Active Tuberculosis
Class 3 includes anyone with active TB based on the presence of symptoms or positive laboratory testing. Typical symptoms include a persistent cough that may produce blood or mucus, fever, chills, night sweats, pain in the chest, loss of appetite, weight loss and weakness. A diagnosis of active TB can be confirmed via a number of lab tests, the most important of which is identifying the presence of Mycobacterium tuberculosis -- the bacteria that causes TB -- in the body. The most common way to diagnose active pulmonary TB is by finding the bacteria in a sample of sputum.
Inactive or Suspected Tuberculosis
Class 4 TB identifies people who had active TB in the past but no longer show any evidence of active disease. Their skin tests are positive and chest x-rays may be abnormal, but they have no symptoms and their lab tests are negative. Class 5 includes those individuals who are suspected of having TB but are still waiting for test results to confirm whether they have the disease. Some people in class 5 may already be receiving treatment while they wait for the final test results. Once all test results are completed, the individual will be moved to the most appropriate class.