The staff has consisted of Passed Asst. Surg. R. C. Derivaux, Asst. Surg. L. L. Williams, jr., Sanitary Engineer J. A. A. Le Prince, Technical Assistant M. B. Mitzmain, Asst. Epidemiologists T. H. D. Griffitts and J. C. Geiger, one clerk, one microscopist, and one attendant. SURVEYS. In accordance with requests received from State and local health authorities and other agencies field surveys were made to determine the nature and extent of the factors influencing the prevalence of malaria, and to ascertain the measures most applicable for their control. Other surveys for special investigations and to ascertain the progress of control campaigns instituted in previous years were also engaged in. The following is a list of places visited for purposes of survey or special investigation, and, in some instances, for educational lectures: Alabama: Talladega Springs. Arkansas: Crossett, Lake Village, Brinkley, Montrose, Hamburg, Little Rock, Texarkana. Georgia: Points in Tift, Irwin, and Sumter Counties, Brunswick, Waycross, Augusta, Atlanta. Illinois: Winnetka. Louisiana: Crowley, Clarks, Monroe, Baton Rouge, New Iberia, Lake Charles, De Ridder, Shreveport, Tallulah, Alexandria. Mississippi: Electric Mills, Cedars. Missouri: Crystal City, St. Louis, Illmo. North Carolina: Badin, Roanoke Rapids, Greensboro and vicinity, Lincolnton. Ohio: Toledo. Rhode Island: Providence. South Carolina: Fort Lawn, Stephens Creek, Chester, Columbia, Nitrolee. Tennessee: Memphis. Texas: Survey along lines of Cotton Belt Railroad, Dallas, Waxahachie, Sherman, Tyler, Lufkin, Marlin, Keltys. Virginia: Gilmerton, Dennys, Emporia, Wilson. DEMONSTRATION WORK. Roanoke Rapids, N. C.-As a result of continued activities at Roanoke Rapids, the site of the first demonstration of malaria control by antimosquito measures in the United States, a further reduction of malaria has been obtained, as shown by the following parasite indices obtained in October of each year: 1913, 13.75 per cent; 1914, 4.48 per cent; 1915, 3.51 per cent; and 1916, 0.53 per cent. This represents a reduction of 85 per cent in the last year and 96.15 per cent since the beginning of operations. Electric Mills, Miss.-A reinspection of the antimalaria work, begun in 1914 at Electric Mills, Miss., was made to determine the further result of control operations. The following parasite indices were obtained: 1914, 11.76 per cent; 1915, 3.79 per cent; and 1916, 1 per cent a reduction of 91 per cent. Cedars, Miss.-At Cedars, a lumber community so situated as to make control through Anopheles suppression impracticable, quinine was administered for immunization and sterilization, the following parasite indices being obtained: 1915, prior to control work, 33.6 per cent; 1916, 7.88 per cent a reduction of 76.55 per cent. Crystal City, Mo.-Reexaminations have been made of the effect of antimosquito measures at Crystal City and Festus. The endemic parasite index in 1915, prior to control work, was 5.62 per cent, and in 1916 was 0.92 per cent a reduction of 83.63 per cent. The influence of this work is well represented in the reduction of insurance claims paid for sickness disability on account of malaria: 1915, $230.22; 1916, $61.66; and 1917 (Jan. 1 to June 20), $6.66. Emporia, Va.-A repetition of the parasite index was made at Emporia, Va., to measure the degree of control gained by antimosquito measures. The index in 1915 was 9 per cent, and in 1916 3 -a reduction of 68.09 per cent. per cent Wilson, Va.-In conformity with recommendations by the service, malaria control work was undertaken at Wilson, Va. Before operations, it is stated that no homes were without one or more cases and in some all occupants were attacked. Five deaths from cerebral malaria are said to have occurred during August, 1915. In 1916 but one case of malaria was reported, and this case was said to have been a relapse. Demonstration work at other points. Similar work has been instituted at Montrose, Ark.; Dallas, Sherman, Waxahachie, and Marlin, Tex.; and along the lines of the St. Louis & Southwestern Railroad. COOPERATIVE DEMONSTRATION STUDIES WITH INTERNATIONAL HEALTH BOARD. As stated in the last annual report, a cooperative arrangement was entered into with the International Health Board through its director general, Mr. Wickliffe Rose, for the purpose of conducting a series of intensive demonstrations of malaria control and to study the relative values of the several control measures. For the purposes of this work, two localities were selected: (a) A town unit, at Crossett, Ashley County, Ark., for the intensive study of malaria control through the exclusive use of measures directed against mosquito propagation, and (b) A rural unit, consisting of a group of plantations in Chicot County, Ark., in the vicinity of Lake Village, where screening and quinine were employed. Active operations were begun in the two units in April, 1916, and completed in April, 1917, under the direction of a field director at each unit and under the immediate supervision of Asst. Surg. R. C. Derivaux. Crossett, Ark. The work included a survey and mapping of Crossett, which is a lumber community of 2,029 population (May, 1916), a study of the index of malaria prevalence by histories of infection and blood examination, and treatment of the various mosquito breeding places by ditching, filling, oiling, etc. No use was made of screening or quinine. About 10 miles of ditching were carried out and 1,350 gallons of oil used. By a comparison of the parasite indices taken prior to the beginning and after the termination of control operations, the following measure of gain is obtained: May, 1916, 9.43 per cent; December, 1916, 2.47 per cent-a reduction of 77.45 per cent. In 1915, 2,502 calls for malaria were made by physicians, and in 1916, 741 calls were made, a reduction of 70.39 per cent. If the malaria season alone is considered, the reduction is 82.07 per cent. The per capita cost of malaria control operations in Crossett, exclusive of those for administration and scientific study, was $1.23, or about $0.10 per month. Vicinity of Lake Village, Ark.