Is old pulmonary tuberculosis contagious?

　　The human body has an extremely complex structure, including the lungs. The lungs are a vital part of the respiratory system; thus, pulmonary infections causing disease can significantly impact a patient’s health. Tuberculosis (TB) is a common infectious disease. To prevent it, one must first understand its etiology. So, is inactive pulmonary tuberculosis contagious?

　　Is Inactive Pulmonary Tuberculosis Contagious?

　　Inactive pulmonary tuberculosis is not contagious. It refers to residual scar lesions left behind after a prior TB infection has been treated with anti-tuberculosis medications and the active lesions have resolved. These old lesions typically appear stable on chest X-rays. However, latent Mycobacterium tuberculosis may persist within these old lesions, making them a potential source of secondary (reactivated) pulmonary tuberculosis. When host immunity declines—such as during concurrent illness or immunosuppression—the delicate balance between immune defense and bacterial virulence may be disrupted, leading to disease reactivation.

　　Inactive pulmonary tuberculosis represents fibrotic changes remaining after clinical improvement—either following treatment or spontaneous resolution—of pulmonary TB. Some of these lesions may undergo calcification. Inactive pulmonary tuberculosis denotes a stable, non-infectious form of TB that generally requires no specific treatment or curative intervention. Such lesions often remain unchanged for years and usually cause no symptoms. Nevertheless, a small proportion of patients may experience TB reactivation, presenting with symptoms such as cough, low-grade fever in the afternoon, and night sweats.

　　In daily life, maintain a regular, balanced diet; avoid spicy, irritating foods, overeating, and staying up late. We hope this information is helpful to you.