结核传播及发病机理感染控制培训班.pptVIP

The slide is self-explanatory. The Objectives of the Unit are critically important for the continuation of the course. After initial description of mechanisms of TB transmission, principles of TB Infection Control (IC) and factors influencing the risk of TB transmission, participants will be ask to discuss how to minimize this factors to prevent transmission in In-patient wards and Out-patient clinics. Finally, the package for infection prevention and control in health care and congregate settings is introduced. There are three mechanisms leading to TB disease. The first one is represented by progression of primary infection to disease. The second mechanism is represented by endogenous reactivation of the previously dormant bacilli, often due to a decreased immunity The third mechanism is exogenous re-infection (when more bacilli are inhaled from a source case) This slide shows the difference between TB infection and TB disease. One third of the global population is infected with M. tuberculosis. In TB infection, the TB bacilli are present in the body but they are not replicating; the person’s immune system keeps them in the dormant (latent) phase. The individual has no signs or symptoms of TB and feels well. Chest radiograph (chest x-ray, CXR) is normal, and bacteriological examinations such as smear and culture are negative. People with latent TB infection usually have a positive tuberculin skin testing using purified protein derivative (PPD) People with latent TB infection cannot transmit TB to others; they are not infectious. When TB disease develops, the situation is different, as described in the right column of the table. The TB bacilli are replicating, the patient usually feels sick. If the site of TB is the lungs, the patient will have an abnormal CXR and often positive sputum smears or cultures The tuberculin skin test is usually positive. Patients with TB of the lungs are likely to spread TB to others. Cases of TB di