LOUSE POWDER STUDIES IN NORTH AFRICA (1943) by F. L. SOPER, W. A. DAVIS, F. S. MARKHAM, L. h. fillsHL and Paul BUCK INTRODUCTtON Severe and extensive outbreaks of typhus fever occurred in both Algiers and Morocco during the winters of 1941-1942 and 1942-1943. A survey visit to this area by Mr. Richard ALLEN of the American Red Cross, and Dr. George X. STRODE of the International Health Division of the Rockefeller Foundation in January 1943 led to negotiations with Dr. Edmund SERGENT, Director of the Pasteur Insti?ute of Algiers, with Dr. G~ENOILLEALJ, Director of Health for Algeria, and Dr. GAUD, Director of Health for Morocco,, for colla- boration in studying methods of typhus control, based on the use of insecticidal powders. The American Red Cross sponsored the studies which were undertaken with the approval of the State Department. The Rockefeller Foundation Health Commission assigned Doctors Fred L. SOPER, William A. DAVIS, Floyd S. MARKHAM and Louis A. RIEHL to the project. Through tramportation facilities provided by .the War Department an the Surgeon General's Office this group came to North Africa late in June 1943 and established contact with the Pasteur Institute of Algiers, the Health Department of Algeria and the Medical Section of NATOUSA. Plans were made for the initial testing of materials and methods in collaboration with the Pasteur Institute of Algiers. Demonstra- tions of epidemic control measures were planned in both Morocco and Algeria, if epidemic typhus again became a serious problem during the ensuing winter season. The initial activities were devoted to : (1) evaluating the effecti- veness of different louse powders on natural infestations ; (2) study- ing locally available excipients for the preparation of louse powder; (3) testing the feasibility of mixing DDT powder in the field ; (4) determining the duration of effect of insecticides in the face of constant reinfestation ; (5) developing methods for the rapid 184 F. L. SOPER, W. A. DAVIS, F. S. MARKHAM, L. A. RIEHL, P. BUCK application of powder to the individual ; and (6). developing admi- nisti-ative metho,ds for rapidly and economically delousing com- munities for the purpose of blocking the spread of epidemic typhus. Considerable difficulty was encountered in securing adequate supplies, transportation and personnel for the ffeld studies, tifid the program proceeded more slowly than had been anticipated. How- ever, during the following months the initial testing of materials and methods in a civilian prison was completed, and field demons- trations of delousing without the removal of the clothing had been made in Prisoner of War Camps and in the county of L'Arba, Algeria. The anticipated epidemic conditions required for field control demonstrations had not developed in North Africa when the rapid increase of typhus in Naples, Italy, led to a transfer of this part of the program to that city on December 8th, 1943, under the auspices of the Allied Military Government. This epidemic in a non-immune population, well seeded `\irith typhus at the beginning of winter, afforded an unexcelled opportunity for the rapid and dramatic demonstration of I the practical value of the method of delousing without removal of clothing developed in Algeria. The present report covers (1) intensive studies carried out at the Maison-CarrBe Prison near Algiers on the relative efficacy of factory- prepared MYL powder and powders containing DDT preparea with local excipients and applied by various methods ; (2) the extensive field application of insecticide to the general popu.lBtion of the town and county of L'Arba in Algeria, and (3) a rapid field test in a Prisoiier of War Camp, of the new factory prepared U. S. Army - 10% DDT pyrophyllite pow'der. The most important developments of the work in N6rth: Afrih were : (1) the demonstration, on naturally acquired &fe$tations, that both MYL and DDT `are highly efficient pediculicid'es, (2) the development of the air-blown application of louse powder withodt removal of clothing from the body of the person being deloused ; (3) the demonstration that lousy people will take the trouble to come to' accessible delousing stations to get relief f' (4) the deve- lopment of administrative methods for the rapid disinsectization of both military and civilian populations. PERSONNEL ENGAGED IN STUDIES. In Algiers, Dr. Edmund SERGENT, Director of the Pasteur Insti- tute, took a personal interest in the program from the beginning and assigned Dr. BBGUET as the representati,ve of the Pasteur Ins- titute to follow the scientific aspects, .of the. work. Dr. Paul BUCK was assigned from the staff of the Pasteur Institute to work with the Foundation group in the actual application of insecticide and Arch. InsCituC Pasteur d'Alflt%e. LOUSE POWDER STUDIES IN NORTH AFRICA 185 in ascertaining the degree of louse infestation before and after treatment. ~Col. W. S. STONE of the Medical Section of NATOUSA was kept informed of the plans of these studies and was of great assistance in making available needed materials with which to work. Col. STONE .was also instrumental in assigning a number ,of officers from Malaria Units to work in the field application of insecticide at L'Arba. Several of these officers later took an active part in the Naples campaign. Dr. SERGENT was responsible for making arrangements with M. le Directeur de la SBcuritC Generale du Gouvernement Gen6ral for the studies at the Maison-CarrCe Prison and with M. le Prefet du departement d'Alger and the President de la Delegation speciale of L'Arba for the work in that county. All