A respiratory virus that originates in the Middle East and has been hopscotching the globe for three years has today landed in yet another country, just as international health officials are raising concerns about the conditions that allow it to spread.

The virus is called MERS, Middle East Respiratory Syndrome coronavirus, and this morning Thai officials revealed that it has landed there via a medical tourist from the Persian Gulf state of Oman, who arrived in Bangkok to be treated for a heart condition. Three family members traveled with him, and all four are under quarantine, while passengers who sat near them on their flight are being sought and watched.

MERS originates in the Middle East (if you’d like to catch up, here are