The season of mosquito prevalence begins in the Southern States in March and April and continues until November. Antimosquito measures should therefore be planned and begun in the winter months, but much depends upon their character and extent and the climatic conditions. The work should extend, for practical purposes, a quarter of a mile or more beyond the corporate limits or bordering residences to be benefited.

SCIENTIFIC STUDIES.

The laboratories at New Orleans have been equipped with microscopes, incubators, photographic apparatus, and many accessories for carrying on blood work and making practical and biological studies. Among the problems now being considered are:

1. Effects on malarial parasites of remedies in treatment.

2. Infectivity of the different species of Anopheles (punctipennis, quadrimaculatus, and crucians).

3. Life history of infected Anopheles in captivity.

4. Hibernation of infected Anopheles under artificial conditions. There are also several problems being considered in connection with measures for the control of malaria.

Types of infection. With a view to determining microscopically the types of malarial fevers prevailing in the State of Mississippi, a circular letter was sent to physicians representing every county in the State requesting them to furnish blood smears from their active and chronic cases, for which purpose slides, slide boxes, history blanks, and franks for mailing were furnished.

Of 428 blood specimens submitted and examined 225 were found positive, 132 of these being tertian, 91 estivo-autumnal, and 2 mixed. These were from 45 of the 79 counties in the State. In 11 counties only tertian infection was found, in 5 counties only estivo-autumnal, and in 29 counties both tertian and estivo-autumnal.

Malarial index work. Blood specimens for microscopic examination have been collected from a number of apparently healthy persons, selected at random, to determine the percentage, the malarial index, of persons in the community who harbor the parasite of malaria in their blood. The specimens were taken from persons who voluntarily submitted themselves. The examination of the specimens was made in the laboratory at headquarters.

Considerable interest has been manifested by the people in the various localities visited, as also by the State and local health officers, in this part of the work; and this interest was stimulated on account of the reporting of positive findings to individuals in order that they might seek appropriate treatment.

So far 13,526 blood specimens from localities in the States of Alabama, Arkansas, Mississippi, North Carolina, South Carolina, and Virginia have been examined, 1,797 of which proved positive. The percentage of infection found varied from 1.9 per cent in certain. localities to 40.9 per cent in Bolivar and Washington Counties, in the Yazoo Valley, Miss., where also the largest number of persons (1,666) were examined. The ages of the persons in whom infection was found ranged between 9 months and 85 years. The infection rate among white persons was about 8 per cent and among colored persons 20 per cent.

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PUBLIC HEALTH SERVICE.

Mosquito hibernation.-From February 2 to June 1, 1915, Technical Assistant M. B. Mitzmain was engaged in making special studies at Scott, Miss., of the hibernation of anopheline mosquitoes and the period of the year when infection of Anopheles occurs under natural conditions.

He dissected and examined 2,122 Anopheles and found that none of those that had undoubtedly hibernated was infected, and that the first infected mosquito found was on May 15, 1915. This is an observation of special importance for its bearing on determining the period of the year when quinine should be taken for prophylactic purposes. A report of this investigation has been published in the Public Health Reports and reissued as Reprint No. 290.

EDUCATIONAL MEASURES.

In the ordinary commercial towns, public interest must be aroused in order to create a demand for health work. Educational work must be conducted, and the people taught that the disease is preventable. It is an asset to any town to advertise its freedom from malaria, particularly in the Southern States.

Illustrated lectures were accordingly given by the different working parties at various places visited. For this purpose each field party was furnished with a slide-projection apparatus and a number of photographic slides illustrating the life of mosquitoes, parasites of malaria, and preventive measures such as ditching, oiling, screening, etc. The latter were reproductions of photographs taken at different localities visited during the progress of surveys.

Considerable general correspondence has been had with physicians and health officers in response to inquiries and requests for information regarding malarial fevers. Many requests are received for publications on the subject.

A very popular pamphlet is the catechism on the subject of malarial fevers, entitled "Malaria-Lessons on its Cause and Prevention," prepared by Asst. Surg. Gen. H. R. Carter, and published in July, 1914, as Supplement No. 18 to the Public Health Reports. A circular letter was sent to State health officers in the Southern States inviting attention to this publication and requesting that the school authorities should be urged to introduce it in the schools. Steps to this end have already been taken by the proper authorities in the States of Arkansas, Florida, Louisiana, and South Carolina.

