What is the difference between latent tuberculosis (TB) and active tuberculosis (TB)?

From the Guidelines

Latent tuberculosis should be distinguished from active tuberculosis through systematic testing and treatment, as recommended by the World Health Organization guidelines for low tuberculosis burden countries 1. The key difference between latent and active tuberculosis lies in the presence or absence of symptoms and the ability to transmit the disease. Latent tuberculosis infection (LTBI) is characterized by the presence of immune responses to previously acquired Mycobacterium tuberculosis infection without clinical evidence of active tuberculosis (TB) 1.

Key Considerations

• Testing for LTBI involves either commercial interferon-gamma release assays or Mantoux tuberculin skin testing, as recommended by the World Health Organization guidelines 1.
• Chest radiography should be performed before LTBI treatment to rule out active TB disease 1.
• Recommended treatment regimens for LTBI include: 6 or 9 month isoniazid; 12 week rifapentine plus isoniazid; 3–4 month isoniazid plus rifampicin; or 3–4 month rifampicin alone, as outlined in the guidelines 1. In contrast, active tuberculosis occurs when the bacteria overcome the immune system and multiply, causing symptoms such as persistent cough, chest pain, weight loss, night sweats, and fever.

Treatment Approaches

• Treatment for active TB requires a combination of multiple antibiotics (typically isoniazid, rifampin, ethambutol, and pyrazinamide) for at least 6 months, often with directly observed therapy to ensure compliance.
• The distinction between latent and active TB is crucial because treatment approaches differ significantly, with active TB requiring more aggressive and prolonged therapy to cure the infection and prevent transmission. Systematic testing and treatment of LTBI is strongly recommended in high-risk individuals, including people living with HIV, adult and child contacts of pulmonary TB cases, and patients with certain medical conditions, as outlined in the World Health Organization guidelines 1.

From the FDA Drug Label

1. 2 Latent Tuberculosis Infection PRIFTIN is indicated in adults and children 2 years and older for the treatment of latent tuberculosis infection caused by Mycobacterium tuberculosis in patients at high risk of progression to tuberculosis disease

2. 1 Active Pulmonary Tuberculosis PRIFTIN® (rifapentine) is indicated in adults and children 12 years and older for the treatment of active pulmonary tuberculosis (TB) caused by Mycobacterium tuberculosis.

The main difference between latent tuberculosis and active tuberculosis is that latent tuberculosis is an asymptomatic, non-transmissible infection, whereas active tuberculosis is a symptomatic, transmissible disease.

• Latent tuberculosis requires treatment to prevent progression to active disease, and PRIFTIN is indicated for this purpose in patients at high risk of progression.
• Active tuberculosis requires treatment with a combination of antituberculous drugs, including PRIFTIN, to cure the disease. The treatment regimens for latent and active tuberculosis differ, with latent tuberculosis typically treated with a 12-week once-weekly regimen of PRIFTIN in combination with isoniazid, while active tuberculosis is treated with a 2-month initial phase followed by a 4-month continuation phase, using PRIFTIN in combination with other antituberculous drugs 2.

From the Research

Latent Tuberculosis vs Active Tuberculosis

• Latent tuberculosis infection (LTBI) is a condition where a person is infected with Mycobacterium tuberculosis, but does not show any symptoms of active tuberculosis (TB) disease 3, 4, 5, 6.
• Active tuberculosis, on the other hand, is a condition where the person shows symptoms of TB disease, such as coughing, fever, and weight loss 4.
• The treatment of LTBI is an important component of TB control and elimination, as it can prevent the development of active TB disease 3, 4, 5, 6.
• The treatment regimens for LTBI include once-weekly isoniazid plus rifapentine for 3 months, daily rifampin for 4 months, daily isoniazid plus rifampin for 3-4 months, and daily isoniazid for 6-9 months 3, 4, 6.
• First-line therapy for active tuberculosis has remained unchanged for nearly 40 years, and includes isoniazid, rifampin, pyrazinamide, and ethambutol for the initial two-month phase, followed by isoniazid and rifampin for 4 to 7 months 4.

Treatment Comparison

• A systematic review and meta-analysis found that 3-month isoniazid-rifapentine was as effective as other LTBI regimens, and had higher treatment completion rates (87.5% vs 65.9%) 5.
• Another study found that rifamycin-based regimens for LTBI were successful in preventing progression to TB disease, and that once-weekly isoniazid and rifapentine for 12 weeks was safe and effective compared to 9 months of isoniazid 4.
• A translational pharmacokinetic-pharmacodynamic modeling study found that a 6-week rifapentine monotherapy regimen (6wP) may be as effective as, or even more effective than, the currently recommended 1-month or 3-month isoniazid-rifapentine regimens for LTBI treatment 7.

Treatment Outcomes

• The treatment outcomes for LTBI and active TB disease are different, with LTBI treatment aiming to prevent the development of active TB disease, and active TB disease treatment aiming to cure the disease 3, 4.
• The efficacy of LTBI treatment regimens can be measured by the reduction in the risk of developing active TB disease, while the efficacy of active TB disease treatment regimens can be measured by the cure rate and the reduction in morbidity and mortality 4, 6.