from mice to produce hybridomas
hybridoma
the product of the fusion between a mouse’s extracted plasma cell and a myeloma cell
naked monoclonal antibodies
monoclonal antibodies that do not have any other molecules attached to them
conjugated monoclonal antibodies
monoclonal antibodies with other molecules (e.g. chemotherapy drugs or radioisotopes) attached to them
complement proteins
a number of different types of proteins found in the blood that opsonise, cause lysis, and attract phagocytes to invading pathogens
membrane attack complex (MAC)
a pore formed by complement proteins in the cell membrane of a pathogen, disrupting the membrane and leading to the pathogen’s destruction
apoptosis
the controlled death of cells in the body. Also known as programmed cell death
autoantibodies
antibodies directed against an organism’s own tissues
immunosuppression
a reduction in the ability of the immune system to generate an immune response
immune deficiency
a state in which the immune system is no longer able to protect the body against infection or disease. Also known as immunodeficiency
autoreactive
a cell that recognises a self-tissue or self-antigen as non-self
Process of producing monoclonal antibodies
- Selection of antigen
- Vaccination of mouse
- Extraction of mouse B cells
- Fusion of mouse B cells with myeloma cells to create hybridomas
- Selection of appropriate hybridoma
- Collection and purification of antibodies
