Rickets

Subclinical rickets reflects the same underlying deficiency and early skeletal impact as frank rickets but without overt presentation. Every one of the 25 confirmed Black Plague victims examined showed skeletal signs of rickets. Approximately 16% of a sample of infants with lower respiratory infections were found to have subclinical rickets. The universal presence of rickets in Black Plague victims reframes the pandemic as one that disproportionately killed people whose immune systems were already severely compromised by nutritional deficiency. Rickets is the clinical result of severe, chronic vitamin D deficiency. Rickets is caused primarily by vitamin D deficiency, though low calcium or low phosphorus can also contribute. In frank rickets, bones become soft and structural deformities develop. Wrist bone malformation is a detectable diagnostic indicator for subclinical rickets in infants.