details of t#he work and the observations herewith reported are the direct responsibility of the Rockefeller Foundation Health Commission Typhus Team and Dr. Paul BUCK. MATERIALS Insecticides Initial plans called for the study in North Africa of various newly synthesized insecticides in an attempt to develop a formula better than the MYL of the United States Army. By the time the work began in North Africa, however, the laboratory tests of the new insecticide, DDT, had proceeded far enough to warrant concentrating efforts on field studies o.f MYL and DDT preparations. MYL Insecticidal Powder of the U. S. Army. - The MYL powder tested in the Maison-CarrCe Prison was part of a shipment of powder manufactured by the McCormick Company of Baltimore which had arrived in Algeria in April 1943. This material was packed in 2 ounce shaker tins. The MYL powder used in the field at L'Arba was material ordered early in 1943 from the McCormick Company and packed in specially designed 2 ounce envelopes. The shipment arrived in Algeria in July of the same year. IIDT (2,2-bis (p-ohlorophenyl)-l,l,l-trichloroethane). - When the North African studies began there was available a small lot of 5 pounds of DDT with had been received for field tests from Mr. KNIPLING at the Orlando Laboratory of the U. S. Department of Agriculture. An additional 30 pounds of DDT was received later from the Medical Section NATOUSA, which also furnished the 10% DDT pyropbyllite powder used in the Prisoner of War camps. t. XXIII, n' 3, SeptembTe 1946. 186 F. L. SOPElt, W. A. bAvi8, F. i%. MA#KHhhf, L. A. RlkHL, i'. BUtif Cresylacetate - 2,4. - 2,4 Dinitro Cresylacetate was tested in combination with DDT in a single experiment at Maison-CarrBc. Hair Loticm. - The air lotion used at L'Arba was a modification of that described by DAVIS (I). An emulsion of the active ihgre- dient, phenyl cellosolve, was made in water by the use of a `sodium alkyl sulphate, .Tergitol 07, at a concentration of 0.1 per cent. Since phenyl cellosolve and Tergitol 07 are miscible liquids, a stock emulsion may be prepared and used as required. The emulsion was easily and simply prepared. Five per cent by volume of the stock solution of phenyl cellosolve and .Tergitol 07 was placed in a container of convenient size, such as a one-litre wine bottle. After the proper volume of water had been added and the bottle corked, the mixture was shaken vigorously before application. The suspension separates on standing for several hours but can be quickly re-established by shaking. Diluents for Znsecticide (Barytes, barium sulphate, BaZ%O,). - Barytes is mined at Maison-Carree only a short distance from the prison where tests were carried out. Two samples of this material were received from the Cie cx Produits barytiques Nord-africains %. The sample (Blanc Extra Fin % as found to be sticky but the B: Extra Blanc > proved to be a suitable tine smooth white powder with little or no tendentcy to stickiness. It passed a 200 per inch mesh screen easily and had a pH of 6.8 but was very heavy, being over three times the weight of pyrophyllite used in the preparation of MYL. Cement Dust. - The Societe Lafarge, at Point Pescade, a suburb of Algiers, furnished a finely grouud limestone which is used in the manufacture of cement. Chemical analysis showed this limestone to consist mostly of calcium carbonate with some magnesium car- bonate and oxides of silica, aluminium' and iron. This limestone powder was a dirty gray-brown in color, was gritty to the touch and had a pH of 9.0. It was, however, much lighter than the barytes, weighing approximately the same as does pyrophyllite. Preparation of Insecticides (1) Solvent Method. - Suitable quantities .of DDT concentrate (100%) and the excipient were weighed out. The DDT concentrate was then completely dissolved in a volume of acetone sufficient to yield a w6rkably wet paste when the solution was added `to the excipient. The resulting paste mixture was stirred thoroughly and continuously until the bulk of the acetone had evaporated Ieaving the active ingredient evenly distributed on the excipient. The - (1) DAVIS, W, A., 1943, Journ. Am. Med. Assn ; Vol. 123, p.. &3. Arch. Instttut Pasteur d'Atg&te. LOUSE POWDER STUDIES IN NORTH AFRICA 187 slight amount of acetone remaining evaporated when the mixture was spread in a thin layer on a paper-covered surface for final drying. (2) Mechanical Methds. - A. Hand Mixer : Weighed amounts of the active ingredients and excipients were placed in the baffle chamber of a small hand operated mixer and rotated for specified time intervals. The mixing chamber was fitted with baffleplates and excentrically placed on the surface of a revolving disc so that maximum distribution and mixing of the components could be obtained. When more than one sample was prepared for use in the same experiment the batches were mixed for equal periods of time. B. Bread Mixer : Two batches of 10% DDT powder were pre- pared in a bakery-type bread mixer. The machine consisted of a large cast iron tub which rotated freely in the horizontal axis and an eccentrically places set of mixing paddles which caused the tub to revolve slowly as the paddles moved throu.gb the contents of mixing chamber. From time to time during the mixing period the padd!e action was augmented by manual redistribution of the mate- rials in the tub. DDT cormentrate becomes harmd and lumpy on standing and must be milled shortly before mixing. Since the melting point of DDT is relatively law, the heat generated at the grin,ding surfaces of the mill produces a slight stickiness which prevents