The Sartian Disease is a fictional illness from the popular TV series, The Expanse. The spelling of Sartian is derived from the pronunciation of the planet Mars in the story's futuristic universe, which is pronounced as "sahr-shun" (/sɑrʃən/ in IPA phonetics). The Disease is described as a deadly infection that spreads rapidly among the Mars colony, causing respiratory distress and ultimately leading to the victim's death. While the Sartian Disease is a work of fiction, it serves as a reminder of the dangers of rapidly spreading illnesses and the importance of vigilance in disease control.