Tuberculosis: Still Alive and Kicking
While most of us have not heard of an active case of tuberculosis in our own circle, to say it is still a global health problem would be putting it mildly. The National Institute of Allergy and Infectious Disease estimates up to a third of the world's population may be infected with mycobacterium tuberculosis and 10 million new cases are diagnosed each year. Additionally, the Center for Disease Control (CDC) states that there is a 5-10% lifetime risk of progression from inactive to active disease. Certainly this is no goodbye to tuberculosis prevalence.
While the incidence is seen far less, according to percentages, in developed countries like the United States, a 15% increase in occurrence was reported to the CDC during the HIV epidemic of the late 80s and early 90s. The incidence is still significant in the general population due to immigration to the United States from high-incidence countries, illicit drug use, and among those in the rapidly expanding health care field. People who have inactive or latent tuberculosis generally don't feel ill, so the only evidence of infection is a positive screening test, often during an application for employment or as part of school screening.
Tuberculosis enters the body primarily through the lungs. This is the main site of infection although tuberculosis can exist in the bones, lymph nodes, and virtually any place in the body. The disease usually exists in a dormant or latent form. When the infection is progressive, constitutional symptoms such as weight loss, fever, night sweats, and malaise occur. Chronic cough is the most common pulmonary symptom. Blood in the sputum can be a more advanced sign of infection and upon physical examination chronic illness is very apparent.
One problem in eradicating tuberculosis is the inconsistent standards for diagnosing the disease. Cost containment often limits testing to high risk populations and is not offered to those who are likely to refuse treatment. A positive tuberculosis skin test indicates exposure to the disease, but the risk of treatment and side effects often exceeds the potential benefit in older individuals and those who have not converted from negative to positive in a recent timeframe. Tuberculosis is verified by isolating the bacillus and a chest x-ray, sputum, and a culture to confirm the diagnosis.
Once discovered, tuberculosis should be treated immediately. Isoniazid (INH) is the primary drug of choice, and as the disease is a tough one to eradicate it often requires between 6 and 9 months of continuous treatment. Many other medications have been developed but unfortunately strains of drug resistant disease have emerged. The toughest cases affect those whose systems are immunosuppressed (individuals with a disease like HIV infection) and the elderly, where reactivation occurs after many years of dormancy and the immune system isn't as active as it is in the younger ages fighting the disease. Treatment failure does occur frequently since most affected do not maintain the medication schedule for the lengthy period necessary to completely inactivate the disease.
Authored by Dr. Bob Goldstone, M.D.
The information contained on this page is not intended to provide medical advice, which should be obtained directly from your physician.