URBAN-RURAL VARIATIONS IN TUBERCULIN SENSITIVITY

Publisher Website
Google Scholar
Abstract
A 10% population sample was drawn from Wilson County by random means. Ninety-three per cent of this sample was tested with 5 TU of PPD-S. With the exception of nonwhite men, the urban population was found to have higher tuberculin rates than the rural. Nonspecific reaction rates, as shown by the incidence of small indurations, were higher in the rural population than in the urban and were most marked among the non-whites. This gave rise to the assumption that the causative organisms postulated to cause this reaction were localized in distribution, being associated most commonly with the rural area. A model was proposed for estimating the percentage of tuberculin reactors in a community. This model is based on the assumption that tuberculin reactors tend to cluster symmetrically about a mode or mean, and is expressed by the following formula For per cent positive [image].