Epidemiology of extra-pulmonary tuberculosis in the United States: high rates persist in the post-HIV era

Background The incidence of tuberculosis (TB) in the United States has declined following a logarithmic pattern, with few exceptions. One exception was during the acquired immunodeficiency syndrome (AIDS) epidemic, which was thought to have caused the deviation. However, since then, alternative explanations have been proposed, including the increased burden of chronic diseases, immigration, and the increase in the use of immune suppressant medications. Methods Epidemiological data of the Center for Disease Control and Prevention (CDC) and the Bureau of the Census were analyzed regarding TB incidence, human immunodeficiency virus (HIV) infection, immigration status, and age for the period 1953-2011. Results Data analysis identified a deviation from the logarithmic decline in TB cases that started in the mid-2000s. This divergence did not appear to be related to HIV status. The overall decline in TB cases since 1953 has been almost exclusively due to a reduction in pulmonary TB (PTB) and not to extra-pulmonary TB (EPTB). Conclusions The HIV/AIDS epidemic likely played a significant role in the 1979-1985 deviation, but not subsequently. Furthermore, EPTB as a proportion of total TB cases has remained high. Further studies to delineate the etiologies of these findings are needed.