a smooth blend with the excipient in a bread mixer. This can `be avoided if a certain amount of excipient be added to the DDT concentrate at the time of milling. Hot table. - When clothing is examined to determine the inci- dence and degree of lousiness, searching the seams becomes a labo- rious task, and any simple means of driving out the lice greatly facilitates their discovery. The louse has a limited adaptation to temperature, and a slight increase of heat causes it to move about and leave the seams. The louse generally crawls upwards and, even though negatively phototropic, will expose itself to light to escape heat applied beneath it. The heat applied must be moderate to avoid stupefaction or even death of the insect. During the early work at the Maison-Carree Prison it was found that effective use could be made of sunlight to heat a black metal surface which served as a < hot table )> on which clothing was exa- mined. Lice present in the clothes emerged from the seams and crawled about the exposed surface of the garments. As the season advanced a kerosene stove was placed below the metal surface with fair results. Later, a cylindrical barrel frame with a superimposed rack for suspending clothing at an angle in the warm current of air rising in the barrel was placed around the kerosene stove. .This arrangement was not entirely satisfactory but proved useful in the final examination of clothing not obviously infested, t. XXIII, n* 5, septembre 4945. 188 F. L. SOPER, W. A. DAVIS, F. S. MARKHAM, L. A. RIEHL, P. BUCK Applicators of Znsecticide Shaker Tins. - Previous experience led to the use of a special type of shaker tin for the application of MYL, which is too moist ond sticky to sift well from the tin in which it is packed. The shaker tins used in North Africa were made by drilling one or two rows of holes in the side wall about the base of a cylindrical tin can having a diameter of three and one-half inches. With the perfora- tions in the side wall (not in the bottom of the tin) it is possible to keep the powder flowing continuously by rotating the tin slightly with each shake. Agriculfural Dusters. - The agricultural dusters used were of two types (trade names, Toxine and Corona) both used by the wine growers in North Africa for the dusting of their vineyards. The Toxine ,duster is a bellows type knapsack duster in which the dust is picked up by an air stream directed downwar,ds on the sur- face of the powder and carried out through an aperture placed near the top of the chamber. The Corona duster is a bellows type knapsack duster in which the powder drops from the hopper into a tube below. The air stream picks up the dust as it passes through the tube. Attempts were made to adapt the Hudson Rotary Powder: Duster No. 608 for the application of MYL powder to clothed individuals, but the physical properties of this powder as well as the mechanical design of the duster rendered its use impractical. Hand Dusters : Hudson, Cadet-Major, Plunger Type. - The powder chamber is immemiately in front of the compression chamber, .for- ming with it a continuous tube with an air valve located in center of partition separating the two chambers. The outlet aperture for dust consists of an axial tube, beginning about one-third of the length of the chamber from its distal end. Powder tends to pack around the outlet tube and discharge as Q slugs ,. The axial inlet and outlet tubes, together with its small capacity cause this duster to be relati- vely inefficient. However, it can be used in an emergency to good advantage, as was demonstrated later in the Naples epidemic. Dobbins < Superbuilt B No. 133. Plunger Type. - Air passes from compression chamber through a tube placed at the circumference of the powder chamber and enters the powder chamber at the distal end. ,Outlet consists of a series of apertures .well back of the distal` end opening into a delivery tube placed diametrically opposite the inlet tube. When the duster is held so that the outlet tube is on the upper side, the air, en route from the inlet to the outlet, must pass upward through the powder carrying some of it into the air space of the powder chamber and thence out through the delivery outlet. This (together with the similar Hudson Admiral Duster No. 765) proved to be a highly satisfactory tool for applying louse powder. 1 Arch. Instlt~t Pasteur &`Algt?rle. LOUSE POWDER STUDIES IN NORTH AFRICA 189 DeVilbiss Hand Power Sprayer Outfit and Modified Dust Guns. For use with portable power compressor units. - The DeVilbiss Sprayer outfit N". TZ-601 is a hand operated unit consisting of a compressor to which is attached a spray gun fitted with a glass or metal container for liquids. The gun was modified to use positive rather than negative pressure, but was found to be unsatisfactory because of the continued demand for high pressure required for its operation. The modified De Vilbiss sprayer gun and several others built through the cooperation of the Surgeon's Office NATOUSA and the U. S. Army Air `Corps shops were used with varyin,g degrees of success when attached to gasoline driven air compressor units. In general the limitations of this type of equipment are : (a) the ability of the compressor unit to maintain sufficient pressure to operate two or more guns continuously ; (b) the ability of the powder chamber to withstand the abrasive action of the excipient dust ; (c) the faci- lity with which the powder chamber can be refilled and (d) the need for mechanically trained operators to care for the equipment. METHODS Determination of louse infestation The degree of