From the Guidelines
Latent tuberculosis (TB) is not contagious, as the bacteria are dormant and not actively multiplying, and therefore cannot spread from person to person through coughing, sneezing, or other airborne means. People with latent TB infection have the TB bacteria in their bodies, but the immune system has contained the bacteria, preventing them from causing illness or symptoms 1. However, it's essential to understand that latent TB can potentially develop into active TB disease if a person's immune system weakens due to factors like HIV infection, certain medications, or aging.
Key Points to Consider
- The lifetime risk of reactivation TB for a person with documented LTBI is estimated to be 5–15%, with the majority developing TB disease within the first 5 years after initial infection 1.
- Treatment for latent TB is recommended to prevent this progression and typically involves medications such as isoniazid (INH) for 6-9 months, rifampin for 4 months, or a combination of isoniazid and rifapentine for 3 months 1.
- These preventive treatments significantly reduce the risk of developing active TB disease, with an efficacy ranging from 60% to 90%, and the protection can last for up to 19 years 1.
Important Considerations for Treatment
- The potential benefit of treatment needs to be carefully balanced against the risk of drug-related adverse events 1.
- For infected individuals in population groups with a high risk of progression to active disease, the anticipated benefits are usually greater than the potential harms 1.
- Regular monitoring by healthcare providers is essential during treatment to check for any side effects from the medications.
From the FDA Drug Label
Isoniazid is recommended as preventive therapy for the following groups, regardless of age. Candidates for preventive therapy who have HIV infection should have a minimum of 12 months of therapy. 2. Close contacts of persons with newly diagnosed infectious tuberculosis (≥ 5 mm) In addition, tuberculin-negative (< 5mm) children and adolescents who have been close contacts of infectious persons within the past 3 months are candidates for preventive therapy until a repeat tuberculin skin test is done 12 weeks after contact with the infectious source.
The answer to whether latent TB is contagious is no, latent TB itself is not contagious, but individuals with latent TB can develop active TB, which is contagious. However, the fact that close contacts of persons with newly diagnosed infectious tuberculosis are candidates for preventive therapy suggests that there is a risk of transmission from someone with active TB to someone who may develop latent TB, and then potentially active TB. 2
From the Research
Latent TB Contagiousness
- Latent tuberculosis (TB) infection is not contagious, as it is an asymptomatic and non-infectious condition 3, 4, 5, 6, 7.
- Individuals with latent TB infection do not have active TB disease and therefore cannot spread the infection to others.
- The primary concern with latent TB infection is the potential for it to progress to active TB disease, which can be contagious.
Treatment and Prevention
- Treatment of latent TB infection is essential to prevent the development of active TB disease 3, 4, 5, 6, 7.
- Various treatment regimens are available, including isoniazid monotherapy, rifampin, and combination therapies such as isoniazid and rifapentine 3, 4, 6, 7.
- These treatment regimens have been shown to be effective in preventing active TB disease and have varying completion rates and safety profiles 3, 4, 6, 7.
Key Findings
- A 4-month regimen of rifampin was found to be non-inferior to a 9-month regimen of isoniazid for the prevention of active TB disease 3.
- A 3-month regimen of isoniazid and rifapentine was associated with higher treatment completion rates compared to a 9-month regimen of isoniazid 6, 7.
- The 3-month isoniazid-rifapentine regimen was found to be as safe and effective as other recommended latent TB infection regimens and achieved significantly higher treatment completion rates 7.