Urban inoculation and the decline of smallpox mortality in eighteenth-century cities-a reply to Razzell

Mortality, migration and epidemiological change in English cities, 1600-1870

OBJECTIVE

This study tests the argument that industrialisation was accompanied by a dramatic worsening of urban health in England.

MATERIALS

Family reconstitutions derived from baptism, marriage and burial records for the period before 1837, and from civil registration of deaths and census populations between 1837 and 1900.

METHODS

Age-specific mortality rates are used as indicators of population health.

RESULTS

The available evidence indicates a decline in urban mortality in the period c.1750-1820, especially amongst infants and (probably) rural-urban migrants. Mortality at ages 1-4 years demonstrated a more complex pattern, falling between 1750 and 1830 before rising abruptly in the mid-nineteenth century.

CONCLUSIONS

These patterns are better explained by changes in breastfeeding practices and the prevalence or virulence of particular pathogens than by changes in sanitary conditions or poverty. Mortality patterns amongst young adult migrants were affected by a shift from acute to chronic infectious diseases over the period.

SIGNIFICANCE

Pathogen evolution, infant care and migration exerted major influences on mortality trends and should be given greater attention in studies of the health impacts of British industrialisation.

LIMITATIONS

Evidence of urban mortality rates is very limited before 1837 and may not be fully representative of industrialising populations. Mortality also provides only a partial picture of the health of urban populations and may be distorted by migration patterns.

FURTHER RESEARCH

There is enormous scope for collaboration between archaeologists and historians to investigate the health of industrial populations, through the triangulation and contextualisation of diverse sources of evidence.

Patterns of smallpox mortality in London, England, over three centuries

Smallpox is unique among infectious diseases in the degree to which it devastated human populations, its long history of control interventions, and the fact that it has been successfully eradicated. Mortality from smallpox in London, England was carefully documented, weekly, for nearly 300 years, providing a rare and valuable source for the study of ecology and evolution of infectious disease. We describe and analyze smallpox mortality in London from 1664 to 1930. We digitized the weekly records published in the London Bills of Mortality (LBoM) and the Registrar General's Weekly Returns (RGWRs). We annotated the resulting time series with a sequence of historical events that might have influenced smallpox dynamics in London. We present a spectral analysis that reveals how periodicities in reported smallpox mortality changed over decades and centuries; many of these changes in epidemic patterns are correlated with changes in control interventions and public health policies. We also examine how the seasonality of reported smallpox mortality changed from the 17th to 20th centuries in London.

Variola virus genome sequenced from an eighteenth-century museum specimen supports the recent origin of smallpox

Smallpox, caused by the variola virus (VARV), was a highly virulent disease with high mortality rates causing a major threat for global human health until its successful eradication in 1980. Despite previously published historic and modern VARV genomes, its past dissemination and diversity remain debated. To understand the evolutionary history of VARV with respect to historic and modern VARV genetic variation in Europe, we sequenced a VARV genome from a well-described eighteenth-century case from England (specimen P328). In our phylogenetic analysis, the new genome falls between the modern strains and another historic strain from Lithuania, supporting previous claims of larger diversity in early modern Europe compared to the twentieth century. Our analyses also resolve a previous controversy regarding the common ancestor between modern and historic strains by confirming a later date around the seventeenth century. Overall, our results point to the benefit of historic genomes for better resolution of past VARV diversity and highlight the value of such historic genomes from around the world to further understand the evolutionary history of smallpox as well as related diseases. This article is part of the theme issue 'Insights into health and disease from ancient biomolecules'.

An introduction to the history of infectious diseases, epidemics and the early phases of the long-run decline in mortality

This article, written during the COVID-19 epidemic, provides a general introduction to the long-term history of infectious diseases, epidemics and the early phases of the spectacular long-term improvements in life expectancy since 1750, primarily with reference to English history. The story is a fundamentally optimistic one. In 2019 global life expectancy was approaching 73 years. In 1800 it was probably about 30. To understand the origins of this transition, we have to look at the historical sequence by which so many causes of premature death have been vanquished over time. In England that story begins much earlier than often supposed, in the years around 1600. The first two 'victories' were over famine and plague. However, economic changes with negative influences on mortality meant that, despite this, life expectancies were either falling or stable between the late sixteenth and mid eighteenth centuries. The late eighteenth and early nineteenth century saw major declines in deaths from smallpox, malaria and typhus and the beginnings of the long-run increases in life expectancy. The period also saw urban areas become capable of demographic growth without a constant stream of migrants from the countryside: a necessary precondition for the global urbanization of the last two centuries and for modern economic growth. Since 1840 the highest national life expectancy globally has increased by three years in every decade.