louse infestation was dktermined with varying degrees of thoroughness. In work at the Maison-Carrke Prison the degree of lousiness of each individual'was determined by removing all of the clothing and carefully examining the inner surfaces and seams f0.r lice. In preliminary survey work, when an incomplete search revealed the presence of ten or more lice, the individual was registered at 10 (I) plus. In post-treatment examinations all garments were examined and complete counts made. The examinations were generally made in bright sunlight and negative garments were often subjected to hottable treatment to aid in the discovery in insects. The classification of post-treatment of lice as to stage of develop- ment was found to be very useful in evaluating the insecticide tested. Each insect was recorded as newly hatched, immature or adult. The post-treatment finding of only newly hatched lice indicates that the insecticide, although not ovicidal, has a persistent action which destroys the instars before they reach the nymphal or adult (1) Previous experience in community surveys had shown that popIa- tions can be roughly divided into two groups ; those having not over 9 lice and those havineg 10 or more. iMost of the persons fal'ling in the first gronp will be found to have not more than' 5 lice. t. XXJII, n* S, seplembre 1945. 190 F. L. SOPER, WY, A. DAVIS, F. S. MARKHAM, L. A. RIEHL, P. BUCK . stages. The finding of immature forms on treated garments is not necessarily an indication for repeated treatment. At L'Arba the subjects were not disrobed to determine the degree of louse infestation. A Iouse-index based on a rapid examination of the clothing about the collar and over the shoulders was considered sufficient for the purpose of this study. At Maison-Car&e Prison all examinations were carried out by members of the Rockefeller Foundation Typhus Team or Dr. BUCK, with a few specially trained prisoners working under their direct supervision. Application of Powder Shaker Tin. - If bedding is to be treated the blankets are Arst spread out flat on the floor or table top and lightly dusted with powder from the shaker tin. The blanket -is then folded once-over. Next, the upper garments after having been turned inside-out are laid one by one in the center of the folded blanket and dusted indi- vidually. Particular care is taken to ensure thorough pow,dering of the neckband, and the seams about the shoulders, arms and waist. Coats, shirts and under-shirts are treated alike. The lower garments after being turned inside-out are treated in the same fashion. The side-seams of the trousers and the seams about the waistband, seat and crotch of both the trousers and underwear are heavily pow- dered. A certain amount of powder can be worked under ,the overlapping seams of the trousers by a brisk back and forth bru- shing movement over the surface of the garment. The inside of the hat or cap is then powdered and added to the pile in the center of the blanket. Finally the corners of the blanket are folded over the dusted clothing so as to form a closed bundle which is given several smart blows at the sides and top in order to fluff the powder throughout the treated garments and blanket. If blankets are not being treated, the overcoat or waistcoat may be used as the covering of the bundle of clotIKng in the final step. Mechanical Dust Pumps. - Essentially the same technique is employed in applying powder with both the hand operated and the powder-driven compressed air dust pumps. The following paragraphs are quoted from the directions for powdering prepared 2 November, 1943: I( Powdering Pechnique M 11 In using the duster, the operator should remember that powder should be distributed on the inner surfaces of the inner garments an,d on the skin itself. Those doing the work for the first time should. have the clothing removed from the first persons powdered to observe the `results obtained. If properly done, the entire inner garments should be more or Arch. Jnstltut Pasteur &`Alg&te. LOUSE POWDER STUDIES IN NORTH AFRICA 1% less completely covered with powder and there should be visible p.owder on the `body hairs of the chest, back, thighs, armpit,s. and of the pubic and perineal regions. Since body lice are most often found in the seams of the clothes about the neck, armpits, waist, shirt-tail and crotch of the pants, these areas are particularly important ones! to be powd'ered. (I The hand duster a l-liter bottle containing a 5% emulsion of phenyl cellosolve lotion for treatment of heads, and a supply of absorbent tissues to protect the eyes of the subject ,during the treatment of his head. Each team began work at a different designated point on the map. Arab houses are built around a central uncovered court and because the light was usually better and the space greater than in the rooms, most of the treatments were given in the courtyards. The number of the families in the court was determined ; names and ages of the members of each family were listed on the indivi- dual record form under the father's name. The name of the wife followed that of the husband ; the children were listed in order of their age. If there was more than one wife, children were liste'd under the mother's name. After completion of the familly census the treatment of individuals began. Usually in each household a child of 8-12 years was selected as the first individual to be deloused. The chiIdren regarded it as a game and were perfectly willing to submit to powdering. The Arch. Znstitut Pasteur d'dlgt?rfe. LOUSE POWDER STUDIES IN NORTH AFRICA 207 response of t'hese