|Mycobacteriology is a sub-category of bacteriology which deals with all the species of mycobacterium such as mycobacterium avium, mycobacterium tuberculosis, mycobacterium paratuberculosis, etc. of all mycobacterium tuberculosis is the main causative organism of tuberculosis which affects human lung and leprosy which affects human skin. In animals, it causes mad-cow disease in animals. 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.