Question

Factors that affect the spread of epidemics - Part 1

Question: Explain the following statement:

Epidemiology is the Study of the relationship between an infectious agent and its host population

A balanced host/parasite relationship must exist:

The virus can deplete host, but if virus completely eliminates the host, it will become extinct.

Answer 1

Epidemiology is the Study of the relationship between an infectious agent and its host population

It is the branch of medical science that studies the factors that determine the presence or absence of diseases. In the above statement, the infectious agent could be a virus or a foreign body that could cause harm to the host (as in, the place where the infectious agent resides). This field of medicine studies how the presence or the number of infectious agents is important when compared to the host population for it to survive and continue residing in the host vessel.

A balanced host/parasite relationship must exist:

If there is a decreased number of infectious agents present in the host system, the antibodies in the host system are capable of eliminating the infectious agent thereby ending their presence.
If there is an increased number of infectious agents in the host system, it is possible for the host system to shut down thereby causing the end of the infectious agents too.
It is important that there is a balance in the host and parasite population so that the infectious agent survives and the antibodies fight against it.

The virus can deplete host, but if virus completely eliminates the host, it will become extinct.

This statement is an extension of the above point. If the virus depletes the host, the chances of recuperating are high and there are chances for the virus to continue to thrive in the host environment. If the virus eliminates the host, the host system is no longer available for the virus to reside and therefore is the end for the virus too.