active and passive + re-emergence Flashcards
what is active immunity?
when an individuals adaptive immune response responds to an antigen and produces specific antibodies, B and T cells and gains immunological memory
- requires involvement of individual adaptive immune system
- it is slow and develops overtime
how do you determine if the immunity is active or passive?
immunity is active or passive based on the origin of response
what is passive immunity?
short term immunity resulting from a person receiving antibodies produced from another organism/ the passive transfer of antibodies produced by another organism
- immediate response
- provides temporary protection
- transferred antibodies degrade overtime and are removed from the immune system
why is passive immunity lack long term immunity?
because the adaptive immune response won’t be activated and therefore no memory B and T cells will be created
what is are the types of immunity and acquisition of immunity?
types of immunity: active and passive
acquisition of immunity: artificial and natural
what is natural immunity?
natural immunity develops after natural encounters with a pathogen
what is artificial immunity?
develops after intentional introduction of antigens or antibodies into the body
what is natural active immunity?
an individuals response to a pathogen, that they produce specific antibodies for, that they have been exposed to. If individual were to encounter same pathogen in the future they would be immune to that pathogen because they have memory B and T cells
what is natural passive immunity?
passive transfer of antibodies from one organism to another that provides temporary protection -weeks or months.
- basically the transfer of antibodies from mother to foetus through placenta or through breastfeeding when the baby is born
what is active artificial immunity?
artificial active immunity is created when antigens or whole pathogens are intentionally introduced to induce an adaptive immune response (production of antibodies or memory B and T cells) through a vaccination for example
what is artificial passive immunity?
created when an individual receives antibodies or antiserum produced by another organism. Useful against bites that could cause death before an individuals adaptive immune response is activated
- transferred antibodies bind to antigens or toxins
- no immunological memory
- has time to suppress active immunity when it can be harmful
what is a vaccine?
material used to induce artificial immunity
what are the three types of vaccines?
live attenuated
inactive
subunit
what is a live attenuated vaccine?
contains weakened form of pathogen that causes the disease
- due to similarity between vaccine and natural pathogen, there is a strong adaptive immune response
- pathogen is still able to reproduce but not cause symptoms of the disease
- a single dose can initiate a strong adaptive immune response in those who are healthy but may cause disease in those with weakened immune systems
- can result in a lifetime protection against pathogen
- those with weakened immune systems may contract the disease
- live attenuated vaccines include measles mumps and rubella
what is an inactive vaccine?
uses a killed or non viable version of the pathogen
- the disease causing agent is unable to replicate
what are advantages of using an inactivated vaccine?
- results in production of many different antibodies as they contain different antigens
- safe for those with weak immune systems
disadvantages of inactivated vaccine?
- no life long immunity - therefore booster shots are needed in order to maintain long-term immunity by increasing memory B and T cell count
what is subunit vaccine?
uses specific pieces of the pathogen such as antigens, parts of antigens or a capsid: contains specific pieces of the pathogen selected for ability to induce an adaptive immune response
Those that contain multiple antigens induce broader immunity as they will induce production of antibodies against multiple antibodies
- examples include whooping cough and hepatitis B
what are advantages of subunit vaccine?
- safe for weak immune systems
- they are easier to store than live attenuated vaccines
what are disadvantages of subunit vaccine?
stimulates a weaker immune response therefore booster vaccines should be administered to maintain long term immunity
what characteristic should vaccines have?
vaccines need to be highly specific to the pathogen to initiate an adaptive immune response, resulting in immunological memory
what is herd immunity?
exists when a large amount of population has been immunised against a contagious disease through vaccination
- vital for immunisation programmes to be successful
- herd immunity slows spread of disease and protects those who aren’t immune
- if there is a widespread immunity in a population, there is little chance that infected person encounters someone not immune so the pathogen has very little opportunity to invade host as disease is not able to spread
- pathogen will die within an immune host before it can spread
what was the most immediate consequence of colonisation of Australia?
the wave of epidemic diseases including smallpox, typhoid, pneumonia, whooping cough and others
why weren’t Europeans affected by these diseases?
