may examine any person who proposes to embark thereon if he has reasonable grounds for believing him to be suffering from a disease subject to the International Health Regulations or from lassa fever, viral haemorrhagic fever or marburg disease and, if after examination the medical officer is of the opinion that he shows symptoms of such a disease, shall prohibit his embarkation and the time and place of this examination shall be arranged to take into account any other formalities and to avoid delay;

shall prohibit any suspect from embarking thereon:

Provided that in the case of smallpox a person shall not be prohibited from embarking if he satisfies the medical officer that he is sufficiently protected by vaccination or by a previous attack of smallpox;

shall notify by the most expeditious means the master and, also, the health authority for the place to which the person is proceeding of any person embarking or proposing to continue his voyage thereon who, in the opinion of the medical officer, should be placed under surveillance;

notwithstanding the provisions of sub-paragraph (b) of this regulation may allow a person on an international voyage who, on arrival, was placed under surveillance to continue his voyage. The medical officer shall notify by the most expeditious means the health authority for the place to which the person is proceeding that such a person should, in the opinion of the medical officer, be placed under surveillance.