Tuberculosis is a highly contagious respiratory disease, typically spread by coughing. For this reason, health care workers, child care providers, teachers and others who work closely with the public are routinely screened for TB with a PPD skin test. Tests are read 48 to 72 hours after the injection, and a positive test will appear as a raised red bump, or welt (see picture). If positive, an antibody blood test if typically run to confirm the PPD findings and, if positive, a chest xray is performed, looking for active infection.
Active TB is chest xray proven infection, which is highly contagious. Patients with this disease typically have symptoms of cough, shortness of breath, fever and night sweats. Combination antibiotics are prescribed, and care is generally supervised by an infectious disease specialist. Latent TB is exposure to TB as demonstrated by positive skin testing and/or antibody blood test, but with a negative chest xray. These patients are not infectious, and may work with the general public. However, they are at risk of later developing active TB, especially within the first two years of exposure. For this reason, patients under the age of 35 are frequently offered a course of medication (typically taken for nine months) to decrease the risk of developing active TB in the future…..Richard R Samuel, MD Family Practice and Urgent Care Hayden, ID USA