Other publications issued during the year for educational purposes in connection with investigations of malaria are the following: Drainage As An Antimalarial Measure; Oiling As An Antimosquito Measure; and Anopheline Surveys, Methods of Conduct, and Relation to Antimalarial Work.

RICE CULTURE STUDIES.

To the extension of rice culture in certain sections has been attributed the increase of anopheles mosquitoes and a proportionate increase of malarial fevers. The only observations thus far made have been in the vicinity of Stuttgart, Ark. These studies will be continued to cover varying periods during the different steps in rice

culture; seasonable prevalence of mosquitoes in rice fields; habits of anophelines in relation to rice culture.

DRAINAGE PROJECTS.

Several of the Southern States are carrying out drainage projects for the reclamation of swamp lands. In the State of Tennessee the legislature recently authorized a bond issue of $400,000 for carrying out such a project, involving Dyer, Lake, and Obion Counties. The State health officer, Dr. R. Q. Lillard, made a request that in connection with the drainage work plans be included for the reduction or control of the malaria-bearing mosquitoes and thereby accomplish the double purpose of reclamation of lands, together with antimalaria work.

Accordingly a conference was held by Surg. von Ezdorf with Dr. Lillard in May, 1915, for the purpose of making arrangements to cooperate with the State board of health in the carrying on of antimalarial measures in connection with this project.

It is considered that the question has an important public-health aspect and that there will be a large field for work of this character in the Southern States where there are large areas of swamp land and where malarial fevers prevail to a considerable extent.

HEMOGLOBINURIA.

During the fall, beginning with the month of October and including the months of November, December, and January, hemoglobinuric fevers are reported in a number of places in the Southern States, where malaria prevails to a large extent. The relation of hemoglobinuria and malaria will be taken up as opportunity affords. From inquiries made at a number of places it appears that hemoglobinuria rarely occurs among negroes, although malarial fevers occur much more extensively among negroes than is generally believed.

IMPOUNDED WATERS.

The first suggestion in regard to the importance of making studies of the relation of impounding reservoirs to the prevalence of malaria was made by Asst. Surg. Gen. H. R. Carter when at Blewett Falls, N. C., in November, 1913. Consideration of this subject showed that in the Southern States it is estimated that over one hundred millions of dollars have been invested in impounding reservoirs to permit the use of water power for industrial purposes. The influence of these artificial bodies of water in the production of malaria is, however, a subject of complaint in many communities. In view of the variance of opinion on a subject of so much importance it was decided to undertake a comprehensive investigation with a view to determining the actual effects of this kind of ponds in producing malaria and suggesting adequate remedial measures.

The first actual studies were made by a field party headed by Dr. Carter at Hartsville, S. C., in July, 1914. Since then studies have been made of the following places: Blewett Falls, N. C., in July and September, 1914 (about 15 days in each month); Lock 12 on the

Coosa River, Ala., October 13 to November 19, 1914, by Sanitary Engineer Le Prince and Mr. J. V. Donley, engineer, Alabama State Board of Health, and in June, 1915; Parr Shoals, S. C., in July, 1914, and February 15-21, 1915; Georgia-Carolina Power Co., Savannah River, near Augusta, Ga., in February-March, 1915.

So far the following publications embodying the results of the investigations have been published: Impounded Water, Some General Considerations on its Effect on the Prevalence of Malaria; Impounded Waters, Survey at Blewett Falls; and Impounded Waters, a Study on the Coosa River.

The investigations contemplate the making of physical and zoological surveys, the first to determine whether the physical conditions are such as to make the places examined suitable breeding places for mosquitoes, and the second to determine what places are actually breeding malaria-bearing mosquitoes. In order to reach definite conclusions these studies will be prolonged for a number of years.

PELLAGRA INVESTIGATIONS.