-For the rural control studies, a group of 10 plantations with an aggregate of about 4,500 acres and 440 persons, 20.7 per cent white and 79.3 per cent colored, was selected. Each house or family was made a unit for control, and protection was given in one group through the use of carefully fitted screens and in another through the administration of quinine in immunization doses (for adults, 10 grains on two successive days per week). In both groups all malaria carriers were given intensive treatment for sterilization purposes (10 grains daily for 30 days). Thirty-three houses were experimentally screened and systematic observations made through the year as to the efficacy of the screening and the health of the occupants. The average cost for screening per house was found to be $14.22, of which $8.11 was for labor and $6.11 for materials. The life of the screens was believed to be at least two years. Parallel observations by systematic inspections were similarly conducted in the group of individuals to whom quinine had been issued and, in addition, in a "negative control" unit of 120 colored persons living on two near-by plantations. In this latter group, in which a parasite index of 21.84 per cent was obtained, no malaria control measures were employed. The reduction for all groups as illustrated by repetition of the parasite index is shown in the following summary: Among the occupants of the screened houses alone the first parasite index findings were 11.97 per cent, and in the second 3.52 per cent, the reduction obtained being 70.06 per cent. At the beginning of operations quinine was issued to 69 persons for sterilization and to 237 for immunization. Among those to whom it was issued for immunization a reduction in the parasite index of 64.45 per cent was obtained, and to those to whom it was administered for sterilization a reduction in the numbers of carriers found at the first index was 68.12 per cent. Among the carriers observed throughout the season the reduction effected was 95.17 per cent. A comparative study of the average costs for physicians' calls and drugs for malaria, losses of time through sickness, etc., in the groups in which protective measures were used in contrast with similar economic losses in the negative control group is summarized below: The details of the experiment at Crossett and Lake Village and the results obtained have been embodied in a report and published as Public Health Bulletin No. 88. As shown by the chart on page 23, the results were remarkable. In fact, so clear were they that the community affected has continued the work in a highly satisfactory manner. Probably no more definite antimalaria demonstration has ever been made, certainly not in America; and if it is repeated (as it can be) in other sections of the country, the Federal Government will have contributed generously to the campaign for the control of malaria. Hamburg, Ark.-In cooperation with the International Health Board, the service has commenced a second demonstration of mosquito control, similar to that at Crossett, at the neighboring town of Hamburg, the county seat of Ashley County. The results have not yet been determined. EDUCATIONAL MEASURES. As in previous years, educational and explanatory lectures have been delivered in connection with surveys made and conferences held for the institution of control campaigns. Every effort has been made to enlist the active interest and intelligent cooperation of physicians and people in the various communities by illustrated talks, demonstrations and field trips, and, as heretofore, educational work has been carried on in schools in connection with the collection of material for determining parasite indexes. SCIENTIFIC STUDIES. Infectibility of Anopheles punctipennis. In a further series of studies with A. punctipennis conducted by Technical Assistant M. B. Mitzmain, 52 specimens were allowed to feed upon blood containing Plasmodium falciparum (subtertian malaria), and 14 infections were obtained. In a previous study with these species only negative results were secured. Distribution of Anopheles and disappearance of infection.-Additional evidence has been obtained to indicate that A. quadrimaculatus exhibits a much greater tendency to invade the interior of dwellings than does A. punctipennis, and it is suggested that the more sylvan attributes of the latter may render its relation to the transmission of malaria of less sanitary importance. A seasonal study was conducted at the same time to determine the approximate date of disappearance of infected Anopheles under field conditions. The last infected example, an A. quadrimaculatus, was taken on November 15 (at Talladega Springs, Ala.).1 Effect of temperature on development of malaria parasites in mosquito. In a series of studies conducted with Anopheles under artificially maintained low temperature, inhibition and cessation of development of parasites were observed. It is suggested by these results that intermittent low temperatures may so interfere with sporozoite development as to render infected mosquitoes innocuous at an earlier part of winter than has been heretofore supposed.2 1 Brief report published. (Reprint 393 from Public Health Reports.) |