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.

Sputum smear examination and time to diagnosis in patients with smear-negative pulmonary tuberculosis in the Pacific.

SETTING: National tuberculosis programmes (NTPs) in Kiribati and the Marshall Islands, 2006-2010. OBJECTIVE: To determine the proportion of all tuberculosis (TB) cases that were pulmonary smear-negative, and for these patients to determine how many sputum smears were examined and the time from sputum smear examination to registration. DESIGN: A retrospective cross-sectional study involving a record review of national TB and laboratory registers. RESULTS: Of 2420 TB cases identified, 709 (29%) were registered as smear-negative pulmonary TB. Of the 695 (98%) with information on smear examination, 222 (32%) had no smear recorded, 61 (9%) had one smear, 86 (12%) two smears and 326 (47%) three smears. Among the 473 patients who had at least one smear, 238 (50%) were registered before sputum examination, 131 (28%) within 1 week, 72 (15%) between 1 and 4 weeks, and 34 (7%) >4 weeks after sputum examination. CONCLUSION: NTPs in Kiribati and the Marshall Islands are diagnosing 29% of all TB patients as smear-negative pulmonary TB. Many patients do not have smears done or are registered before undergoing smear examination. Corrective measures are needed.