Pediatric Tuberculosis in the United States

Abstract & Commentary

By Hal B. Jenson, MD, FAAP, Dean, Western Michigan University School of Medicine, Kalamazoo, MI, is Associate Editor for Infectious Disease Alert.

Dr. Jenson reports no financial relationships in this field of study.

Synopsis: Three-fourths of US-born children with tuberculosis have lived in other countries (>2 months) or have an international connection in the immediate family, including 66% having at least one parent born outside of the US.

Source: Winston CA, et al. Pediatric and adolescent tuberculosis in the United States, 2008-2010. Pediatrics 2012;130:e1425-e1673.

An analysis was performed of incident cases of tuberculosis in the United States reported to the Centers for Disease Control and Prevention from 2008-2010. Beginning in 2009, data are now reported with additional epidemiologic information that helps identify links to another verified case of tuberculosis. Cases were epidemiologically linked by matching Mycobacterium tuberculosis genotypes based on spoligotype and 12-locus mycobacterial interspersed repetitive units, which are used routinely in national tuberculosis surveillance and have >95% discriminatory power.

Children and adolescents comprised 7% of all cases of tuberculosis reported in the US, with 977 cases in 2008, 865 in 2009 and 818 in 2010.

During 2008-2010, 822 (31%) were among foreign-born persons (not US citizens at birth) and 1826 (69%) were among US-born persons. For most (95%) foreign-born persons, the only country in which they had lived outside the United States was their country of birth. Foreign-born persons were older (11.0 years versus 5.5 years, P<0.0001) and more likely to have pulmonary disease (72% versus 67%). US-born persons were more likely to have extrapulmonary or combined pulmonary and extrapulmonary disease. Among persons with known HIV status, 1% of both US- and foreign-born persons were HIV-positive (P=0.58).

More than half (52%) of the US-born persons were Hispanic, compared with 30% of foreign-born persons. Among US-born persons, countries of birth for parents included the United States (35%), Mexico (29%), Guatemala (5%), India (4%), Vietnam (3%), El Salvador (3%), and Honduras (3%). Among foreign-born persons, countries of birth for parents included the United States (15%), Mexico (12%), the Philippines (10%), Burma (8%), Haiti (7%), and Somalia (6%). Most persons had at least one foreign-born parent, including 85% (169 of 198) of foreign-born persons and 66% (400 of 607) of US-born persons. Among US-born persons with only US-born parents, 43% were African-American.

Of 1680 persons less than 18 years of age with tuberculosis in 2009-2010, 201 (12%) were epidemiologically linked to at least one other person with tuberculosis in the US National Tuberculosis Surveillance database. Among the 188 US-born persons with epidemiologic links, 103 (55%) were linked to a foreign-born case. Among these US-born persons, 70% were initially evaluated for tuberculosis because there were contacts of a known case, with only 16% who sought medical attention because they were symptomatic. Among the 13 foreign-born persons with epidemiologic links, two (15%) were linked to a US-born case. All 13 foreign-born persons were evaluated for tuberculosis because they were contacts of a known case.

More than 96% of culture-positive persons had initial drug susceptibility testing results, with higher proportions of isoniazid resistance (11% versus 6%) and multidrug resistance (4% versus 1%) among foreign-born persons compared to US-born persons.

Commentary

This comprehensive nationwide survey of tuberculosis in children and adolescents in the United States underscores the impact of global tuberculosis on disease in the United States. Traditionally, African Americans born in the US are recognized as being at risk for tuberculosis, having eight times the rate of tuberculosis disease as white persons and being more likely to be latently infected with tuberculosis. This study identifies three additional groups of children and adolescents with an increased burden of tuberculosis: 1) US-born children with foreign-born parents; 2) foreign-born children with US-born parents; and 3) foreign-born adolescents. Healthcare providers should document the travel and living history, and clearly identify the country of birth of both the parents and the child when assessing tuberculosis risk in children. Three-fourths of US-born children with tuberculosis have lived in other countries (>2 months) or have an international connection in the immediate family, including 66% having at least one parent born outside of the US, compared with 18% for the general US-born pediatric population. The majority of foreign-born parents were from Mexico or Central America, where the prevalence of tuberculosis is higher. Non-Hispanic Asian and African American persons were also disproportionately represented among foreign-born persons and parents. Only 4% of persons were foreign-born with only US-born parents, which may reflect international adoption.

Foreign-born children should be evaluated for tuberculosis preferably before leaving their home country and again upon arrival in the United States. Testing is uncommon before immigration but recent modifications to US immigration guidelines now stipulate tuberculin skin testing for children 2-14 years of age, a group that previously was not often screened. Immigrant children who are negative for tuberculosis infection should be re-examined within six months of arrival in the United States and after any potential exposure to tuberculosis. Hence, entry into the US health care system is important for recent immigrants, which is frequently challenging.

The majority of foreign-born adolescents with tuberculosis were diagnosed after many years of residence in the United States. Healthcare providers should continue to monitor foreign-born adolescents for tuberculosis and not assume that latent tuberculosis infection was fully treated.

Drug resistance of M. tuberculosis remains a serious concern. Foreign-born children with foreign-born parents showed 18% prevalence of isoniazid resistance and 8% of multidrug resistance, compared to resistance of 6% and 0.4%, respectively, for all US-born cases. Drug susceptibility testing is imperative to guide tuberculosis prophylaxis and treatment regimens.