Title: Changes in mortality by TB in non-industrialized Coimbra (Portugal): Trends between 1861 and 1914

Authors: Ana Luisa Santos¹, Bruno M. Magalhães¹, Cinzia Roggio²

Affiliations: ¹CIAS (Centro de Investigação em Antropologia e Saúde), Department of Life Sciences, University of Coimbra, Coimbra, Portugal; ²Universita’ Degli Studi di Sassari, Sassari, Italy

Abstract: Considering that before antibiotics and vaccination the course of tuberculosis (TB) depended mostly of the immune response of the patient, this study tested the hypothesis that mortality profile remained similar in the transition between 19th and 20th centuries.

To fulfil this aim, the records of the Coimbra Municipal Cemetery of Conchada were studied. At the time, this non-industrialized city was the fifth most populated in Portugal. Biographic information – sex, age at death, type of TB, and month, and year of death – of the individuals born in the city and with TB as cause of death were analysed using SPSS.

The years of death were grouped in three periods: 1861–1870 (n=124, 22.5%), 1871–1880 (n=234, 42.4%), and 1910–1914 (n=194, 35.1%). These numbers shown an increase of mortality by tuberculosis (last period comprises only 5 years). A total of 552 individuals, 242 females (43.8%) and 310 males (56.2%) died of TB, with statistically significant difference between sexes (p<0.05). The mean age at death (ranging from 11 days to 86 years) decreased over time, respectively 51.8, 53.1 and 35.8 years old for individuals older than 20.

Deaths by pulmonary TB (n=38 in 1861–1870, n=115 in 1910–1914) and meningeal TB (n=0 in 1861–1870, n=48 in 1910–1914) increased over time while scrofula decreased considerably (n=23 in 1861–1870, n=3 in 1910–1914). These trends could be biased by the improvement of TB diagnosis after the identification of the Koch’s bacillus in 1882 and the reduction of the use of the general denomination tuberculosis (n=58 in 1861–1870, n=11 in 1910–1914) as cause of death. Interestingly, in paleopathology, the identification of TB is mainly based on bone and joint type, however only a 12 years-old male (0.2%, 1/552) died with a white tumour in the knee.

Seasonality of mortality was observed in infants (0–3 years-old), 50.5% (48/95) of the individuals died between July–October.

These results showed that the hypothesis presented was false, death by tuberculosis increased in the period under analysis which may be a consequence of population growth and/or deterioration of the living conditions and/or changes in bacterial virulence and/or host immune system.