“The leper in whom the plague is shall wear torn clothes, and the hair of his head shall hang loose. He shall cover his upper lip, and shall cry, ‘Unclean! Unclean!’ (NIV)
Clearly, the covering of the upper lip involved the whole mouth where the covering would lessen others being infected. The priest would examine the subject and rule for quarantines if the situation warranted. These instructions were directly given by God through Moses to abate the spread of disease in Israel. It seems that more than a few Christians could learn this lesson.