The number of tuberculosis cases in the United States rose last year for the first time in nearly a quarter-century, the Centers for Disease Control and Prevention reported Thursday.
Twenty-nine states and the District of Columbia each had more cases in 2015 than 2014, raising questions -- but no definitive answers -- about a possible resurgence of one of the world's deadliest diseases.
The overall increase was relatively small: 157 more cases, bringing the 2015 total to 9,563. Two-thirds of the total were among people born abroad, with Asians accounting for the most cases (3,007) and the highest rate (28.2 cases per 100,000 persons). By comparison, there were only .5 cases per 100,000 whites last year.
"After two decades of declining incidence, progress toward TB elimination in the United States appears to have stalled," the CDC report said. The causes are unclear, it said, and the data need further evaluation if the reasons behind the trend are to be identified.
One contributing factor is likely to be reduced or stagnant funding for prevention efforts nationwide. The disease can be difficult to manage and treat, even more so if substance abuse, incarceration or homelessness are involved. Advocates say that people with TB often have other diseases, such as diabetes, that also complicate treatment.
The authors noted that reports of TB cases among native-born children are further corroboration of the disease's continued spread in the United States; diagnosis in a young child represents "a sentinel event" signaling recent infection.
Tuberculosis is a serious airborne bacterial disease that primarily attacks the lungs. The active form is contagious, while people latently infected don't show symptoms and are not contagious. About 11 million Americas are believed to be in that latter category, according to the CDC's last estimate in 2000.
The disease is treatable with antibiotics, but the course can be long and complicated. Certain forms of the bacterium that causes TB are becoming impervious to the drugs designed to kill them, leading to the development of multidrug-resistant strains of infection.
More than half of cases reported in 2015 were clustered in four states — California, Florida, New York and Texas — which have one-third of the U.S. population.
"There have been devastating [budget] cuts in some states, so they have only been able to react to cases," said Donna Wegener, executive director of the National TB Controllers Association, which represents all public tuberculosis-control programs at the state and local levels. "We've reached the limits of what we can do without a robust prevention program, currently not funded."
Texas saw 1,334 cases in 2015, which was 5 percent more than the previous year.
"We are clearly going in the wrong direction," said Jeff Starke, a pediatrics professor at Baylor College of Medicine who runs the children's TB clinic at Texas Children's Hospital in Houston.
Although new diagnostic tools and treatments are in development, the bottom line for clinicians means "using drugs that are 50 years old and diagnostics that are 100 years old," he said.
South Carolina experienced a 32 percent increase year over year, with 104 cases in 2015. Melissa Overman, a regional medical director at the state's health and environmental control department, said she is seeing sicker patients who don't always finish their therapy for latent TB. The spike in cases is prompting officials to encourage clinicians to "think more proactively of tuberculosis as a possible diagnosis and make a fast referral to us to do a rule-out," she said.
Health officials said progress toward eliminating TB in the United States will require a redoubling of domestic and global efforts — especially in China, India, Mexico the Phillipines and Vietnam, the countries responsible for more than half of the foreign-born tuberculosis patients in the United States, the report shows.
In a related report, the CDC also called for increased awareness of the potential for active TB among foreign-born temporary workers. TB screening is required for persons seeking permanent residence in the United States, but it is not routinely required for people coming on temporary visas for school or work. Those numbers are not included in official case counts.
The separate report described three foreign-born workers who had infectious tuberculosis while working at tourist destinations in Arizona and Michigan between 2012 to 2014. Health authorities conducted extensive screening of their contacts, and no additional active TB cases were identified.
In one case, a 49-year-old man from the Philippines arrived in April 2012 on a temporary visa to work as a butcher at a resort restaurant on Mackinac Island in Michigan. The island, with a population of about 500, had not reported a TB case since 1995. When the resort closed in October, he relocated to California and was admitted to the hospital in May 2013 with cough, weight loss, chills and fever. After he was diagnosed with TB, authorities tried to track down 68 employees who came in contact with him. Thirty-five had left the state. Of the others, 13 were considered to have latent TB infection, the report said.
Though the incidence of TB has been declining globally, there were 9 million new tuberculosis cases and nearly 1.5 million fatalities in 2013, according to the World Health Organization.