Early studies on the prevalence of tuberculous infection among the poor and the rich in Asia (Hue in Vietnam) and Europe (Heidelberg in Germany and Trondheim in Norway) show large differences in the prevalence of tuberculous infection between these two population segments.
Consistently, the prevalence of tuberculous infection was much higher among the poorer than among the richer segments of the population. In fact, the differences within countries were larger than those between countries.
The most likely explanation for these differences lies in the fact that poverty forces crowded living conditions, thus the number of people exposed (and subsequently infected) if an infectious case emerges is larger in the poorer settings.
