Approaches to co-occurrence: Scurvy and rickets in infants and young children of 16–18th century Douai, France

Disease co-occurrence is defined as the presence and interaction of multiple diseases in a single individual. The phenomenon occurred in the past, but detailed analyses of individuals affected by co-occurrence seldom appear. This paper presents 12 possible cases of scurvy and rickets co-occurrence from the Saint-Amé skeletal collection in Douai, France, dated to the 16–18th century. Each individual was evaluated for evidence of both diseases using macroscopic and radiographic techniques. Additional backscatter scanning electron microscopy evaluation for evidence of rickets was completed on a sub-sample of seven co-occurrence cases. Co-occurrence detection increased with the use of multiple techniques. No unique features identifying scurvy and rickets co-occurrence were observed; instead features associated with both diseases were present. Following clinical expectations, scurvy features were clearly developed while rickets features were subtle. Possible disease sequence and socio-cultural implications are suggested. The study’s findings are important to further research on disease co-occurrence as information on cases enhances our ability to understand site context.