Widespread efforts to control tuberculosis in California have largely failed to cut rates of dangerous drug-resistant forms of the disease.
The new report shows that tuberculosis cases have steadily declined since 1994 in the state. However, the proportion of patients with tuberculosis resistant to multiple antibiotics held steady at around 1.5 percent of all cases. More needs to be done to identify and control the illness both in the U.S. and abroad in order to cut rates of the disease, researchers say.
"Basically it's a flat line. It's not decreasing," Reuben M. Granich, MD, a researcher for the study, says of multidrug-resistant (MDR) tuberculosis rates.
"We really can't do this in isolation. We have to do this in California, the United States, and overseas," says Granich, a researcher with the CDC division of tuberculosis elimination.
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Tuberculosis is a bacterial infection of the lungs. Some people can carry the bacteria in their bodies but don't have any symptoms -- and they aren't contagious. People with active tuberculosis typically have a cough with thick and sometimes bloody mucus for more than two weeks.
Tuberculosis is normally treated with six to nine months of multiple antibiotics. But if patients take medication improperly or don't complete treatment, some TB bacteria can be left in the body. When those heartier bacteria multiply, an entire new generation of drug-resistant bacteria can arise.
Public health departments and doctors try to combat the problem by closely observing patients taking medication each day, in an effort to ensure complete treatment. The treatment involves detailed testing and even interviews with patients' personal contacts, all of which can cost hundreds of thousands of dollars.
But evidence suggests that in California, resistant disease is still a problem, Granich says.
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Researchers looked at nearly 29,000 tuberculosis cases reported in California between 1994 and 2003. The state has the most tuberculosis cases of any state, with approximately one-third of all the nation's patients. New York and Texas round out the top three states for the most tuberculosis cases.
Of those cases, 407 were found to be resistant to isoniazid and rifampin, two of the most common antibiotics used to treat tuberculosis. More than one in five of the patients had resistance to all four drugs used to treat tuberculosis.
Patients with drug-resistant tuberculosis are four times more likely to die than patients with standard tuberculosis. Forty-nine of the California patients, or 14 percent, died from their drug-resistant infections, according to the study, published in the Tuesday issue of The Journal of the American Medical Association.
A total of 233 Americans died in 2003 from all forms of tuberculosis. That pales in comparison to death rates in developing nations, where tuberculosis often infects up to one-third of the population, according to the CDC.
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Tuberculosis Not Just in Cities
Epidemiologists have long observed that tuberculosis tends to concentrate in urban centers. But researchers were alarmed by findings showing reports of multidrug-resistant tuberculosis in more than half of California's health jurisdictions, including several rural counties.
"Multidrug-resistant TB has spread across the state," Granich says.
Researchers call for stronger efforts aimed at identifying and treating tuberculosis overseas, noting that the majority of infected persons in the California study were from foreign countries. They also note that one-third of multidrug-resistant tuberculosis patients in California did not complete their treatment and that officials must step up efforts to improve complete treatment of the disease.
Catherine D. DeAngelis, MD, editor of JAMA, told reporters that relatively low domestic tuberculosis rates have convinced much of the public that the disease is no longer a threat in the U.S. But worldwide tuberculosis infection rates are 33 times higher than those for HIV.
"Don't get too comfortable. It is a global problem," she says.
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SOURCES:The Journal of the American Medical Association, June 8, 2005; pp 2732-39. Reuben M. Granich, MD, division of tuberculosis elimination, CDC. Catherine D. DeAngelis, MD, editor, JAMA.