b) Socio-Cultural, Socio-Economic & Demographic Aspects
AU : Davies RPO, Tocque K, Bellis A, Rimmington T & Daview PDO
TI : Historical declines in tuberculosis in England and Wales: improving social conditions or natural selection?
SO : INT J TB & LUNG DIS 1999, 3, 1051-1054
DT : Per
AB :

Since there has been an association between TB, poverty and over-crowding, most observers assumed that during pre chemotherepeutic era, decline in mortality due to TB has been because of the improvement in social conditions alone. As per the records available from 1850, except during the world wars, mortality from TB has steadily declined. However, the possible effects of natural immunity acquired by successive generations in a process of natural selection and selective mortality of susceptible individuals or family are over looked in studies of historical TB rates. The aim of this study is to reinvestigate the association between changes in mortality from TB on the one hand and mortality from other poverty related diseases, socio-economic conditions and measures in Victorian England on the other. Mortality statistics for England and Wales from 1853 to 1910 (before world war) were obtained from the Registrar General Annual Reports. These publications included data on TB, cholera and dysentery. Infant mortality, total mortality rates, socio-economic measures, statistics on average real earnings were also taken from the same source. Data on other diseases over the same period of time were not as complete, hence not included for the comparison.

The results showed total mortality rates declined by 0.80 per year where as TB mortality declined by 1.71. The average annual declining for TB was therefore twice that for all causes. The infant mortality a closer indicator of improvement in social deprivation declined even more slowly by 0.58 per year. Secondly, while TB deaths showed a steadily improving trend over the 60 years, infant mortality improved only from 1900. The study showed that TB mortality declined at a much faster rate than any indicator of social deprivation improved for the period 1853 to 1910. It is therefore unlikely that social improvements alone were responsible for the remarkable steady decline in TB mortality. Other diseases such as diphtheria and cholera thought to be poverty related showed no similar decline. The decline in TB mortality far exceeded improvements in social conditions and other disease markers of poverty. Some other factors are likely therefore do have been playing a part, of which the most important is probably the process of natural selection.