Latent Pulmonary Tuberculosis: The Hidden Challenge in Tuberculosis Elimination

Latent Pulmonary Tuberculosis: The Hidden Challenge in Tuberculosis Elimination

                                                                                        dr. Putu Gita Indraswari, Sp.P

Tuberculosis remains a major public health burden in Indonesia. According to the Global Tuberculosis Report 2023 published by the World Health Organization, Indonesia is ranked second globally in terms of total tuberculosis incidence, trailing only India. Although national control programs have focused primarily on the identification and treatment of active tuberculosis, latent tuberculosis infection represents a critical yet frequently neglected component of the epidemic. Individuals with latent tuberculosis infection are infected with Mycobacterium tuberculosis but do not exhibit clinical symptoms and are not infectious. Nevertheless, they remain at risk of disease reactivation. Epidemiological studies estimate that approximately 5 to 10 percent of individuals with latent infection will progress to active tuberculosis during their lifetime, particularly when their immune function is compromised.

Latent tuberculosis infection occurs when host immune responses successfully contain the bacilli without eradicating them, allowing Mycobacterium tuberculosis to persist in a dormant state. Reactivation may occur at any point, particularly in populations with impaired immunity, such as people living with HIV, patients with diabetes mellitus, individuals receiving immunosuppressive therapies including post-transplantation or chemotherapy, as well as young children and the elderly. The World Health Organization estimates that approximately 25 percent of the global population is latently infected with tuberculosis. In Indonesia, it is projected that more than 60 million people are living with latent tuberculosis, representing a substantial and largely invisible reservoir that could contribute to future transmission.

Diagnosis of latent tuberculosis is based on immunological tests, namely the tuberculin skin test and the interferon gamma release assay. The tuberculin skin test, despite its longstanding use and accessibility, has limited specificity, particularly among individuals who have received prior Bacillus Calmette–Guérin vaccination. In contrast, the interferon gamma release assay provides higher specificity and is unaffected by BCG vaccination, but its cost and limited availability restrict its use in primary care settings in Indonesia. Although latent tuberculosis is not contagious, preventive treatment is indicated for individuals with increased risk of progression to active disease. Recommended treatment regimens include isoniazid for six to nine months, rifampicin for four months, or a combination of isoniazid and rifapentine administered weekly for three months. The latter regimen has demonstrated improved adherence and safety profiles in several high-income settings, although it remains largely unavailable in Indonesia.

The inclusion of latent tuberculosis management is essential for the success of the End TB Strategy proposed by the World Health Organization, which aims to eliminate tuberculosis as a public health threat by the year 2035. Focusing exclusively on active case detection and treatment is insufficient. A comprehensive national approach must also address latent infection, particularly among high-risk populations, through targeted screening, preventive therapy, and health system integration. Without addressing latent infection, Indonesia is unlikely to achieve its tuberculosis elimination targets. Therefore, latent tuberculosis must be recognized not only as a biomedical challenge but also as a strategic priority in national public health policy. Sustained investment in diagnostic infrastructure, professional education, and access to preventive treatment is essential to reducing the long-term burden of tuberculosis and progressing toward a tuberculosis-free Indonesia.

References:

1. World Health Organization. Latent tuberculosis infection: updated and consolidated guidelines for programmatic management. Geneva: World Health Organization; 2018. Available at: https://www.who.int/publications/i/item/9789241550239
2. World Health Organization. Global Tuberculosis Report 2023. Geneva: World Health Organization; 2023. Available at: https://www.who.int/publications/i/item/9789240071889
3. Centers for Disease Control and Prevention. Latent Tuberculosis Infection: A Guide for Primary Health Care Providers. Atlanta: CDC; 2023. Available at: https://www.cdc.gov/tb/publications/ltbi/default.htm
4. Ministry of Health, Republic of Indonesia. National Guidelines for Tuberculosis Control 2023. Jakarta: Ministry of Health; 2023. Available at: https://tbc.kemkes.go.id