children )g,enerally remo,ved the hesitancy of older and younger members of the family. Before application of powder, the collar, shoulder yoke and armpits of the upper garments were examined for lice. The pre- sence of either lice or viable eggs was used as an index of lousiness. Lousiness was recorded as zero, slight or heavy. Treatment of the subject began with the application of powder to the clothing. With the exception .of the treatment of the head, the procedure used in applying powder to the clothing was that outlined previously. When pow,dering of the clothing had been completed the person was seated, and the hair treated with phenyl-cellosolve lotion. The individual was given a piece of absorbent tissue and instructed to hold it in pl'ace against the forehead and over the eyes. Lotion was shaken from the bottle into the hair and rubbed in by hand until fhe hair was thoroughly wetted. The piece of absorbent tissue was then used to wipe the forehead an,d hair to prevent lotion from reaching the eyes. When treatment of all residents present in the house had been finished, the team moved to the adjoining house and so on until their section of the lotissement had been finished. First treatments in lotissement Rugeaud were completed on Octo- ber 14th. The second application started an October 18th and was carried out by a single team consisting of one doctor, a French nurse and the Arab girl. This second series of treatments was finished on October 25th. Results obtained are presented in Table VI: TABLE VI Total inhabitants 680 Refasals Persons not treated --I No. 010 -- 60 8.8 PSEKIOS Psrsons treated treated "Ill33 twice --- WC-- No. "lo No. % ---- 620 9i.9 Wb i 6F.8 The work in L'Arba was interrupted by the invitation of the Surgeon's Office NATOUSA to conduct a delousing demonstration in Prisoner of War camps. As personnel again became available to continue the program in L'Arba, a survey of the initial experience in lotissement Bugeaud showed that : (i) Arab men are not able to enter houses other than those of their immediate families and are of little use in house to house work ; (2) treatment of Arab women and female children woul'd have to be done entirely by doctors, nurses or women workers ; (3) Arabs were willing to accept treat- ment (only 1.7 % of the inhabitants of lotissement Bugeaud refused to be treated) and (4) Arabs expressed their appreciation at being t. XXIII, no 3, septembre i945. 208 F. L. SOPER. Vi. A. D$VIS, F. S. NARKHAM, L. A. RIEHL, P. BUCK freed of lice, fleas and other body-infesting insects. While the difficulty of obtaining employees for delousing Arab women remai- ned a problem of considerable importance, the willingness of the Arabs to accept delousing measures and their desire for additional work in the community encouraged the consideration of a larger program in the area. EXPANSION OF PROGRAM IN L'ARB~ COMMUNE On November Znd, the mayor of L'Arba and Monsieur Mohied- dine, grandson of the Caid, were consulted regarding the expansion of the delousing program. Since the men from the douars or moun- tain districts came in to L'Arba at least once a week to trade they would be a constant source of rkinfestation for the villagers if they and their families were unpowdered. This would mean the treat- ment of approximately 10.000 additional persons, but it offered an opportunity to gain valuable experience. Moreover lousiness in the douars was universal and typhus frequently made its first appear- ance in these areas. If delousing measures were to be undertaken in the douars, the people living on the farms should also be included. It was decided therefore to accept the limits of the commune (county) of L'Arba as the boundaries for the delousing program. This area encom- passed the town of L'Arba with a population of some 1500 Euro- peans and 3500 Arabs, the 6 mountain douars with roughly 8000 inhabitants and approximately 100 Europeans and 1900 Arabs living on the various farms on the plain north of the town. The primary obstacle to the execution of the enlarged program was the non-availability of female assistants. For a variety of reasons connected with the war, full employment of the menfolk, local, social and racial prejudices, inability to transport and feed imported per- sonnel, etc., the bulk of tEe work would have to be done with a very limited amount of assistance. The entire project was ultima- tely carried out by two staff supervisors, two public health nurses and a 15 year old Arab girl to, powder the Arabe women. They were aided from time to time by the leader of the local Girl Scout orga- nization, two of her friends and some of their young charges work- ing on a voluntary basis. A central base of operations was established in a combination garage-stable located in the first floor of a dwelling house. This was the most suitable site available and it served as headquarters, powdering station and supply depot. Three of the staff found living accommodation with the family occupying the house. Jn spite of these unimpressive facilities and the nature of the problem being attacked as well as the doubts expressed by early advisors, the project was wel! received and won the active coope- ration of the local religious, educational, political and medical leadership. Arch. ZnstUut FWSteuT d'Algt?Tle. LOUSE POWDER %TUblES IN NORTH AFRICA 209 Villuge house-to-house dusting. - It was decided to start the delousing work in L'Arba in the seciion of the town known as Lotis- sement Eglise. The mayor and the reprcscntative of the Caid felt that the Arabs would be more receptive to the program