Tuberculosis Transmission From a Foreign-Born Child

Abstract & Commentary

Synopsis: A 7-year-old boy moved from the Marshall Islands to North Dakota in 1996. A tuberculosis (TB) skin test was placed but not read. By the time he was diagnosed with cavitary TB in 1998, two contacts already had active TB, and 56 had developed positive TB skin tests.

Source: Curtis AB, et al. Extensive transmission of Mycobacterium tuberculosis from a child. N Engl J Med 1999;341: 1491-1495.

A 36-year-old woman was found to have tuberculosis (TB) arthritis of one hip joint without pulmonary involvement or infectivity. She had had no known contact with anyone with TB, lived in a part of North Dakota where TB is rare, and had only left North Dakota for a trip to Montana. Evaluating contacts, her 9-year-old child (who had joined the family from the Marshall Islands 2 years earlier) was found to have cavitary pulmonary TB. In retrospect, it was noted that the child sometimes fell asleep at school and had had a "dry cough" for a few months prior to diagnosis. After arriving in North Dakota two years earlier, a TB skin test had been placed but not read.

Careful evaluation suggested that the woman had probably contracted her infection in 1997. Thus, rigorous testing of the child’s other contacts was done. Three of four household contacts had positive skin tests (the guardian with TB in the hip, the twin brother with a positive sputum culture), as did 16 of 24 classroom contacts, 10 of 32 school bus riders, and nine of 61 day care contacts. Appropriate treatment was given.

Comment by Philip R. Fischer, MD, DTM&H

By conventional teaching, young children are not contagious for TB since they rarely generate a forceful enough cough to aerosolize and spread organisms. This child in North Dakota represents an alarming exception to conventional teaching. He not only had cavitary disease before being ill enough to prompt medical evaluation, but he had already spread active disease in his family and TB organisms to 20% of his contacts. Clearly, children in the first decade of life can spread TB.

Published recommendations1 can guide the evaluation of foreign-born children who are adopted into families in the United States. In particular, the history of having been vaccinated with BCG vaccine should not affect the decision about whether to place a TB skin test.1 The source patient in North Dakota had appropriately been subjected to TB skin testing, but the result of the skin test was never noted.

Policies vary for reading TB skin tests. Some health care providers require that results be read by medical personnel 48-72 hours after test placement, and others accept readings by presumably reliable patients or guardians. As sadly illustrated in North Dakota, providers should ensure that TB tests are not only placed but are also read and results documented. To facilitate this, medical offices should implement follow-up systems to confirm that tests are either read or repeated (and then read).

In addition to TB skin testing, what other evaluation should be done for adoptees and other children who are newly arrived in the United States? As reviewed in Travel Medicine Advisor Update in 1998,2 laboratory assessment could include tests for hepatitis B (both antigen and antibody testing), HIV, syphilis, and intestinal parasites. A blood count is also usually advised (with attention to anemia and to red cell indices). Increasingly, hepatitis C testing is also recommended since helpful treatment might be available. Assessments for normal, age-appropriate hearing, vision, dentition, development, and immunizations are also indicated. Though debatable, some experts recommend testing asymptomatic new arrivals for lead toxicity, thyroid dysfunction, and renal disease.

The source patient in North Dakota had his TB test placed "shortly after" arrival in the United States. When should TB testing be done in immigrants and foreign-born adoptees? Because some children coming into the United States could be in a "window" period between infection and conversion to a positive test, individuals testing negative initially could be retested six months later. Similarly, follow-up repeated testing for HIV and hepatitis C could be considered in children who tested negatively on arrival.3

The experience reported from North Dakota serves as a poignant reminder of the ability of M. tuberculosis to spread subtly through a community. Equally, the case demonstrates the public health implications of a missed screening opportunity. It also reminds us to carefully screen new arrivals in the United States. TB testing should be initiated and completed. Other testing, as adapted to the particular situation, should also be done. Follow-up is critical, and new arrivals must be integrated into the health care system.

References

1. American Academy of Pediatrics. Medical evaluation of internationally adopted children. In: Peter G, ed. 1997 Red Book: Report of the Committee on Infectious Diseases. 24th ed. Elk Grove Village, IL: American Academy of Pediatrics; 1997:116-120.

2. Hill DR. The health of internationally adopted children. Trav Med Advisor Update 1998;8:17-20.

3. Miller LC. Caring for internationally adopted children. N Engl J Med 1999;341:1539-1540.

Foreign-born adoptees arriving in North America:

a. should have monthly HIV testing until they have had two negative results.

b. should have TB skin tests placed only if they are symptomatic for TB.

c. should not have a TB skin test placed if they have received BCG.

d. should be carefully evaluated and screened for a variety of medical conditions.

e. should be vaccinated promptly in North America with BCG vaccine, if they have not been vaccinated already.