When is a person said to be suffering from a disease?

Select the correct option to fill up the blanks.
$(i)$ Diseases which are easily transmitted from one person to another,are called $.....$ diseases.
$(ii)$ In human body,parasite of malaria initially multiplies within the $........$ and then attack the $......$
$(iii) ......$ is the yellowish fluid secreted by mother during the initial days of lactation.
$(iv) ......$ and $.......$ are the primary lymphoid organs.

The Pulse-Polio programme is organised in our country:

Diseases present from birth are called . . . . . . .

The biological agents of disease include

Which of the following plays a role in preventing the entry of microorganisms into the body?