CHICAGO (Reuters) - Thousands of immigrants arrive in the United States sick with tuberculosis or at risk for the contagious and deadly disease, which points to the need to improve efforts to find them, researchers said on Tuesday.
The Centers for Disease Control and Prevention in Atlanta found the highest rates of tuberculosis among immigrants and refugees born in Sub-Saharan African countries including Somalia and Ethiopia; from Southeast Asia including Cambodia and Vietnam; and from parts of Latin America such as Peru.
The researchers suggested improving screening efforts among emigrants coming from high-risk countries -- who accounted for 4,035 TB cases in the United States in 2006 -- before they depart. The alternative is to test and treat them soon after they arrive.
“Our goal should be address this serious health concern in the communities that need it the most,” said Dr. Kevin Cain, who conducted the study with colleagues at the CDC. “As long as TB is out of control globally it will be a problem for the United States.”
Progress made against the disease cut the number of U.S. cases in half between 1993 and 2006. But U.S. cases among foreign-born persons rose 5 percent during the period and they accounted for 57 percent of all U.S. cases in 2006.
Twenty-two percent of the 37 million foreign-born people in the United States came from sub-Saharan Africa and Southeast Asia, but they account for more than half of tuberculosis cases among those born outside the country, according to the study published in the Journal of the American Medical Association.
Most TB cases develop within the first two years of entry into the country, but the disease can show up decades later.
The scale of the problem is enormous, Cain said.
Tuberculosis is endemic globally with 9 million people becoming ill each year and 2 million dying from the disease. One out of three people globally have been exposed to the microbes that cause the disease, though 95 percent of them have strong enough immune systems to hold the infection at bay.
The disease usually attacks the lungs, resulting in fevers and coughing fits with blood-tinged sputum that can infect many more. A skin or blood test can detect latent infections.
Most troublesome are cases that are resistant to commonly used antibacterial drug treatments. Around one out of five TB cases among U.S. immigrants from Vietnam, Peru, the Philippines and China were found to be drug-resistant, the study found.
HIV-infected patients with weakened immune systems are susceptible to TB, and they and their caregivers merit close monitoring, a separate study in the journal concluded.
The imperfect overseas screening process conducted by the CDC to detect active TB cases involves a chest X-ray, with any abnormality prompting an examination of sputum under a microscope to confirm the disease. A new U.S. rule put in place last year calls for culturing the sputum in suspected TB cases, which can take as long as eight weeks.
Cain said one gap in the process that may need closing is the roughly 30 percent of foreign-born people in the United States -- students, temporary workers, tourists and, of course, undocumented immigrants -- who are not screened.
“Addressing the burden is going to require a multifaceted approach: one is enhancing overseas screening and treatment,” Cain said. The other is to screen rapidly and treat those already here, focusing on people from high-risk countries.
Cain said screening immigrants who otherwise feel healthy requires delicacy and sensitivity to cultural differences.
Treatment requires daily drug dosages over nine months, though an experimental once-a-week 12-week regimen may work.
Ultimately, the goal will be to develop a TB vaccine.
For now, “when treatment targets are met, the burden of TB in a country has declined. It’s a relatively simple strategy,” Cain said.
Editing by Michael Conlon and Cynthia Osterman