No person shall visit or enter any house wherein is any person sick with small pox or varioloid, except the persons who, at the time said patient was taken sick, were residents of said house, the nurse or nurses employed in the care of such patient and such regularly attending physicians as may be called; nor shall any person who is in constant attendance upon such sick person leave or depart from said house during the time when such sick person remains therein, and not thereafter until the wearing apparel which he or she has worn while in attendance upon such sick person shall have been replaced by clothing which has not been worn in such sickroom, and then only upon a written permit from the Health Commissioner. It shall be the duty of the Health Department to put up and maintain in a conspicuous place at the front entrance of any building, and also at any other entrance thereof, in which there shall be any person sick or infected with smallpox, varioloid, scarlet fever or diphtheria (or croup in any form) a card or sign on which shall be written or printed in English and German, Italian or Polish the words designating the infectious disease with which such sick person is affected and to keep the same so posted during all the time when such sick or infected person shall remain in said building. In any cases mentioned in this section, it shall be unlawful to remove or cause to be removed any such placard or notification of warning so placed by the Health Department; and in cases of diphtheria, such placard shall not be removed until bacteriological examinations shall have shown that no further danger from contagion exists; and no person shall, without the permission of the Health Commissioner, remove any such sign or placard so placed on any building. In case any such sign shall have been removed, either by accident or design, it shall be the duty of the person or persons occupying said building to notify the Department of Health thereof forthwith.