Overseas TB Testing, Treatment of US Immigrants Reduces Spread

Lorraine L. Janeczko, MPH

February 24, 2022

Potential immigrants to the United States from countries with high rates of tuberculosis tend to follow through with TB tests and treatment before they travel, and their compliance helps control TB spread, according to a study published online February 16 in Emerging Infectious Diseases.

Dr Christina Phares

"In our study of US-bound immigrants in Vietnam during their required overseas medical examination prior to migration to the United States, we identified a high proportion of US-bound immigrants with latent TB infection (LTBI) and offered them preventive TB treatment," co-author Christina R. Phares, PhD, of the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, told Medscape Medical News.

"Overall, 88% of those who started treatment completed their treatment," she said in an email. "This is a higher treatment completion rate than has been found in many post-arrival strategies in the US."

"This study demonstrated that providing LTBI testing and treatment during the overseas medical examination is feasible, yields high initiation and completion rates, and should be considered as a viable strategy to address LTBI in US-bound migrants," lead author Amera Khan, DrPH, of the Stop TB Partnership in Geneva, Switzerland, said in an email.

Dr Amera Khan

The research team began the 1-year Preventing Tuberculosis Overseas Pilot Study (PTOPS) in Vietnam in 2018 among applicants for US immigrant visas. Study participants were 12 years of age or older and were undergoing required medical examinations, which included the interferon-gamma release assay (IGRA) tuberculosis blood test.

Eligible IGRA-positive participants who planned to complete their LTBI treatment before traveling to the US were offered free 3HP (12 weekly doses of isoniazid and rifapentine). Of 5311 people recruited into the study, 2438 (46%) enrolled; 2276 had an IGRA processed; and 484 (21%) tested positive. Of the 452 participants eligible for 3HP, 304 (67%) began, and 268 (88%) completed, their treatment.

Pre-immigration Strategies Needed

Worldwide, TB is now the second-leading cause of death by infectious disease, behind COVID-19, Khan said. The US has seen a slow, steady decline in incidence with an increasing proportion of TB found in people born outside the country.

"Approximately 70% of US TB cases occur in persons born outside the US, with the vast majority due to reactivation of latent TB infection acquired prior to their travel to the US," she said. "To progress towards elimination TB in the US, we need innovative strategies to address the high burden of LTBI among immigrants."

Jonathan E. Golub, PhD, MPH, an infectious diseases specialist and a professor of medicine, epidemiology, and international health at Johns Hopkins University School of Medicine in Baltimore, Maryland, was not involved in the study but welcomed its results. "This study clearly shows that a pre-departure screening and treatment strategy for LTBI can be successfully implemented," he told Medscape Medical News by email. "While the study highlights areas of the LTBI care cascade that need improvement, the message is clear that pre-departure screening and treatment has the potential to significantly impact TB rates among non-US-born persons in the US."

Dr Jonathan Golub

Golub went on to explain that new technologies for LTBI screening have been underutilized. "New, shorter LTBI treatment regimens provide more feasible choices for both providers and people applying for immigration visas. Combining IGRA with 3HP creates an efficient and effective strategy. This strategy had not been tested prior to the study and the results are exciting."

Golub highlighted one important aspect of the study: that many participants started treatment in Vietnam and completed it in the US. "This shows that such a protocol provides needed flexibility and can be followed by the healthcare systems and patients," Golub said. "If TB is to ever be eliminated in the US, reducing TB among non-US-born persons must be prioritized."

The rifapentine used in the study was donated by Sanofi, the drug's manufacturer. Khan, Phares, and Golub reported no relevant financial relationships. The study was supported by a CDC Cooperative Agreement.

Emerg Infect Dis. 2022;28:582-590. Full text

For more news, follow Medscape on Facebook, Twitter, Instagram, and YouTube.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.