Because tuberculosis is contagious and more easily transmitted to those in close contact with the patient, close contacts of patients with infectious tuberculosis (smear-positive tuberculosis) should be screened for earlier detection of tuberculosis infection and earlier treatment. For close contacts of infectious TB patients, such as relatives or colleagues, especially whether these relatives or colleagues have developed suspicious symptoms of TB with coughing and sputum production for more than 2 weeks, if suspicious symptoms have developed, screening for TB should be actively performed. Close contacts who do not have suspicious symptoms, especially children, can also be tested for Mycobacterium tuberculosis infection by performing a tuberculin test. For some special populations, even if they are asymptomatic, they can be treated prophylactically with a short course of medication if they are clearly infected with the bacillus. These groups include: (1) people with HIV infection; (2) young children and adolescents who have had close contact with a smear-positive TB patient and have a positive tuberculin test; (3) people who have a positive tuberculin test result and are diabetic, long-term hormone users, or long-term immunosuppressant users; and (4) people who have a strong positive tuberculin test result.