After an unprecedented increase in reported cases of tuberculosis in the United States that began in 1986, the disease has been brought under control. In 1999, the number of reported cases of tuberculosis declined to an all-time low of 17,528, and the country recommitted itself to the goal of tuberculosis elimination that was first announced in 1989.¹ Although new tools, such as an improved, effective vaccine, will be needed to eliminate tuberculosis, much can be accomplished with the improved use of current technologies.

Among the available control measures, treatment of persons with active tuberculosis is of paramount importance, especially to decrease morbidity and mortality and prevent secondary transmission to others. However, in the United States, the majority of active cases of tuberculosis occur among those with latent tuberculosis infection acquired in the past. Thus, the treatment of persons with latent tuberculosis infection who are at high risk for developing active disease is also a critical component of the elimination strategy.

In recognition of the importance of latent disease, the American Thoracic Society (ATS) and the Centers for Disease Control and Prevention (CDC) have recently issued a new statement titled, “Targeted Tuberculin Testing and Treatment of Latent Tuberculosis Infection.”² The salient points of these new recommendations are summarized in the review of tuberculosis diagnosis, treatment and prevention by Jerant and colleagues,³ published in this issue.

Hence, the diagnosis and treatment of latent tuberculosis infection should be of major concern to family physicians, and primary care physicians will play a significant role in the elimination of tuberculosis in the United States. New cases of tuberculosis largely occur among persons in two risk groups: those who have recently been infected and those with medical conditions that facilitate the progression of latent tuberculosis infection to active disease. It is persons in these groups who are the focus of the new guidelines for management of latent tuberculosis infection. The ATS and the CDC are calling for increased testing for latent tuberculosis infection, but they are focusing on persons in these risk groups and discouraging testing in those who are at lower risk.

Although treatment of persons with active tuberculosis will often remain the domain of public health departments and medical sub-specialists (pulmonologists and infectious disease subspecialists), targeted testing for latent infection and treatment of high-risk infected persons will increasingly become a function of private practice, community health centers and managed care plans. Several categories of patients are of particular relevance: persons who have recently immigrated to the United States from tuberculosis-endemic countries and those with high-risk medical conditions.

Forty percent of new cases of tuberculosis in the United States are in persons born in other countries who have reactivation of latent infections.⁴ These persons and those with the medical conditions listed in Table 1 of the review article by Jerant³ should be tested for latent infection. In addition, family physicians may see a large number of persons whose occupation places them at risk of tuberculosis and who are found to have latent tuberculosis infection.

A complete understanding of which persons should be treated and with what drug or drug regimen is essential, and the new ATS/CDC recommendations also highlight new guidelines for the treatment of latent tuberculosis infection. After repeated analysis of data from clinical trials of isoniazid for the treatment of latent infection, the statement concludes that nine months of treatment with isoniazid (INH) provides optimal benefit and is preferred for all categories of patients.⁵ Although considerable benefit is also provided by six months of isoniazid treatment, the nine-month regimen should be given to children, patients with human immunodeficiency virus (HIV) infection and those with radiographic evidence of previously untreated tuberculosis.

Based on recent data from clinical trials in HIV-infected persons, a new two-month regimen of rifampin (Rifadin) and pyrazinamide, both commonly used drugs for treating patients with active tuberculosis, appears to provide protection equivalent to that of isoniazid.⁶ This regimen is recommended for use in adults with or without HIV infection. The advantages of this much shorter treatment regimen must be balanced against the costs and higher incidence of minor side effects, but it may be especially useful in cases in which the longer course of isoniazid treatment has not proved feasible. Finally, treatment with rifampin alone for four months is also an acceptable regimen.

The guidelines on baseline testing and treatment monitoring have also been revised to emphasize clinical rather than laboratory monitoring.⁷ Clinical monitoring involves education of the patient about signs and symptoms of tuberculosis and drug toxicity, as well as careful questioning and repeated education at monthly intervals. Laboratory monitoring is indicated for HIV-infected persons, pregnant and postpartum women and those with a history of or risk factors for hepatic disease.

Changes in the epidemiology of tuberculosis and the new guidelines have set the stage for new opportunities in tuberculosis control. Risk assessment, targeted testing and implementation of new treatment regimens by primary care physicians will contribute significantly to the elimination of tuberculosis in the United States.