Field investigations of pellagra were continued during the year under the direction of Surg. J. Goldberger. These investigations have been conducted at the marine hospital, Savannah, Ga.; Georgia State Sanitarium, Milledgeville, Ga.; Baptist Orphanage and Methodist Orphanage, Jackson, Miss.; and the State convict farm, Greenfield, Miss. In addition, insane asylums in Northern and Southern States have been visited to obtain pertinent data; field surveys made in a number of States, especially Arkansas, Florida, Louisiana, and Texas; and special clinical and laboratory studies undertaken at Spartanburg, S. C., and the Hygienic Laboratory, Washington, D. C. The following lines of research were followed during the year under the immediate direction of Dr. Goldberger: (1) Epidemiological studies at selected institutions; (2) studies of diet in relation to treatment; (3) feeding experiments to determine the value of diet in prevention.

EPIDEMIOLOGICAL STUDIES.

A number of observations show that although in many asylums new cases of pellagra develop in inmates even after 10, 15, and 20 years' residence, clearly indicating thereby that the cause of the disease exists and is operative in such asylums, yet at none has any one of the employees contracted the disease, though living under identical environmental conditions as the inmates and many in most intimate association with them.

In order to obtain precise data bearing on these observations, 12 asylums for the insane in Northern States were visited, the pellagra incidence in them investigated, and their dietaries compared with those of 14 asylums located in the South.

Milledgeville, Ga.-Studies of the records of the State Sanitarium at Milledgeville, Ga., dating from January 1, 1910, were continued by Assistant Epidemiologist D. G. Willets, under Dr. Goldberger's direction, in order to determine the rate of endemic prevalence of pellagra at this institution. The data already obtained show that 21 per cent of the deaths occurring in the sanitarium from 1910 to 1913 were caused by pellagra, the disease having been constantly highly

prevalent. On October 14, 1914, for instance, 253, or 6.7 per cent, of the 3,751 patients were pellagrins, and on June 19, 1915, 338, or 8.9 per cent, of the 3,796 patients. Out of 996 patients admitted in 1910, excluding those that died or were discharged during the year, or had pellagra on admission or within a year of admission, there remained after one year 418, and of this number 32, or 7.65 per cent, have developed pellagra after admission. In contrast with this fact, none of the employees living in substantially the same environment have developed the disease.

Jackson, Miss.-Similar studies at the Methodist Orphanage (since May, 1914) and the Baptist Orphanage (since September, 1914), Jackson, Miss., have been made and are being continued by Asst. Surg. C. H. Waring, under the direction of Dr. Goldberger. These studies include the occurrence of the disease among 450 persons residing at the two institutions, with consideration of all possible factors, such as drainage, sewerage, water supply, diet, etc.

At one of the two orphanages it was found that on July 1, 1914, out of 211 inmates 68, or 32 per cent, had pellagra. The age distribution showed that practically all these cases were in children between 6 and 12 years old. Inasmuch as all the orphans live under identical environmental conditions, the freedom from the disease shown by the older and younger, children constitutes a remarkable epidemiological fact.

At the other orphanage, out of a total population of 226 Dr. Waring found in September, 1914, 136 positive cases of pellagra and 24 with symptoms indicative of the disease.

Greenfield, Miss.-Studies of the effect of a one-sided diet have been conducted since January, 1915, at the State convict farm, Greenfield, Miss., in immediate charge of Asst. Surg. G. A. Wheeler and the supervision of Surg. Goldberger. These observations include the physical and mental condition of 12 inmates and the dietary of all the people on the farm, numbering over 90.

VALUE OF DIET IN TREATMENT.

From the earliest times it has been recognized that diet is an important element in the treatment of pellagra. Accordingly it was decided to determine scientifically the degree of its importance, and early in the fiscal year experiments to this effect by Special Expert W. F. Lorenz under the direction of Surg. Goldberger were begun in one of the wards of the Milledgeville Sanitarium, courteously opened to the service by the superintendent and board of trustees. Since September 1, 1914, when Dr. Lorenz severed his connection with the service, this work has been continued by Assistant Epidemiologist Willets. The experiment has consisted in furnishing to the patients in the ward the kind of diet which in the opinion of the service officers would be adequate to their condition. The number of patients receiving this diet has been 100, 80 of whom were pellagrins when the experiment was begun and 20 nonpellagrins. Of the pellagrins 73 have been constantly under observation. None of these pellagrins have given evidence of a recurrence of pellagra to this date.

A similar success followed the treatment of pellagra patients at the marine hospital, Savannah, Ga., with Passed Asst. Surg. J. R.