Urbanization and mortality in Britain, c. 1800-50

In the long-running debate over standards of living during the industrial revolution, pessimists have identified deteriorating health conditions in towns as undermining the positive effects of rising real incomes on the 'biological standard of living'. This article reviews long-run historical relationships between urbanization and epidemiological trends in England, and then addresses the specific question: did mortality rise especially in rapidly growing industrial and manufacturing towns in the period c. 1830-50? Using comparative data for British, European, and American cities and selected rural populations, this study finds good evidence for widespread increases in mortality in the second quarter of the nineteenth century. However, this phenomenon was not confined to 'new' or industrial towns. Instead, mortality rose in the 1830s especially among young children (aged one to four years) in a wide range of populations and environments. This pattern of heightened mortality extended between c. 1830 and c. 1870, and coincided with a well-established rise and decline in scarlet fever virulence and mortality. The evidence presented here therefore supports claims that mortality worsened for young children in the middle decades of the nineteenth century, but also indicates that this phenomenon was more geographically ubiquitous, less severe, and less chronologically concentrated than previously argued.

Infant-feeding practices and infant survival by familial wealth in London, 1752-1812

Anecdotal evidence indicates that high-status women in England generally did not breastfeed their children in the seventeenth and early eighteenth centuries. Metropolitan families of varied social status also often sent their children out of London for wet-nursing. However, anecdotal sources and rural burial registers also suggest that these practices declined rapidly from the mid-eighteenth century, and were replaced by a culture of maternal breastfeeding in all social classes. These changes in infant-feeding practices have been argued to explain much of the dramatic improvement in infant mortality rates in London in this period. Here we used quantitative evidence from a partial family reconstitution of the London parish of St. Martin in the Fields to test these claims. Using birth interval analysis to infer breastfeeding patterns in families by four categories of wealth, we found that birth intervals were close to the national average in pauper and poor families, but much shorter in wealthier families, in the period 1752-74. We also found evidence that many infants especially in wealthier families were missing from observation, consistent with high levels of rural wet-nursing. Both these phenomena declined between 1775 and 1812, suggesting a convergence in breastfeeding practices to the national norm. We used event history analysis, with corrections to aggregate rates for missing infants, to compare mortality rates over time and by wealth category. We found that infant mortality was initially higher in wealthier families, but declined in all groups over the period 1752-1812. We conclude that increases in maternal breastfeeding were probably important in improving survival of infants from wealthier families, however changes in breastfeeding patterns were insufficient to account for the ubiquitous improvements in mortality of urban-born infants in this period.

The geography of smallpox in England before vaccination: A conundrum resolved

Smallpox is regarded as an ancient and lethal disease of humans, however very little is known about the prevalence and impact of smallpox before the advent of vaccination (c.1800). Here we use evidence from English burial records covering the period 1650-1799 to confirm a striking geography to smallpox patterns. Smallpox apparently circulated as a childhood disease in northern England and Sweden, even where population densities were low and settlement patterns dispersed. However, smallpox was a relatively rare epidemic disease in southern England outside the largest cities, despite its commercialised economy and the growing spatial interconnectedness of its settlements. We investigated a number of factors hypothesised to influence the regional circulation of smallpox, including exposure to naturally occurring orthopox viruses, settlement patterns, and deliberate preventative measures. We concluded that transmission was controlled in southern England by local practices of avoidance and mass inoculation that arose in the seventeenth and eighteenth centuries. Avoidance measures included isolation of victims in pest houses and private homes, as well as cancellation of markets and other public gatherings, and pre-dated the widespread use of inoculation. The historical pattern of smallpox in England supports phylogenetic evidence for a relatively recent origin of the variola strains that circulated in the twentieth century, and provides evidence for the efficacy of preventative strategies complementary to immunisation.