if house to house work was used in the beginning as had been done in Lotis- sement Bugeautl. In accordance with their wishes the work in Lotis- sement Eglise was planned on this basis. In general the sections of the town in which the Arabs live do not have named streets and nnmberctl houses. Since it was desired to have a record of the location of treated and untreated families and individuals, the first step was the drafting of a map. A rough sketch map was considered sufficient for the purpose of locating individual families and for assigning work to the census and delou- sing teams. The limits of the lotissements of L'Arba are quite defi- nite and are generally known by the residents of the town ; this greatly facilitated mapping. Several copies of the map were then made, so that one could be supplied to each of the powdering teams. The lotissement was divided into three approximately equal areas. The work assignment for a given delousing team was indicated on the map supplied it. Teams were directed to begin at the lowest number and work the families in order. The powdering teams for Lotisscment Eglise were made up of three females each ; one rccordcd the census of the family while the two others applied the insecticide. MYL was used on both the head and clothing in treating Lotis- sement Eglise, since the liquid pediculicide for the head required extra equipment and material. The women offered no objection to having their heads powrered. Temporary Powdering Stations in L'Arba Villa{ge. - House-to- house work as conducted in the Lotisscmcnt Eglise gave a relatively high percentage of coverage (91.8) but the number of treatments per man hour of work was low. Inquiries showed that a fair pro- portion of the inhabitants of Lotissemcnt Djipoulon were .willin,g to come to the djama or community house to be dusted. The area was therefore mapped and censuscd and the people notified when to present themselves at the djama for powdering. As they appeared and were treated they were checked OK on the census lists. This system resulted in an increase in the number of persons treated per man hour of work. A further modification in the plan of operations was made in Lotissement Medjabri because it had been found in Djipoulou that valuable working time was lost in checking the census lists to locate the names of applicants for treatment. In order to overcome this difficulty when the census of Lotisscment Medjabri was made each family was given a numbered ticket which was to be presented t. XXIII, no 3, septembre 1945. 210 F. L. SOPER, w. A. DAVIS, F. s. MARKHAM, I,. A. RIEHL, P. BUCK when it appeared at the powdering station. This proved to be satisfactory and effected a further saving in time per treatment. In those lotissements which had no djama or community house, the cooperation of influential residents of the area was enlisted and temporary powdering station were set up in the courtyards or other convenient places in the residences of private citizens. Some- times only the women and girls were dusted at these stations while the men and boys were asked to go to the central powdering station to be treated. These various schemes of operation at temporary powdering sta- tions in the lotissements were combined with a program of Q; clean- up D work so as to reach those who had failed for one reason or another to present themselves at the temporary treatment centers. A small squad armed with the census list called at the home of each family that had been missed according to the checked census record. As a rule the girls and women reached in their homes during the daytime by the follow-up squad. The men and boys were acco- modated at a temporary station which operated at a set time after working honrs in the early evening. This type of follow-up dusting helped greatly to maintain the relatively high percent of coverage obtained in the L'Arba lotissements. Temporary Powdering Slations in the Commune outside the Village of L'Arba. The delousing program in the douars or mountain districts outside the village of L'Arba was arranged through the cooperation of the Mayor and the Chefs de Fractions, or district leaders. Mapping and census of these outlying regions was not practical due to the scattered nature of the population and the difficulties of communi- cation. The Chef de Fraction therefore assumed the responsability of having the inhabitants of his districts at a convenient and suit- able point in the douar for powdering at a designated time. Names were listed as the people were dusted and separate facilities were provided for the treatment of males and females. Estimates of the coverage in the douars were made by checking the lists of persons treated against the number of ration cards issued for the district. The farms in the L'Arba plain were handled as individual units. Arrangements were made with the owner as to a suitable time and place for the dusting. He prepared lists of his employees and their families for use by the powdering squads. The men were usually treated at some central point on the farm while the women and children were dusted at the < gourhis B or family dwelling places. Permanent Cenfral Powdering Station. The name, age, sex and address of those coming to the permanent powdering station were recorded. Checking these lists presented Arch. Znstltut PasteZtT d'A@t?rle. LOUSE I'OWDER STUDIES IN R'OKTB AFRICA 211 many difficulties but insofar as possible the individuals who came to the station were crcdiled to the lotissrments, douars or other sub- divisions mherc they resided. This detail was somewhat simplified after