exist unless the shipment is accompanied by a certificate that the animals are free from wood ticks. The transportation of persons suffering from plague, cholera, yellow fever, smallpox, typhus fever, scarlet fever, poliomyelitis (infantile paralysis), Rocky Mountain spotted or tick fever, and epidemic cereobro-spinal meningitis, is prohibited. Specific regulations are provided governing the transportation of persons suffering from typhoid fever, diphtheria, whooping cough, measles, tuberculosis, leprosy, and venereal diseases. The only general regulation, in addition to those affecting interstate carriers, is the one providing that camps of migratory workers must be kept in a proper sanitary and vermin-free condition.

The control over water for drinking purposes used by interstate carriers is effected by requiring the carrier to use water from a source which is certified and approved as producing water of satisfactory sanitary quality and safety. These certificates may be issued by officers of the Public Health Service or by the state department of health having jurisdiction over the supply, and must be filed whenever the Surgeon General of the Public Health Service may direct but not less than semi-annually, in March and September of each year. These certificates are based upon the relative freedom of the water "from contamination or exposure to contamination, by micro-organisms and substances recognized as harmful or deleterious to the consumer's health or liable to spread infectious or contagious disease, as determined through a survey of the sanitary conditions under which the supply is produced and the results of bacteriological and chemical analysis of samples of the water."4 During the fiscal year 1920 interstate carriers obtained water for drinking purposes from 2990 sources of supply, of which 2111 were found satisfactory and 243 polluted. No determination was made of the character of the water from the remaining 636 sources. As interstate carriers generally use municipal water supplies the super

4

* Amendment No. 8 to Interstate Quarantine Regulations, July 14, 1919.

vision of the water used by them often indirectly results in improvement in the character of the water used by municipalities.

Sanitary engineering work. As the most effective method of preventing the interstate spread of disease is to eliminate sources of infection within the states, the Public Health Service has supported the state authorities in establishing and developing divisions of sanitation for the study of water, sewage, and other public health engineering problems. During the fiscal year 1920 the Public Health Service assisted in building up the engineering work of the public health departments of eleven states by furnishing the services of trained sanitary engineers. These officers make specific investigations of water supplies and sewage disposal problems, and organize or make recommendations regarding the establishment of sanitary engineering divisions. The aim of the Public Health Service is not to work out all the problems involved in local sanitary measures but to render assistance in planning the most urgent work and to point out the desirability of having a definite organization to carry on such work continually. Very largely as a result of the work done by officers detailed from the Public Health Service new sanitary divisions were organized during the fiscal year 1920 in eight states.

Control of Epidemics. While the Secretary of the Treasury has power under the act of February 15, 1893, to declare a general quarantine prohibiting interstate traffic from moving from communities where contagious disease is prevalent it has not been found necessary to exercise this power within recent years. During the epidemic of poliomyelitis in the fall of 1916 a modified form of quarantine was put into effect in the principal centers of the disease by requiring the railroad companies to refuse interstate transportation to children under sixteen years of age who did not possess an identification certificate issued by the Public Health Service. This certificate was made in duplicate and one copy was mailed to the local authorities at the place of destination, so that they might keep

in touch with all children coming from infected areas.

This certificate of identification did not compel local authorities to allow children to detrain, but after the first panic had passed the local authorities generally recognized that the plan adopted was sufficient to prevent the spread of the disease.5

The epidemic of influenza of 1918 called for an entirely different line of effort. This disease could not be combated by even a modified quarantine and efforts were limited to supplying information and to organizing the work of communities in advance of the height of the epidemic.

During the several epidemics of bubonic plague that have visited seaport cities in recent years the greatest stress has been placed upon local measures of sanitation, particularly the destruction of rats and ground squirrels, which are carriers of the disease. Under the federal law a quarantine might have been declared against the port at which the disease existed, but it was recognized that the interference with commerce resulting from a quarantine would cause immense losses." Instead of quarantining such ports and forcing the local authorities to bear all the expense of remedial measures, it was deemed advisable to cooperate with the local authorities or to undertake entirely the trapping of rats and other carriers of the disease. Pressure was also brought to bear upon the local authorities to require all buildings to be made ratproof.

