Pop icon Justin Timberlake revealed he has Lyme disease, joining a growing list of celebrities who have gone public with their diagnoses.

As revealed in a vulnerable Instagram post just one day after his final show, the pop superstar had long been suffering from nerve pain and severe fatigue caused by Lyme that made him question whether he should stop touring.

As pop star Justin Timberlake shares his diagnosis of Lyme disease, his ordeal brings up questions. What is Lyme disease and its cause? How is the illness treated? A doctor explains.