The three methods to control communicable diseases are isolation, quarantine and vector control. The most effective method to control communicable diseases is to control the vectors that transmit diseases among people. Although isolation is the best method, it requires potentially infected individuals to be identified early enough to make it effective. This can be difficult as many infected people will not seek treatment until after they have already infected others, and carriers are also problematic as they infect others without exhibiting any symptoms. Using quarantine is hampered by the same difficulties in identifying infected individuals and it is also difficult to impose quarantine.
Tuberculosis is considered a persistent infectious disease due to the increased numbers of infected individuals who have harboured the disease for most of their lives. It is also considered a re-emerging infectious disease, as at one time it was thought to have been effectively wiped out through treatment with antibiotics, but is now making a comeback due to the rise of antibiotic resistance.