The Global TB report 2023 indicated that two-thirds of global TB cases in 2022 were concentrated in eight countries: India, Indonesia, China, the Philippines, Pakistan, Nigeria, Bangladesh, and the DRC [4]. Achieving the WHO’s goal of eradicating TB requires effective control of its spread in these eight countries. This study aims to address this limitation and provide a comprehensive analysis of the TB situation in these high-burden countries using GBD 2021 data. It is important to note that although the GBD 2021 data used in this study employs different estimation methods compared to those of the WHO, the estimates are consistent [13].

The study found that young people in India, the Philippines, Pakistan, and Bangladesh are at a high risk of developing TB. Individuals in this age group play a crucial role in national development, societal progress, and family responsibilities. Their higher levels of activity compared to other age groups increase their exposure to TB patients, potentially leading to more frequent outbreaks within families, schools, and workplaces. Therefore, strengthening the management of TB patients in these countries is crucial, with identifying and screening individuals with TB from the general population being the top priority. However, the health resources available in Southeast Asia are insufficient for effectively managing TB cases [22]. There is an urgent need for a substantial increase in investment in TB prevention, diagnosis, care, and treatment to avoid the potentially disastrous consequences for the region. Additionally, this study revealed that TB incidence in China and Indonesia primarily affects the elderly population. These countries have a significant proportion of elderly individuals, and the aging trend has been steadily increasing in recent years [23, 24]. The demographic shift may be a crucial factor contributing to the higher incidence. Moreover, this study has identified a risk of TB among the younger age group (around 20 years old) in both countries, consistent with Zhe’s finding [7]. Therefore, TB prevention and control efforts in these countries should prioritize both adolescents and the elderly, with a focus on enhanced screening, prompt case detection, and early treatment. In contrast, our findings indicate that the incidence of TB in two African countries, Nigeria and the DRC, is notably high among children under 5 years old. This issue may be linked to insufficient vaccination efforts. Previous studies [25,26,27] highlight significant challenges in Africa’s vaccine production capacity, such as a shortage of trained personnel, inadequate public health infrastructure, limited access to maternal health facilities, unreliable information, and deep-rooted cultural beliefs that hinder vaccination efforts. Therefore, it is imperative for African leaders to actively promote vaccine development, while governments and the media should enhance public awareness and understanding of the benefits of vaccination. The second United Nations High-Level Meeting [28] on TB emphasized the longstanding neglect of children and adolescents by global and national policymakers, researchers, and manufacturers of TB diagnostic tools and treatments. It highlighted the urgent need to take decisive measures to mitigate the detrimental impact of TB on children and adolescents.

The ASIR and risk of TB has shown a downward trend over the past 30 years in most countries, although the rate of decline has slowed recently, potentially due to the impact of the COVID-19 pandemic. However, progress has fallen significantly short of the WHO targets, which aimed for a 20.0% reduction in TB incidence by 2020 compared to 2015 levels, and a 50.0% reduction by 2025. The setback caused by the COVID-19 pandemic has further complicated the achievement of these goals [2]. Notably, both the Philippines and the DRC have experienced an increasing trend in the incidence and RR of TB in recent years. The Philippines achieved nationwide coverage of directly observed treatment, short-course therapy in 2003. The national TB control program has become increasingly proactive. Since 2008, the management of drug-resistant TB has been integrated into the national TB plan [29, 30]. Since 2012, the implementation of the TB detection project in Palawan province has significantly improved TB reporting rate [31]. In the DRC, the National TB Control Center acquired GeneXpert devices in 2013, which have been widely used in rural areas. Since then, the number of detected TB cases has increased. Additionally, Rwanda established a TB/HIV collaboration mechanism at the central level through the Ministry of Public Health from 2004 to 2009, facilitating routine TB screening for HIV patients receiving antiretroviral therapy [32]. Furthermore, the Ebola virus disease outbreak in the DRC between 2018 and 2020 led to a misallocation of national health resources, resulting in the neglect of TB and contributing to a surge in new TB cases in recent years [33].

