A study published on the July 22 issue of the Journal of the American Medical Association called for more aggressive action against tuberculosis, after it had discovered an increase in the number of foreigners in the US infected with TB.

Although TB cases in the US dropped 45 percent between 1996 and 2006 (from more than 25,000 to less than 14,000), according to the US Centers for Disease Control and Prevention’s statistics, there was a five percent increase in TB cases among immigrant populations living in the US during the same period, Dr. Kevin P. Cain head of the CDC’s Division of Tuberculosis Elimination and lead author of the study said.

According to the study, 57 percent of all reported TB cases in the US are among foreign-born individuals. Of those, more than half were among immigrants from sub-Saharan Africa and Southeast Asia, even though they make up less than a quarter of the foreign-born contingent.

For the study, Dr. Cain studied data from the US National TB Surveillance System, which registered 46,970 cases among foreign-born persons in the US between 2001 through 2006. Of those, 12,928 (28 percent) were among those who had entered the country within two years.

Moreover, TB cases were four times higher among foreign-born immigrants than among US-born people even for those who had been living in the US for more than 20 years, the study found.

Rates of TB varied substantially by country and region of origin. For example, individuals born in countries of sub-Saharan Africa had annual case rates of greater than 250 per 100,000 persons during the first two years after entering the US. Annual rates were greater than 100 per 100,000 persons for individuals born in Central America, Eastern Europe, the Pacific Islands and South, East and central Asia. By contrast, people born in Western Europe, Canada, Australia, and New Zealand presented lower risk of TB of less than 10 per 100,000.

Dr. Cain said it is impossible to test the 37 million foreign-born individuals currently living in the US. However, 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.

Dr. Cain said that screening immigrants and refugees from the Philippines and Vietnam would have detected almost half the average 250 TB cases brought into the US annually between 2001 and 2006.

In order to prevent TB cases, Dr. Cain suggested that immigrants should receive overseas diagnosis and treatment prior to immigration, especially those coming from the countries with the highest rate of infection. Another way to curb TB rates would be to find and treat latent TB infections. In these cases, germs are present but the body is able to fight off symptoms. The infection becomes active and able to spread once the immune system begins to weaken as we get old or in case of a serious disease.

However, he added that “as long as TB is out of control globally, as it is, this will be a problem in the US. If you breathe, you’re at risk for TB. This can affect anyone.”