TB Update: Is OSHA Standard Needed?
TB wanes in U.S., but CDC warns of complacency
Incoming: Global epidemic poses next major threat
The four-year decline in tuberculosis in the United States masks several areas of ongoing concern for a disease that has historically rebounded whenever it has met with complacency, warns the Centers for Disease Control and Prevention.
Declining TB has traditionally been followed by a corresponding reduction in TB funding and control efforts, leading to subsequent rise in cases that creates the so-called "U-shaped curve of concern."
"As the [TB] rates drop it is more likely that the program used to combat the disease will be eliminated rather than the disease itself," says Patti Simone, MD, medical epidemiologist in the CDC TB elimination branch. "But TB is not going down in every community. There are still places with stable or increasing rates."
According to CDC data, there are currently an estimated 10 million to 15 million Americans infected with TB, and about 10% will develop active disease at some point in their lives. In 1996, there were 21,327 cases of active TB reported in the United States, a decline of nearly 7% from the 22,860 cases in 1995. The latest figures represent the fourth consecutive annual decline in U.S. TB cases, suggesting that the nation is recovering from the resurgence of TB that occurred in the mid-1980s and the goal of TB elimination may again be possible for the nation, the CDC reports.
While TB cases declined nationally, however, TB cases continued to increase in some areas. Twenty of the 50 states and the District of Columbia reported either no change or an increase in TB cases. (See charts, pp. 122-123.) In addition, 1996 was marked by sporadic outbreaks of drug-resistant TB, including wider dissemination of a multidrug-resistant strain that originally emerged in New York City.
2 billion people worldwide still have TB
"We also have an increase in TB in foreign-born persons, and that can’t be addressed by doing TB control and prevention efforts here in the U.S.," Simone says. "It takes a more complex approach. The global TB picture is really increasing, and we don’t live in an isolated environment."
Despite the decline in the U.S., some two billion people about a third of the world’s population are infected with TB, the CDC reports. Each year there are eight million new cases of TB and three million TB deaths. An increasing proportion of cases in the United States occurs among people born in areas where TB is common, such as Asia, Africa, and Latin America. Cases among individuals born outside the United States increased from 4,925 cases (22% of national total) in 1986 to 7,739 cases (37% of national total) in 1996.
"How we address TB prevention and control in the foreign-born is a big challenge," Simone says. "There is a huge number of people, and we can’t get all of them tested and give them preventive therapy. There are not near the resources for that. So we concentrate a lot on case-finding. We very carefully follow legal immigrants who are referred in as having an abnormal X-ray."
TB was once the leading cause of death in the United States, but the discovery of effective TB drugs in the 1940s put the nation on a path to TB elimination until the mid-1980s. With prevention and control funds redirected to other areas, TB began a dramatic resurgence that resulted in a 20% increase in cases between 1985 and 1992. Likewise, drug-resistant strains emerged at a time when communities lacked the resources to follow through with patients to ensure compliance with treatment. Compounding the problem, clinical laboratories did not have the diagnostics needed to rapidly identify strains before incorrect treatment was begun, leading to emergence of resistant strains even more difficult to treat. As funds were restored to programs particularly directly observed therapy programs to ensure patients’ completion of drug regimens the number of cases began its current decline, the CDC emphasizes.
"The fact that TB particularly multidrug-resistant TB is being controlled is because of the large infusion of federal and state funds and the improvements in both hospital and community TB control programs," says William Jarvis, MD, chief of the investigation and prevention branch in the CDC hospital infections program. "Those things would not have happened without increased funding. We have to guard against becoming complacent, dropping our funding and our guard, and having this take off again."
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