[Tuberculosis: an ever present disease but difficult to prevent].

Tuberculosis (TB) is an infectious and contagious disease caused by Mycobacterium tuberculosis, commonly called Koch's bacillus. TB is spread by air and is present all over the world. Not everyone who become infected develop the disease; the immune system can cope with the infection and the bacterium can remain dormant for years. Despite advances in therapy and prevention, TB remains one of the top 10 causes of death worldwide. Over 9 million new cases and over 1 million deaths occur each year. Since 1921 BCG has been the only authorized vaccine. More than ten experimental vaccines are currently in different stages of development. Depending on the type, they are divided into vaccines consisting of: live attenuated, inactivated mycobacteria and subunits. According to their purpose they can be divided in: vaccines aimed at preventing infection, vaccines aimed at preventing disease, vaccines aimed at preventing recurrence and therapeutic vaccines. Hopefully, these numerous attempts to develop new vaccination approaches will lead to obtain products with greater immunogenicity and efficacy.