the introduction of numbered tickets. The station was kept open until 7 PM., every day and the bulk of its patrons were older men, youths and children ; women seldom came. in addition to the central powdering station a certain amount of dusting was done in the mnrkct,place on Wednesdays and Sundays, the local market days. TIccords of this work were kept and treated in the same manner as those at the central station. Insiitutional Delousing. Early in the L'Arba program arrangements were made with the local school authorities for the dciousiu, 0~ of the school children in their class rooms. The efYcctivencss of the treatment would thus be demonstrated in homes throughout the community and it was hoped that this would facilitate the general acceptance of the program by the adults. With the assistance cf the directors and teachers the work was carried out in both the boy's and girl's schools. The only differ- ence in hzndling of the two groups brin, `7 the application of the hair lotion to the hair of the girls. Most of the boys wore their hair very short al?tt it was easier to treat them with powder than with lotion. Records were kept of the names ant1 addresses ant the incidence of lollsiness among the pupils. hXUSSION OF RESULTS. During the course of the dc!ousing project in L'Arba 9,376, or 66.8% of the 14,030 Arab inhabitants of the commune were pow- tlered. There were 4.241, or 30.2'%, dusted twice and 4,671, or 33.2%, were not treated. Tables VII and VlII show the number of percent of first and second treatments and the number of persons treated per man hour of labor. Table IX presents a comparaison of results in house-to-house con- tacts and the use of temporary powdering points. The breakdown of powdered individuals into sex and age groups is given in Tables X and XI. Personnel. - The primary problem of the L'Arba program was the shortage of fcm:~lc assistants to work with Arab women. It is ;mprnrtical to attempt large scale tlPlousing in the region relying only on professional personnel such as doctors ant! nurses to powder 6hr Arab women. With the greatly inflated family incomes t. XX,ZIZ, n' 9, septembre 1945. 212 F. L. SOPER, IV. A. DAVIS, F. S. MARKHAM, I,. A. RIEHL, P. BUCK TABLE VII. - FIRST AND SECOND -. Persons Location not powdered Number Percent Lotissement Egllse.. . :. . . . . . Lotissernent Djipouloo.. . Lotissemeut LVedjabri.. . . . . . . . Lotisoemsnt El FRG~.. . . . . . . . . Lolissement .\loll.. . . . . Lotissement lloulevard de France.. Lotissement Due d Aumale. . . . . . . . Lolissemaot Roolevard,Lamartine... . . . Lotissement Rue Carnot.. . Lotissement Rue Blandan . . . . . $93 2b 8.2 452 32 7.0 522 66 42.6 sob 100 13.4 365 53 lb.5 bil 69 ib.6 SO9 63 20.6 101 22 24.8 77 5 6.b 907 * 37 47.9 TOTAL for Lotissements. ., ._.. _. 3.601 b51 is.9 Eeole da Gaqoos.. . . b07 7 4.7 Ecole Primaire de Filles.. . . . . . 234 b 1.7 Civil Prison.. . , . . . so 0 0 Powdering Station . . ._.... -- --~ GRAND TOTAL., . _, t. 4.462 b62 il.4 -- Census made by deloosiog personnel as part of the work of the delousing program. Arch lnstltut Pasteur d'Algt?rle I>OUSE POWDER STUDlES IN NORTH AFRICA 213 TREATMESTS IN L'ARBA VILLAGE. _- Persons Persons I't?rSOnS Total Total powdered powdered twice treated number number -- -I- per man treatments man hours Kumber Percent Number Percent hour 269 91.8 198 67.6 465 88 5.3 420 93.0 286 63.3 i96 112 6.3 b56 87.k 340 65.1 796 9s 8.3 iOb 87.6 &2h 5t.i 1.128 176 6.6 312 85.5 1% 41.9 b65 86 5b 402 i ::: s-2 i 47.6 626 88 i.1 166 fi9 33.0 235 32 7.3 79 78.2 30 S9.i 409 6 1A.i 72 93.6 3.7 bS.8 105 40 10.5 170 81.4 ib 35.7 2b4 ib 47.4 -~ 3.050 87 1 1.831 52 3 4.881 io7 6.9 400 98.3 353 86.7 753 74 10.2 230 99.3 149 63.7 379 41 9.2 PO 100 13 100' 33 4 x.3 411** 418'* 88 4.8 --- 3.700 X8 9 2 3b6 56.`1 6.016 9Ib 6.6 -- * Other plisoners bad been released during interval between treatments. ** Treated at L'Arba powdering stati6n. but assigned and counted in individual lotissemeots. t. XXIII, no S, septembre 1945. 214 F. L. SOPER, W. A. DAVIS, F. S. MARKHAM, L. A. RIEHL, P. BUCK TABLE VIII. - FIRST AND SECOND Location Censos not powdered Number Percent Douar Teooot ............................... 166 * 0 0 Douar Sakamody .............................. 450 o ? ? ? Daoar Zerboul... .............................. 1.186 o * 306 25.8 Douar Bousequine ............................. 1.435 o ? ??? 34.5 Dollar S011a11e ................................ ????? o ? 791 64.5 Douar Khodja and Bakir ....................... 3.125 o ? 2 5*0 80.5 Powdering station .......................... -- TOTAL for Dooms ................... 7.640 4.110 537 ,Mobieddine District *** ........................... Bohane District.. *** .............................. Powdering Station ........................... Farm Saint0 Aogi?le ........................... 55 * 0 0 Farm El Taous .............................. 126 * 25 19.8 Farm Grandou ............................... 138 o ? ? Farm Ben Assen ............................... 279 * 24 8.6 Farm Cooderc ................................. 5' 0 0 Farm Claret .................................. 37 * 0 0 Farm Tordjmaun ............................. 97 o ? ? Farm Vallot .................................. 31 o ? ? Farm Vidal............ ...................... ?? o ? ? Farm Boochtop ................................. 35 o ? ? Farm Balgodene ................................ 26 o ? ? Farm El Euldj.. ............................ 38 o ? ? ? Farm Valero ................................... 12 * 0 0 Farm Saint Philippe .......................... 61 * 0 0 Farm Lagae .................................. 