TB & Leprosy
in the Pacific
Tuberculosis (TB, caused by Mycobacterium tuberculosis) is a leading infectious disease killer globally and in the Pacific, while leprosy (caused by Mycobacterium leprae) elimination remains a major challenge as well.
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Historical population-wide TB elimination programmes demonstrated considerable success in reducing TB incidence, with specific emphasis on active case finding and prevention strategies. Modelling projections suggest that this effect, and its durability, can be enhanced by concurrent treatment of latent TB infection, but data on ‘real-life’ implementation remain scarce.
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The PEARL study is designed to generate this missing – and world-changing – data.
Kiribati
South Tarawa
At the 2020 census, around 59% of the i-Kiribati population lived on the capital atoll of Tarawa. Of all TB cases detected in Kiribati in 2019, 76% (319 of 419) were from Tarawa - equating to a TB incidence of >500/100,000 population, the threshold incidence level above which the WHO recommends population-wide screening interventions. M. tuberculosis strain typing data and the dominance of young adults among TB cases indicate high levels of community transmission, which emphasises the need for case finding and prevention strategies to be combined in order to prevent rapid re-infection.
Leprosy rates in Kiribati, and South Tarawa in particular, are also among the highest in the world (>200 cases/100,000 population, compared to the WHO elimination threshold of 10/100,000 population) and have been rising rapidly after a nadir in the late 1990s when elimination efforts were discontinued. Modelling studies done in Kiribati indicate that a single population-wide active case finding intervention, combined with ‘universal leprosy prophylaxis’ using single-dose rifampicin, could dramatically decrease leprosy prevalence with a sustained effect.
Although both TB and leprosy pose daunting public health challenges in this resource-limited setting, their co-occurrence within a geographically defined and isolated population presents a unique opportunity to evaluate combined elimination efforts.
The aim of the PEARL study is to achieve major reductions in TB and leprosy incidence and transmission in Tarawa over the medium term, providing a pathway to future elimination. If successful, the PEARL study will provide a template for TB and leprosy elimination efforts throughout the Pacific and in other remote settings.
