Infectious diseases are caused by microbial organisms, like viruses, bacteria, fungi and even parasites. Most of these organisms live within the body and do not cause harm. However, they might become harmful in certain conditions and spread diseases. While some of the diseases are spread from person to person, some can be spread by animals and insects. Infectious diseases can even be spread from contaminated food and water. You would get proper care in the clinic and the doctor would offer the necessary treatment procedures.