Given the number of immigrants from Third World countries, why are medical providers still teaching that BCG vaccine provides lifelong protection against TB? Similarly, why are providers not treating latent TB infection when we have so many people from at-risk populations in the United States?—SISTER MARILYN DUNN, FNP, Bardonia, N.Y.

Providers who teach that BCG provides lifelong immunity against TB are incorrect. According to the CDC and the World Health Organization, at best BCG provides a degree of immunity largely to small children and often merely mitigates the severity of the disease rather than preventing it completely. BCG is rarely used in the United States and is not the standard of care in prevention. However, many immigrants from Third World countries may have been vaccinated with BCG at some point. TB skin tests will remain positive from a BCG injection for up to 15 years. The CDC says that high-risk patients with positive skin test and/or chest x-ray should be assumed to have latent disease and treated actively, in spite of previous BCG injections. —Sherril Sego, FNP-C, DNP (146-8)