Town population size and structuring into villages and households drive infectious disease risks in pre-healthcare Finland
Social life is often considered to cost in terms of increased parasite or pathogen risk. However, evidence for this in the wild remains equivocal, possibly because populations and social groups are often structured, which affects the local transmission and extinction of diseases. We test how the structuring of towns into villages and households influenced the risk of dying from three easily diagnosable infectious diseases—smallpox, pertussis and measles—using a novel dataset covering almost all of Finland in the pre-healthcare era (1800–1850). Consistent with previous results, the risk of dying from all three diseases increased with the local population size. However, the division of towns …
The seasonality of three childhood infections in a pre-industrial society without schools
AbstractBackgroundThe burden of many infectious diseases varies seasonally and a better understanding of the drivers of infectious disease seasonality would help to improve public health interventions. For directly transmitted highly-immunizing childhood infections, the leading hypothesis is that seasonality is strongly driven by social gatherings imposed by schools, with maxima and minima during school terms and holidays respectively. However, we currently have a poor understanding of the seasonality of childhood infections in societies without schools and whether these are driven by human social gatherings. Here, we used unique nationwide data consisting of >40 epidemics over 100 years…