In 1995, more people in the world died of tuberculosis than in any other year in history.1 The incidence of tuberculosis is increasing, even in the United States. From 1953, when national statistics on tuberculosis were first kept, until 1981, a 5 percent annual decrease in the number of cases of tuberculosis was recorded, and from 1981 until 1985, a 6 to 7 percent annual decrease was reported. However, from 1985 until 1993, there was an almost 10 percent increase in the number of cases of tuberculosis. From 1993 until 1994, a small decrease in the number of cases occurred, perhaps because of enhanced interest in the problem.2 A level of neglect regarding the seriousness of tuberculosis through the 1970s and 1980s worldwide has resulted in the spread of tuberculosis that we now see. Medical schools under-emphasized the public health aspects of tuberculosis control, ministries of health minimized tuberculosis control, and it was disregarded by most funding agencies. The result is that tuberculosis has a higher mortality rate in adults than any other infectious disease worldwide. The tuberculosis epidemic has become a global emergency, and it will not go away on its own. In 1995, for each person who died of the Ebola virus, 12,000 people died of tuberculosis.1 If tuberculosis were a new disease like Ebola, the world would spare little expense to fight it, but tuberculosis has been around for centuries and has become an old, familiar enemy that we have learned to overlook. It is easy to understand why the tuberculosis epidemic is getting worse: For each person who has tuberculosis and is improperly treated, 10 to 15 other people per year may be infected.
The epidemiology of tuberculosis is changing in the United States and around the world. As the number of cases increases in developing nations, the threat to people in the United States increases because of air travel and immigration. The most significant change in the epidemiology has been the number of cases diagnosed in people infected with human immunodeficiency virus (HIV) infection. Another very worrisome change has been the recent outbreaks of multidrug-resistant tuberculosis.
In the United States, more than two thirds of cases of tuberculosis occur in non-white racial and ethnic groups. More than one fourth of all cases in the United States occur in foreign-born individuals, and about one third of these people have been residing in the United States less than one year.3 It is of interest that nearly one third of the cases of tuberculosis in the United States occur in persons in the middle- and upper-income groups, despite the popular notion that tuberculosis is a problem of only the poor.
Infectious diseases in general are thriving as the world's population becomes more mobile. Global trade has multiplied sixfold since 1960, and people from all parts of the world fly from country to country on business, on vacation or to attend school. The United States is now receiving over 20 million foreign visitors annually, and U.S. citizens are taking nearly 60 million trips annually to foreign countries. The public health implications of this increased travel have not been fully appreciated. This increased mobility can place your patients at risk of exposure to tuberculosis and other infectious diseases through contact while flying, contact while in a foreign country or contact with foreign visitors to this country. This increased mobility also means that every country is vulnerable to the inferior tuberculosis treatment practices of other countries.
Worldwide, more HIV-infected people die from tuberculosis than from any other cause; tuberculosis is the cause of death in about one third of those who die from acquired immunodeficiency syndrome. Those people who are immunosuppressed because of HIV or because of other causes are 30 times more likely than nonimmunosuppressed individuals to acquire tuberculosis when exposed to it and will develop the disease more rapidly. Yet they can be cured of tuberculosis if diagnosed in time and treated appropriately. The seriousness of this combination of immunosuppression and tuberculosis has led the Advisory Committee for the Elimination of Tuberculosis of the Centers for Disease Control and Prevention to recommend that all patients in whom tuberculosis has been diagnosed be offered counseling and HIV testing, and that all HIV-infected individuals, with or without AIDS, should be given a tuberculin skin test.4
We face a very serious threat that tuberculosis will become impossible to cure in the future. The increase in the number of cases of multidrug-resistant tuberculosis is seen worldwide, and although the extent of this problem is not known, it is estimated that 50 million people are infected with a drug-resistant form of tuberculosis. In this country, several outbreaks have been investigated, and most of the exposed people who developed multidrug-resistant tuberculosis were known to be infected with HIV. The case-fatality rate among these individuals was extraordinarily high—72 to 89 percent.5,6 In developing countries, people with multidrug-resistant tuberculosis usually die because effective treatment is often impossible in poor settings, but even in more affluent countries, up to 50 percent of people with multidrug-resistant tuberculosis may die because of the expense and difficulty of proper treatment. Multidrug-resistant tuberculosis is created by prescribing the wrong drugs or the wrong combination of drugs in the treatment of tuberculosis. It can also occur if the right drugs are prescribed but are not taken consistently or for a full course of treatment. Multidrug-resistant tuberculosis has the potential to return humanity to an era when the diagnosis of tuberculosis was a virtual death sentence.
We know from the past that tuberculosis is controllable if appropriate measures are taken and sufficient interest in doing so exists. These measures include identification of cases, proper treatment regimens, contact identification and follow-up, and proper preventive treatment of those exposed to the disease. Most people with tuberculosis are identified either because they seek medical treatment for their symptoms or because they are being treated for other conditions and are found to have concurrent tuberculosis infection. Family physicians are among the most important identifiers of people with tuberculosis, but because of the nonspecific manifestations of the disease, a high index of suspicion must be maintained, especially in those individuals who are at greatest risk. Evaluation of the contacts of people with infectious tuberculosis is one of the most productive methods of identifying persons with infection and disease. We must ensure that local authorities are doing this effectively. Proper treatment is critical to containing this epidemic, and the key is that patients not only be treated but that they also be cured. Patients frequently forget to take their medicines or stop treatment when they begin to feel better. The treatment strategy that has proved most effective is called directly observed treatment course (DOTS). This strategy uses a combination of four drugs to kill the tuberculosis bacteria within six to eight months, and it virtually guarantees a cure because health workers actually watch patients swallow their medicines and evaluate their patients' progress. Widespread use of DOTS would soon reverse the course of this worldwide tuberculosis epidemic. Family physicians must continue to take an active role in helping curb this epidemic and must remain knowledgeable about tuberculosis as the epidemiology evolves and treatment regimens change.