두창은 천연두의 옛 이름으로 전염력이 강하고 치사율이 30%를 넘으며, 회복되더라도 피부가 얽어 곰보가 되는 무서운 역병이었다.
Duchang was an old name for smallpox, which was highly contagious and had a fatality rate of more than 30 percent, and leaves a severe skin scars even after the recovery.