Tuberculosis rates in the United States reached an all-time low in 2012, with fewer than 10,000 cases reported even as the global threat of drug-resistant TB rises, but U.S. officials fear progress in beating back the disease could be fleeting.
About a third of the world's population is infected with the bacteria that cause TB, and nearly 4 percent of those newly infected globally are resistant to multiple drugs from the start. That signaled that resistant forms of the disease were being transmitted directly from person to person, the World Health Organization said this week.
Dr. Kenneth Castro, director of the division of TB elimination at the U.S. Centers for Disease Control and Prevention, said the global threat of TB underscores the need for the United States to remain vigilant in fighting the disease.
"As long as TB remains a global problem and we share the air we breathe, we will see opportunities for importation as well as transmission in this country," Castro said in an interview.
Castro, who has led the TB prevention efforts since January of 1993, said the latest numbers show that the United States has successfully beaten back a resurgence in TB rates from 1985 through 1992 that occurred when the U.S. cut back on TB control efforts.
However, he fears that the current progress could tempt lawmakers to cut public health budgets, leaving the United States vulnerable at the very moment when dangerous, drug-resistant strains of the bacteria are spreading globally
"The danger that accompanies this set of news is that there's a risk of renewed complacency," Castro said.
"I can tell you from the perspective of someone who has been in TB for a long time, we've been there and done that before," said Castro. "It took a much larger investment to recover from that and now what we have is 20 years of recovery with the downward trend," he said.
According to the latest report, U.S. TB cases fell 6.1 percent to 9,951 in 2012 or 3.2 cases per 100,000 people, the 20th consecutive year of declines and the lowest rate since national reporting began in 1953.
Most U.S. cases of TB are occurring among foreign-born individuals, in whom infection rates are 12 times higher than among U.S.-born individuals. More than half of foreign-born TB patients in the United States came from just five countries - Mexico, the Philippines, Vietnam, India and China.
Multi drug-resistant TB, or MDR TB, in which the infection resists at least two of the best anti-TB drugs - isoniazid and rifampin - accounted for 1.6 percent of all TB cases in which drug susceptibility testing was completed in 2011, the most recent year for which data are available.
That was up slightly from 1.3 percent reported in 2010. The CDC said there was only one case in the United States of extensively drug-resistant TB, or XDR TB. This rare and dangerous form of TB, which thwarts the most highly effective drugs, was reported in at least 77 countries in 2011, according to the WHO.
Four U.S. states - California, Texas, New York, and Florida - account for roughly half of all TB cases, with 4,967 reported cases.
Treating typical TB is a long process, with patients needing to take a cocktail of antibiotics for six months. Many fail to complete treatment and that has given rise to drug resistance.
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