Attenuate: To decrease the
virulence of a pathogen and render it incapable of causing disease. Many
vaccines are composed of attenuated bacteria or viruses that induce protective
immunity without causing harmful infection.
"Some live vaccines are attenuated by growing them in cells in which they don’t reproduce very well, this hostile environment makes the virus weaker. "
Herd immunity: When the majority of the population is immune to an infectious agent, thus significantly reducing the pathogen reservoir due to the low chance of a susceptible individual.
"Due to the herd immunity for small pox, if one decides to not get vaccinated for the disease it is very likely that you will still be protected from acquiring the disease thanks to your neighbor’s immunity. "
Pathogen: A disease causing infectious agent
"In third world countries it is very common for children and adults to have parasitic pathogens in their intestines due to the poor nutrition and poor living conditions."
Tolerance: A state of immunological unresponsiveness to particular antigens or sets of antigens.
"In order for our immune system to function properly and not fight against itself in an immune response it must be tolerant to self-antigens."