Cohort effects have revealed that the RR of developing TB was higher among individuals born before 1960 compared to those born later in eight high-burden TB countries. This suggested that screening, diagnosis, and treatment of TB should maintain vigilance, especially for older individuals. Among these countries, Indonesia and Nigeria also exhibited a higher risk of TB among middle-aged individuals (RR > 1.0), with smoking potentially being a contributing factor [34]. According to Indonesia’s basic health study data from 2018, 33.8% of individuals aged 15 and older were smokers. Co-infection or comorbidity with other pathogens or diseases, such as AIDS, diabetes and silicosis may also be significant factors, as these conditions are more prevalent among middle-aged and elderly individuals [35, 36]. Our research has also identified a concerning trend in the Philippines and Pakistan, where the risk of developing TB has gradually increased as more recent birth cohorts are considered since 1990. This indicates that individuals born in more recent years are becoming more susceptible to TB, particularly in the Philippines, where the RR has been greater than 1 since 2011. Previous studies have also highlighted that a significant proportion (27.3%) of TB patients in the Philippines fall within the age range of 0–24 years [37]. In Pakistan, approximately 369,000 TB cases were reported in 2018, with children accounting for 13.0% of these cases, accompanied by a high rate of under-reporting [38]. Several factors contribute to this phenomenon. First, individuals aged 10–24 years often spend prolonged periods in densely populated environments, such as schools, which greatly increases the risk of transmission. Additionally, there has been a notable increase in HIV infection rates among young people, with less than half of these individuals receiving antiretroviral therapy, thus significantly increasing their vulnerability to TB compared to those receiving treatment [35]. Half of the country’s population is under the age of 25, which is a significant factor in the increased risk of disease among young individuals [39]. Regarding TB control, other research [40, 41] has emphasized the need to focus not only on screening, diagnosis, and treatment but also on adopting a comprehensive grassroots approach that provides social protection to vulnerable groups and young individuals. Effective TB interventions in the Philippines should prioritize those most affected by the disease, including individuals living in overcrowded slums, economically disadvantaged populations lacking access to education and healthcare, individuals experiencing severe prison overcrowding, and young people living with HIV who do not have access to antiretroviral treatment. Additionally, underreporting of TB remains a significant concern in Pakistan. The childhood TB program implemented under the Zero TB initiative has been crucial in identifying unreported cases, and it is essential to sustain this program moving forward [42].

This study predicts that by 2030, the completion rate of the eight high-burden countries toward the WHO target will be less than 50.0%. Simultaneously, they are unlikely to meet the TB control targets set by their respective countries [7, 9, 22, 29, 32, 37]. Specifically, the incidence of TB in the Philippines is expected to continue to rising, while in India and Indonesia, the completion rate is projected to be less than 20.0%. Several factors affect the achievement of this goal, which this study analyzes as follows: gross domestic product (GDP) per capita and the prevalence of undernourishment are closely associated with TB incidence [2, 4]. In 2022, sub-Saharan Africa’s GDP (USD 2.1 trillion) and GDP per capita (USD 1701.2) were lower than the rest of the World Bank subregion [43]. According to the Food and Agriculture Organization [44], over 200 million individuals experienced undernourishment in sub-Saharan Africa during 2014–2016. The prevalence of undernourishment in this region rose from 181 million in 2010 to 222 million in 2016. Poverty is a primary cause of hunger and malnutrition in Africa, further contributing to the rise in diseases across the continent [45]. Furthermore, ambient air pollution is rising throughout Africa, posing significant threats to health, human capital, and economic development [46]. At the same time, the South Asia’s GDP was only slightly higher than that of sub-Saharan Africa [43], suggesting that the high levels in these regions are likely due to poverty and malnutrition. Therefore, effectively addressing issues such as malnutrition and exposure to air pollution may accelerate progress toward achieving these goals. An Indian study [47] revealed that, despite the availability of free diagnostic and treatment services under a national TB control program, households affected by TB faced a high risk of catastrophic costs and further impoverishment, highlighting the urgent need for additional financial protection for TB patients. A large population base is another challenge for effective TB control. According to the Chinese Bureau of Statistics [48], China’s population was projected to reach 1.4 billion in 2021, making it the largest in the world. Although China has made progress in reducing TB deaths and incidence rates over the past three decades [49], it is still far from meeting the targets set by the WHO’s End TB Strategy for 2030. It is worth emphasizing that China’s aging population is projected to continue accelerating. If effective control of TB among the elderly is not achieved, some of the aging countries, including China, may experience higher TB incidence than currently predicted.

This study has several limitations. Firstly, the data used in this study are based on GBD 2021, which provides estimated values. However, it is important to note that these estimates closely align with the figures reported by the WHO. Second, the study only performed a status analysis of the eight high-burden TB countries in the results section, without examining the risk factors. Third, the prediction model used in this study relies solely on time trends and does not account for the influence of multiple factors on the disease. Notably, environmental changes, the prevalence of other diseases, population aging, and updates to vaccines may all significantly impact forecast results; therefore, these results should be considered as preliminary references only.