To eliminate tuberculosis, we must universally encourage treatment of its latent form

Field: Medicine (Health Sciences)

In a recent editorial in this journal, a strong case was made for strengthening the role of treating latent tuberculosis in achieving elimination of tuberculosis.1 The writer reminded us of the slow progress in achieving global tuberculosis control using current strategies as well as reminding us of the safety and efficacy of treating latent tuberculosis (especially when combined with improved tools for both diagnosis and treatment). It was correctly recognized that latent infection precedes active disease and that often active disease was spread after infection has been transmitted. However, there seems to be an implication (perhaps unintentionally) that treatment of active disease fails because infection has already been transmitted before diagnosis and because treatment renders active disease non-infectious very quickly. It is important to appreciate that effective treatment (meaning the use of a regimen that will cure the active disease component and prevent any future risk of reactivation) is important in any strategy to control tuberculosis. Much of the failure to control tuberculosis globally is due to the failure to achieve this, either because many people still do not have access to timely diagnosis or because many people are not given an effective regimen (as evidenced by the rate of drug-resistant tuberculosis and treatment failure and early reactivation disease) in many parts of the world. Failing to treat tuberculosis effectively results in chronic cases that continue to transmit tuberculosis and that results in forms of tuberculosis that are more difficult to treat (resulting in greater difficulty for interruption of transmission). After the introduction of effective treatment, tuberculosis rates in many places with effective services that ensured access to effective treatment and full case holding to completion of full courses of treatment saw dramatic falls in tuberculosis rates. When this was combined with improved social conditions, the chances for secondary transmission prior to diagnosis declined significantly, and in some places tuberculosis approached elimination although this became threatened by the mass displacement of people that began to occur from the late 1970s and has continued to occur since. In Queensland, Australia, over my more than 35 years working in tuberculosis control, I have seen dramatic falls in the rate of tuberculosis, and in recent years there has been little evidence for transmission. Where significant transmission has occurred, this has usually been in populations that rarely access health-care services, and transmission has been interrupted by working with these communities and improving access to health services. Until this work is done, there are both delays in diagnosis of active disease and a lack of access to preventive services such as better screening and treatment for latent infection. It is difficult to deny that treatment of latent infection is important in the overall control of tuberculosis, most importantly there is a need to improve access for all people to effective health services that will ensure early diagnosis and effective treatment. Once this is set up, treatment of latent tuberculosis will be an important part of the total care of these people.