Many South Asian immigrants from countries where tuberculosis (TB) is common do not get tested even though they are at high risk for developing the disease, according to a recent study by Rutgers University and St. Peter’s University Hospital.

Scanning electron micrograph of Mycobacterium tuberculosis bacteria, which cause TB. Credit: NIAID

Tuberculosis, which mainly affects the lungs, kills more people worldwide—about 1.6 million—than any other single infectious illness.

The study appears in the Journal of Community Health.

The researchers found that many South Asian immigrants who regularly visit their birth countries may have latent TB and, given the lack of symptoms, often do not get tested. People with latent TB are not infectious and cannot spread the disease.

“Our work shows more needs to be done to screen and treat asymptomatic latent TB infections in our community, which is a new focus of the Centers for Disease Control and Prevention [CDC] as well,” said study senior author Sabah Kalyoussef, a clinical assistant professor at Rutgers Robert Wood Johnson Medical School and St. Peter’s University Hospital.

Approximately 1.7 billion people worldwide, including 13.6 million in the United States, have latent TB. Although developed countries such as the United States have a low incidence of TB, cases are often imported from recent travelers or immigrants.

According to the CDC approximately 70 percent of TB cases in the United States occur in foreign-born individuals, especially in Asian populations. New Jersey, which has the highest percentage of Asian-Indians in the United States, is one of the top 10 states with the highest incidence of TB.

The researchers surveyed 463 adults who were born in Bangladesh, Bhutan, India, Nepal, Pakistan, the Maldives, Afghanistan or Sri Lanka over four months to better understand their attitudes and health behaviors toward TB. Of these, 387 were born in a high TB burden country such as Bangladesh, India or Pakistan and many regularly return to these countries.

The results showed that only 54 percent of all participants reported being tested for TB despite most being highly educated, having high household income and health insurance, believing TB was a serious disease and placing high importance on being tested.

The researchers said possible reasons for not being tested include cultural biases, stigma associated with TB, attitudes on the benefits of testing and treatment or physicians not appropriately testing their high-risk patients or not asking about their patients’ travel history.

“An important step toward elimination of tuberculosis in the United States is identifying those with latent infection and treating those at high-risk for reactivation,” said Kalyoussef. “This study shows that more work needs to be done in the community and at the physician level about the risks of latent TB infection in the high-risk populations.”

The researchers plan to use the study results to try to persuade at-risk South Asian immigrants to be screened and treated for latent TB infection.