Historical declines in tuberculosis in England and Wales: improving social conditions or natural selection?

Abstract

Objectives: A reinvestigation of the relationship between the decline of tuberculosis and improvement in social conditions in England and Wales during Victorian times.

Design: A retrospective study using data published in the annual reports of the Registrar General from 1853 to 1910. MEASURES ASSESSED: The diseases studied, in addition to tuberculosis were dysentery and cholera, including their total and infant mortality. Social conditions were evaluated from earnings and population density per house.

Results: Tuberculosis mortality declined at an annual average rate of 1.71% (95% confidence interval [Cl] 0.77-2.63), whereas total mortality, infant mortality and mortality from cholera and dysentery and house population density showed no statistically significant decline over the same period. Real earnings increased by 1.05% (95% CI 0.29-1.81).

Conclusion: Improving social conditions do not provide the total explanation for the decline in tuberculosis during Victorian times. Other factors, principally natural selection, probably played a role. Part of the current increase in tuberculosis may be caused by effective drug therapy eliminating natural selection.