The uncertainty, challenges, and variability in tuberculosis congregate setting investigations: The concentric circle model revisited

In the United States tuberculosis programs routinely conduct congregate setting contact investigations in locations such as schools, workplaces, social/recreational sites, nursing homes and prisons. Both documented and anecdotal reports describing these investigations have indicated, in many cases, the unnecessary testing of large numbers of individuals. This article revisits the concentric circle model and its application in congregate setting investigations. In its simplest form this model, despite imperfections, offers tuberculosis programs an opportunity to utilize this approach as a secondary tool to assist in the identification of contacts at both the highest and lowest level of risk due to exposure based on time and place to an infectious or potentially infectious patient. The methodology described here offers a prudent and viable alternative to not allowing a congregate setting investigation to be viewed as a general screening activity where excessive numbers of individuals are needlessly tested.