Infectious diseases are also known as communicable diseases or transmissible diseases. In medical terminology, infectious diseases are those diseases that are caused by the infection and growth of pathogenic biological agents in a host organism. At the same time, those infectious diseases that are easily transmitted from one host organism to another are termed as contagious diseases. Infectious diseases are caused by the interactions that occur between pathogens and the defense mechanism of the host organism. Pathogens can be broadly categorized as primary and opportunistic pathogens. Infectious diseases usually do not lead to the death of the patient and tend to cause mild to acute discomfort. The Indian population is often affected by a range of infectious diseases such as tuberculosis and dengue. Proper monitoring and improvement in health care services are the keys to tackle this widespread problem. Hide this