Half will become ill within the first 2 years of becoming infected, while the other half will develop active disease at some point later in their lives. Most cases of active disease are the result of reactivation of an endogenous infection. This occurs when the person s immune system becomes compromised in some way. Persons infected with HIV are at a much higher risk of progressing to active disease than those whose immune systems are intact. General systemic symptoms of active tuberculosis include fever, fatigue, loss of appetite, and weight loss.
Specific symptoms depend upon the site of disease, which can occur in almost any organ system.
Tuberculosis must be treated with several drugs, typically isoniazid, rifampin, pyrazinamide, and ethambutol, for a long period of time. Treatment periods usually range from 6 to 9 months or longer, depending on the site of the disease, age, response to therapy, and drug resistance. Latent TB infection is usually treated with isoniazid alone for a recommended period of 9 months regardless of age or HIV status. The year 1999 marked the seventh consecutive year in the decline in the numbers of new TB cases. There were 17,531 cases reported nationwide for a rate of 6.4 cases per 100,000 population.