The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years. Disease is an abnormal condition of an organism that will exhibit specific symptoms and affects regular metabolism. It may be caused by external factors generally referred as foreign particles and will produce infectious diseases. These foreign particles will act as antigens, which will react with our immune system and finally leading to disease condition. Sometimes diseases will be produced by internal dysfunctions, which will lead to autoimmune diseases. Infectious diseases are transmissible diseases and these transmissible diseases will spread or transmit from one person to the other and will become more resistant. Some of the infectious diseases include measles, syphilis, tuberculosis, etc. Auto immune diseases will not spread through any external factor and these diseases generally produce by our own body and sometimes these autoimmune diseases will lead to death. Some of the auto immune diseases include autoimmune hemolytic anemia, addison's disease, berger's disease, etc.