TY - JOUR T1 - Extensively drug-resistant tuberculosis: back to the future JF - European Respiratory Journal JO - Eur Respir J SP - 475 LP - 477 DO - 10.1183/09031936.00025910 VL - 36 IS - 3 AU - G.B. Migliori AU - G. Sotgiu AU - C. Lange AU - R. Centis Y1 - 2010/09/01 UR - http://erj.ersjournals.com/content/36/3/475.abstract N2 - Tuberculosis (TB) has been found in mammoth bones and in Egyptian mummies. It has affected mankind since its appearance, despite many efforts to control and eliminate it.Epidemiology indicates that, in the absence of any intervention (e.g. under the natural history model), one infectious case is likely to infect ∼10 persons·yr−1 for 2 yrs, thus generating 20 infected individuals 1. Given that the lifetime breakdown is estimated to be 10%, and that ∼50% of cases are likely to become sputum smear-positive, one infectious source is likely to generate another infectious (sputum smear-positive) case 1. This is in the absence of intervention (fig. 1a). The interventions recommended by the directly observed treatment, short course (DOTS) strategy and the Stop TB Strategy 2 (e.g. rapid diagnosis of 70% of existing sputum smear-positive cases and effective treatment of 85% of cases) are very powerful in modifying this cycle (fig. 1b). The period of infectiousness is reduced by ≤6 months and the number of infected individuals is reduced to only five. Given the same breakdown rate and the same risk of developing a sputum smear-positive form of TB, one infectious case produces only a quarter the number of infectious cases of TB. In other words, it takes four infectious cases to produce one new one.Figure 1– Tuberculosis transmission model in a) the absence of control interventions and b) the application of early diagnosis and effective treatment. If the TB programme is able to reduce transmission so dramatically, one can expect a levelling off of the epidemic curve in a given setting after 5–7 yrs following implementation of the Stop TB Strategy. This has been demonstrated in countries such as Cuba and Peru. Recently it has been … ER -