According to a study published this week in the Journal of the American Medical Association, there's been an increase in the number of foreigners in the United States who are infected with tuberculosis.  The authors are proposing a strategy to control disease among high-risk groups.   VOA's Jessica Berman reports.

According to the U.S. Centers for Disease Control and Prevention in Atlanta, Georgia, the number of tuberculosis cases in the United States dropped  45 percent between 1996 and 2006.

Officials say the lion's share of the decrease - 66 percent - occurred among U.S.-born individuals.   But  they say there was a five percent increase in TB cases among immigrant populations living in the United States during the same period.

Today, the CDC says, 57 percent of all reported TB cases in America are among foreign-born individuals.  

U.S. health officials say their main concern is the spread of latent TB  which infected individuals bring into the United States from their countries of origin without being detected.    

Kevin Cain is head of the CDC's Division of Tuberculosis Elimination.  He says officials want to step up efforts to detect individuals with latent TB who enter the country.

Cain led a study of 49,970 cases reported to the CDC from 2001 through 2006.  

Investigators looked at the émigrés country of origin and the age at the time of entry into the United States.

"What we found in the study is that for example over half of all cases of TB among foreign-born persons occur among just 20 percent of the overall foreign-born population," said Kevin Cain. "That includes mainly persons who are born in Southeast Asia, sub-Saharan Africa and South Asia as well."

Cain says it is impossible to test the 37 million foreign-born individuals currently living in America.  But the findings would help officials make better use of TB control resources.

"We believe that this is helpful because, while it might not be possible to test and treat all foreign-persons for latent TB, if programs can try to focus on the highest risk groups and can reach out to the populations that need this testing and treatment the most, then they'll have a greater chance of preventing as many cases as possible for the number of tests that they are able to do," he said.

Investigators also propose enhancing TB testing of visa applicants at the country of origin to include not only a skin test and chest X-ray, but a saliva test to look for the bacterium in culture.

But Cain says the ultimate safeguard against tuberculosis is global elimination of the disease.