Louisiana’s top health official is warning researchers and medical professionals who’ve fought Ebola in West Africa to stay away from the American Society of Tropical Medicine and Hygiene’s annual conference in New Orleans, set to begin Sunday.

“We do hope that you will consider a future visit to New Orleans, when we can welcome you appropriately,” Kathy Kliebert, state Secretary of Health & Hospitals and Kevin Davis, director of the Office of Homeland Security & Emergency Preparedness, say in the Oct. 28 letter to the society.

Bloomberg News reported the letter “disinvites” anyone who has cared for Ebola patients within the last three weeks.

While Louisiana loves to welcome visitors, the state must balance hospitality with the protection of its residents and other visitors, the letter says.

Close to 3,600 people have registered to attend the annual conference, although the society doesn’t know how many of those have recently been in Liberia, Guinea or Sierra Leone, the countries where the Ebola outbreak has infected more than 13,000 people.