An epidemiological approach to the analysis of cribra orbitalia as an indicator of health status and mortality in medieval and post-medieval London under a model of parasitic infection

Abstract

Objectives: Many individuals living in medieval and post-medieval London suffered issues with sanitation, food insecurity, infectious disease, and widespread exposure to parasites from a multitude of sources, causing increased risk of death for many inhabitants. We examine this stressful environment and its relationship with various demographic and temporal dimensions, using cribra orbitalia (CO) as an indicator of stress, to model an increased risk of dying under the expectations of our proposed parasitic model of infection. Materials and methods: We analyze the relationship between CO and mortality across seven medieval and post-medieval cemeteries from London by the covariates of sex, status, and age-at-death. A survival analysis (Cox regression) and a binomial logit estimated hazard and odds ratios of dying with CO across age-at-death, sex, status, and time-period within single statistical models. In addition, we provide new Bayesian age-at-death estimates for post-medieval samples. Results: The models show the rate of CO decreased over time and age-at-death, regardless of sex or status; post-medieval individuals were ~72% less likely to die with lesions than their medieval counterparts. Further, individuals with CO had ~1% decrease in risk of dying with CO per year of age. Discussion: These results suggest increased mortality risk for those with lesions indicative of anemia (CO), and selective mortality of younger individuals during the medieval period. Despite sex-specific nutritional and occupational hazards, and status-based access to resources, the prevalence of CO was similar across sex and status, which suggests living with parasitic infection that caused anemia was an everyday reality for medieval and post-medieval Londoners.