Europeans were resistant because they had already experienced these diseases but they annihilated native communities who had never been exposed
what factors made native people more susceptible to disease?
changes in diet: access to traditional food was restricted, rationing imposed, were forced to adopt European style of diet (high sugar and flour based)
change in lifestyle: nomadic lifestyle morphed to a more stationary lifestyle, they started living in one place instead of moving in groups (increasing exposure and spread of disease)
- illnesses caused by mental health or lifestyle choices can lead to reduced immune system function thereby increasing susceptibility to disease
what is the definition of infection?
occurs when pathogen has invaded the host by breaching first line of defence and started to replicate within the host
what is the definition of disease?
consequence of pathogen’s invasion, causing damage and impacting normal function of body’s tissues
definition of virulence?
likelihood that pathogen will cause disease and harm to a host once its in the body- how harmful the pathogen can be to you
definition of contagious
ability spread between individuals
definition of epidemiologist?
professionals who study the emergence or re-emergence of disease
what are emerging diseases?
a disease that has not occurred in humans before, or has occurred preciously but only affected a small number of people or has occurred throughout time but only recently been recognised as a disease
what is re-emergence of disease?
diseases that were once present and had dramatic decline in case numbers but have returned and are affecting a significant proportion of the population
examples of emerging diseases
HIV infections, west Nile disease, Lyme disease and ebola
examples of re-emerging diseases
influenza, malaria and tuberculosis
what are some reasons for emerging diseases? (7)
human behaviour and changes in human behaviour
- population growth
- international and domestic travel
- poverty
- ecological damage
- food supply chains
- intensive farming
- climate change
reasons for re-emerging diseases
- resistance or evolution of a pathogen
- drop in vaccination rates
how do bacteria acquire resistance?
bacteria can either mutate or exchange genetic material with other bacteria of the same or different species
what are consequences of mutation in bacterial genes?
- prevent drugs from adhering to their surface
- decrease permeability of their plasma membrane to drugs
- actively pump out the drug
- use enzymes that destroy actions of the drug
mutations in bacterial genes are less likely to be beneficial
what is conjugation?
a way that genetic material is exchanged between bacteria
how can conjugation occur?
pilus from one bacterium extends and joins that of another bacterium forming a bridge enabling plasmid DNA to be exchanged between the two bacteria. The plasmid could contain a gene that helps bacteria survive medications
how are so many bacteria becoming resistant?
both mutation and exchange are rare but widespread use of antibiotics is acting as a selection pressure driving evolution for stronger, more resistant pathogens.
more people are living closer together allowing easy exchange for pathogenic bacteria to live alongside non-pathogenic bacteria providing more opportunity to exchange genetic material and experience mutation from them
why can there be declines in vaccination rates?
when well established vaccination programmes become successful individuals may choose not to vaccinate
- can be fuelled by anti vaccination champagnes spreading invalid claims
how can you socially prevent spread of pathogens?
- promoting good hygiene
- requiring social distancing
- reducing movement of people via lockdowns
- wearing face marks
- encouraging people to get tested
- keeping healthy by eating a balanced diet and exercising regularly
- cleaning high touch surfaces
- sneezing and coughing in ways that reduce spread of aerosol droplets
what should epidemiologists understand before recommending particular control strategies?
- where infection originates from, transmission between hosts or involvement of any vectors
what are scientific ways to stop spread of pathogen?
- deep cleaning pathogen source or reservoir
- creation of vaccines to prevent infection
- drugs to prevent disease
- sanitation, hygiene education and social distancing
what are some public health measures to be maintained at all times to prevent spread of diseases?
- ensuring safe supply of water for drinking
- sewage treatment and disposal
- food safety and regulations
- food processing and farming
- border control of entry of exotic species
- pest and animal control
- vaccination programmes
- quarantine procedures
what is an endemic? pandemic? epidemic?
endemic: spread of disease contained to a specific geographical area
pandemic:
pandemic: when the growth rate of a disease is considered exponential and spread across a large geographical area
epidemic: unexpected increase in the number of disease in a specific geographical area
what is antigenic drift? how does it occur? how does it affect the immune system?
- occurs when small changes in the genes of viruses leads to changes in the surface proteins of the virus
- changes accumulate overtime
- results in viruses being closely related to one another, meaning they also have similar antigenic properties
- antibodies created by the immune system against one virus will most likely recognise and response to similar viruses
what is antigenic shift? what does it result in for the body?
antigenic shift is an abrupt major change in a virus resulting in new surface proteins and leading to a new virus strain.
- Can happen when a virus from an animal population gains the ability to infect humans.
- Surface proteins are different enough that most people don’t have immunity to the new virus
Why is antigenic shift worse than antigenic drift?
antigenic shift occurs more rapidly and results in more major changes than antigenic drift