Plague suppressive measures were carried on during the fiscal year 1920 at San Francisco, Oakland, Berkeley, and the surrounding area; New Orleans, Pensacola, Galveston, Beaumont, and Seattle.

In the case of the better known communicable diseases aid is given to states with the idea of building up a strong division of communicable disease control in each state health department rather than to expand federal activities. The work of

5 Surg. Gen., Annual Report, 1917, p. 189 et seq.

6

Hearings before House Committee on Appropriations on Sundry Civil Bill for 1921, p. 37.

the service is based on the principle that the prevention of the spread of diseases is best effected by exercising remedial measures in the early days of an epidemic. To accomplish this it is necessary to establish an endemic index; that is, the normal rate of prevalence of each disease. The second step is to obtain prompt, frequent, and reliable reports of morbidity or the occurrence of the discase. By comparing the morbidity reports with the endemic index, the state health officer can readily see whether any particular disease is prevalent to an abnormal degree, and can take steps to control the disease before the epidemic becomes widespread. In many states an endemic index has not been established and morbidity reports are meager or unreliable. The development of adequate local machinery is therefore the most important step to be taken in preventing the spread of disease. Assistance to local authorities is extended in order to aid in the establishment of better reporting systems, and to give state and local officers the benefit of the wider experience of the national service in making an analysis of the causes of epidemics and pointing out the remedial measures necessary.

Medical Inspection of Immigrants. The medical inspection of immigrants was begun by the service in the early part of 1890, when this work was undertaken at New York, by direction of the Secretary of the Treasury under the provisions of the act of August 3, 1882 (20 Stat. L., 214). The act of March 3, 1891, made more specific provision for the medical examination of aliens and placed this duty definitely on the Marine Hospital Service. The inspection of immigrants at foreign ports was begun in 1889. A second act providing for the medical examination of aliens was passed on March 3, 1903 (32 Stat. L., 1213-1222). The authority for this work at the present time is contained in sections 3 and 16 of the act of February 5, 1917 (39 Stat. L., 875-885). The classes denied admission by section 3 are "idiots, imbeciles, feeble-minded persons, epileptics, insane persons, persons who

have had one or more attacks of insanity at any time previously, persons of constitutional psychopathic inferiority, persons with chronic alcoholism, . . . persons afflicted with tuberculosis in any form or with a loathsome or dangerous contagious disease, [and] persons not comprehended within any of the foregoing classes who are found to be and are certified by the examining surgeon as being mentally or physically defective, such physical defect being of a nature which may affect the ability of such alien to earn a living." This work includes the medical examination of all alien seamen, regardless of whether they desire to land or not.

Section 16 of the act requires the physical and mental examination of arriving aliens to be made by medical officers of the Public Health Service, who have had two years' experience in the practice of their profession since receiving the degree of doctor of medicine. If, however, medical officers of the Public Health Service are not available, civil surgeons may be employed by the Commissioner General of Immigration, who has general supervision over the admission of immigrants and has direct charge of all examinations that are not physical or mental.

"7

It is the function of the proper immigration officers of the Department of Labor "to determine whether an alien may belong to any one or more than one of the excluded classes." It is the duty of medical officers of the Public Health Service to submit to the immigration officers evidence of two kinds : (1) certification as to findings of fact and (2) testimony in the form of professional opinions. For instance the question whether an alien has a particular defect or disease "is purely medical and is therefore for the medical officer to determine; the question of the effect of such a disease on the alien's earning capacity is a practical one, and therefore for the immigration officer to determine, although such immigration officer may desire, and having obtained, may consider

7 Regulations governing the Medical Inspection of Aliens, Public Health Service Miscellaneous Publication No. 5, 1917, p. 6.