About a hundred years ago, when smallpox persisted, a group of people who had
this disease earlier and had survived it had no chance of suffering from it again. So
having the disease once was a means of preventing subsequent attacks of the same
disease.
i) Why does this happen? Explain.
ii) We can fool the immune system. Clarify
iii) Name this principle of prevention of disease.
Answers
Answer:
a) If we have small pox once, there is no chance of suffering from it again because when the immune system first sees an infectious microbe, it responds against it and then remembers it specifically. When the next time, the same particular microbe or it's close relative enters the body, the immune system responds with more vigour. This eliminates the infection even more quickly than the first time around.
b) We can fool our immune system into developing a memory for a particular infection by putting something, that mimics the microbe we want to vaccinate against, into the body. This does not actually cause the disease but this would prevent any subsequent exposure to the infecting microbe from turning into actual disease.
c)The principle of prevention of diseases is called vaccination.