Urban and rural prevalence of tuberculosis in low- and middle-income countries: a systematic review and meta-analysis

Background

Urban and rural settings differ in key determinants of tuberculosis (TB) burden, including transmission dynamics, social and structural determinants, and healthcare access. However, understanding of urban and rural TB burden is limited, hindering implementation of public health interventions to end TB.

Methods and Findings

We conducted a systematic review and meta-analysis of urban and rural differences in adult pulmonary TB prevalence in low- and middle-income countries between 1993 and 2024. Bayesian multilevel meta-regression was used to estimate pooled urban-to-rural prevalence ratios (PR) for bacteriologically-confirmed and smear-positive TB overall, and by World Health Organization (WHO) region. We also stratified analysis by survey-level risk of bias and TB screening algorithm, investigated time trends, and evaluated associations with country-level TB incidence and population proportion living in urban areas. To estimate the number of people with prevalent TB in urban and rural areas in study countries, and how these have changed between 2000 and 2023, we fitted a Bayesian multivariate model to WHO incidence and case detection ratio data and combined these estimates with assumptions about the duration of treated and untreated TB and the distribution of urban and rural populations.

We included 46 surveys conducted between 2000 and 2019, encompassing 2,331,775 participants. The pooled urban-to-rural prevalence ratio of bacteriologically-confirmed TB was 1.08 (95% credible interval [CrI]: 0.87-1.33) and was 1.21 (95% CrI: 0.92-1.57) for smear-positive TB. However, there were substantial differences between WHO regions: the African Region had higher urban bacteriologically-confirmed prevalence (PR: 1.29, CrI: 1.01–1.61), while the Western Pacific Region had higher rural prevalence (PR: 0.64, CrI: 0.45–0.89), and burden was broadly similar in the South-East Asia Region (PR: 0.86, 95% CrI: 0.64-1.10). Time trends indicated a small increase in the overall bacteriologically-confirmed urban-to-rural prevalence ratio between 2000 and 2019, with a mean PR increase of 2.2% (95% CrI: -2.5 to 8.0%) per year.

We estimated that, for 2023 in the 26 represented study countries (combined population: 2.2 billion urban, 2.4 billion rural), 47% (95% CrI: 34-62%; 6.5 million, 95% CrI: 3.6-11.8 million) of prevalent TB was in urban areas, and 53% (95% CrI: 38-66%; 7.3 million, 95% CrI: 4.2-12.8 million) in rural areas. Within countries, there were striking changes in the urban and rural distribution between 2000 and 2023, with the share of urban cases increasing in nearly all countries.

Conclusion

Between 2000 and 2023, TB epidemics have become increasingly urbanised, both in proportional and absolute terms, although with considerable variation across countries and regions. Public health approaches tailored to urban and rural TB epidemiology and demography will be required to end TB.