Periarticular heterotopic ossification — bone forming in the soft tissue around a joint — is one of those conditions that tends to arrive without much warning. You might notice stiffness after a hip replacement, limited range of motion months after a spinal cord injury, or a strange firmness in tissue that was previously pliable.

For anyone who has lived in or traveled to a region where Schistosoma parasites are endemic — across much of sub-Saharan Africa, Brazil, parts of the Middle East, and Southeast Asia — the idea that a parasitic worm could be quietly fueling joint inflammation years after initial exposure is rarely on the radar.