the full quarantine regulations have been satisfied, the health officers of the several states to which the immigrants are bound are notified of the circumstances that they may keep close supervision to detect any later development of the disease.
Those vessels are placed in quarantine which have had quarantinable disease on board in transit or which the inspecting officer considers to be infected, also vessels arriving during the summer months from tropical American ports, which are not known to be free from yellow fever. Vessels in quarantine may have no direct communication with any person or place outside, and no communication of any nature except
under the supervision of the officer in charge. The persons detained from such a vessel are divided into small isolated groups, and inspected twice daily by the physician. No intercourse is allowed between these groups. No convalescents are discharged from quarantine until free from infection, and whenever possible this is determined by bacteriological examination.
The United States quarantine regulations provide for inspection of but six diseases, yellow fever, typhus fever, bubonic plague, leprosy, smallpox and cholera. A few facts relative to these will make plain the nature of the special precautions necessary to exclude them.
Yellow fever is the great sanitary curse of the tropical Americas. It is an acute non-contagious fever of unknown causation. Its extreme fatality is shown by a death rate which varies from 1 to 95 per cent. The causative agent, whatever it may be, is found in the patient's blood and is transferred to others by one agency alone, a certain type of mosquito, Stegomyia fasciata. The area where yellow fever is endemic corresponds exactly with the geographical distribution of the Stegomyia. It was due to the magnificent work of the Army Yellow Fever Commission in Cuba in 1898 that responsibility for the spread of the disease was definitely laid to the role of this mosquito. Too much honor can not be paid to those brave physicians who risked their lives to discover a
