Mass treatment to eliminate tuberculosis from an island population

SETTING: The global target of tuberculosis (TB) elimination by 2050 requires new approaches. Active case finding plus mass prophylactic treatment has been disappointing. We consider mass full anti-tuberculosis treatment as an approach to TB elimination in Kiribati, a Pacific Island nation, with a persistent epidemic of high TB incidence. OBJECTIVE: To construct a mathematical model to predict whether mass treatment with a full course of anti-tuberculosis drugs might eliminate TB from the defined population of the Republic of Kiribati. METHODS: We constructed a seven-state compartmental model of the life cycle of Mycobacterium tuberculosis in which active TB disease arises from the progression of infection, reinfection, reactivation and relapse, while distinguishing infectious from non-infectious disease. We evaluated the effects of 5-yearly mass treatment using a range of parameter values to generate outcomes in uncertainty analysis. RESULTS: Assuming population-wide treatment effectiveness for latent tuberculous infection and active TB of ≥90%, annual TB incidence is expected to fall sharply at each 5-yearly round of treatment, approaching elimination in two decades. The model showed that the incidence rate is sensitive to the relapse rate after successful treatment of TB. CONCLUSION: Mass treatment may help to eliminate TB, at least for discrete or geographically isolated populations.