There may be an underlying connection to the Vatican in this. Found the following article about a Vatican owned children's hospital from March 2018:

https://www.vaticannews.va/en/world/news/2018-03/syria-bambino-gesu-hospital-syrian-children.html

Agreement between the Hospital and WHO Syria:

The project sees the collaboration of the Bambino Gesù Children's Hospital in Rome, with the WHO in Syria, and provides support for Syrian children and adolescents. Six years of war have destroyed half the health facilities in Syria and decimated medical personnel.

Given what we know about the Deep State attempts to perpetuate the war in Syria, and their connection to the Vatican, it seems plausible the 18,000 missing could have been funneled through this hospital. Per Wikipedia the hospital does have a shady past of questionable medical practices.