Latent tuberculosis infection (LTBI) occurs when a person is infected with the Mycobacterium tuberculosis bacteria but does not show any symptoms of active tuberculosis (TB). The immune system can control the bacteria, preventing them from multiplying. People with LTBI are not contagious and cannot spread the infection to others. However, LTBI can become active TB if the immune system weakens, leading to symptoms like cough, fever, and weight loss. Screening and treatment for LTBI are important to prevent the development of active TB, especially in high-risk populations.