13 o ? ? Farm Ben Nouar el Looz ................... 166 * 0 0 Farm Mohieddine. ......................... 84 * 0 0 Farm Kadem .................................. 27' 1 3.7 Farm Mokhfi.. .............................. 296 ' 0 0 Farm Sarraooi.. ............................. 31 o ? ? Farm Cherabas ............................. 153 o ? ? Farm Cberagas .............................. 55 * 0 0 Farm Racbdi ................................ 55 * 0 0 Farm Bealaoudi .......................... 69 * 0 0 Powdering Station.. ....................... TOTAL for Farms ................... 1.914 50 2.6 GRAND TOTAL.. .................. 9.849 4.160 42.2 - tien~us XaKen DY tne powaerlng team at Ihe time Of tl?eatment. - *' Census according to the ratlon cards supplied by the Office of the Mayor, L'Arba. - o ** Complete census not available. - o ' Due to weather conditions and impassa- Arch. Imtdtut F!aSteUr d'Algt?rte. LOUSE POWDER STUDIES IN NORTH AFRICA 215 TREATMENTS OUTSIDE L'ARBA VILLAGE. Persons powdered I I I I POW, Persons Persons Persons Total Total powdered powdered twice treated "umber number --e. ~--vv per man Number Percent Sumber Percent trealnlents man hours hour (66 (66 100 100 71 71 1 42.8 42.8 1 23i 23i 1 63 63 1, 38 467 467 100 100 25% 25% 50.0 719 75 9.6 880 74 3 f74 14.4 1.051 113 9.3 940 65 5 83 5.9 I.025 112 9.2 496 38.5 121 94 617 76 8.1 607 19.5 95 3.0 iOP II3 6.2 287 *" 287 60 4.8 __-- ..- --~ 3.556 46.3 i95 to.3 4.351 612 7.1 104 90 194 47 4.1 182 ss 2io `34 41.3 13 I" i2"' 3 `r.0 55 400 55 100 410 101 80.2 b1 31.5 l&2 138 100 95 68.8 233 355 19.4 147 52.6 402 5 100 *, 5 37 100 28 75.7 65 91 100 81 83.5 17x 31 loo 29 93.5 UJ 45 100 20 80.0 45 35 100 27 77.1 62 26 100 12 46.2 38 38 100 29 76.3 67 i2 100 6 ) 33.3 16 61 100 52 85.2 113 i3 100 i3 400.0 21; 166 100 58 34.9 824 84 100 53 63.1 137 26 96.3 ii 40.7 37 296 100 205 69.3 501 31 I00 23 74.2 5% 953 100 .I 153 55 100 tl 55 55 400 L' 55 69 100 69 166*" 166 * ' 35 4.8 ____ -___ -__-- ___- ---~~~ __- 1.864 97.4 983 51.4 4.847 WI G.4 5.706 57.8 I.956 19.8 7.662 1.18G 6.6 bilitg of roads no visit made for second treatment. - o " Treated at L'Arba powdering station, but avipned and counted in individual douar (farm) totals t. XXIII, nQ S, septembre 1945. 216 F. L. SOPER, W. A. DAVIS, F. S. MARKHAM, L. A. RIEHL, P. BUCK -___ Arch. Instltut PaSttW d'Alu&le. LOUSE POWDER STUDIES IN NORTH AFRICA 217 of war time Arabe women are not willing to work outside their homes. With the return of peace and the easing of transportation and food problems it may be practical to import female assistants from the urban centers where some Europeans and less orthodox Arab women are to be found. On the other hand, if a community were actually confronted with epidemic typhus, local leadership would probably become more etfective in solving this problem. TABLE X: DISTRIBUTION 0~ TRR.~TED IiYDIVIDUALS BY sIci AND AGE GROUPS AMONG THE ARAB INHABITANTS OF L'ARBA VILLAGE. Age qronp No. of Untreated Treated Powdered twice in*ivi. - _I-.- c - ^ - . .-~- J- duals No. "IQ No. ; "/r, No. O/o --11---m .Men over 16.. _. . i.03 369 34.5 702 65.5 206 49.2 Boys T&16........ 948 54 5.i 894 94.3 563 59.b Women over 16.. 4.079 56 5.2 i.022 Yb.8 711 * 6i.9 ~~~- ___ - Girls 2-16.. 808 ?b 2.9 784 97.i 613 75.9 .- Infants O-t.. . . . . 275 8 2.9 267 97.1 192 6!) 8 Problems of Community Delousing. - The favorable reception of the delousing treatment by the citizens of L'Arba is better indicated by the low percentage of refusals (1.7% Table VI), than by the per- centage of over-all coverage in the community as a whole. The obvious effectiveness of the anti-louse powder and the personal convenience and ease of applying it without removal of the cloth- ing were primarily responsible for the results attained. Racial discrimination, a question which was raised during the formative phase of the program, never became a problem because the European, both at school and in the home, accepted the treatment without protest. Aside from the personnel difficulties already mentioned, the major problem of the project was administrative : What practical method would reach the greatest number of people ? The treatment was acceptable, but experience showed that it was not as actively sought for as might be expected in such a generally infested popu- lation. The character of the response may perhaps be explained in large part by two tactors : the almost Oriental indifference of the Arab born of long association to the discomfort and danger con- nected witfi blood-sucking ectoparasites, freedom from which the majority of the people have seldom or never known, and the multi- tude of proscriptions that so completely hedge and limit the acti- vities of Arab women. t. XXIII, n" S. septembre 1945. 218 F. L. SOPER, W. A. DAVIS, F. S. MARKHAM, L. A. RIEHL, P. BUCK By far the simplest admini,strative pr,o,cedure is to set up a central powdering station and invite the people to come to it for treatment. But during the month of its operation the central powdering station in L'Arha was ufilized by only 10% of the village inhabitants as compared to 8.7% of the farm dtvellers and 3.9% of those living in the douars. Moreover, 92.7% of the patrons at the central sta- tion and 95.8% of those treated at the market place in L'Arba were males (Table XI). It is very probable that had other de1ousin.g work been going on simultaneously in the lotissements the response at the central station would have been much greater. Nevertheless, it is evident that this system would fail to reach most of the females and very young males. It appears, therefore, that the treatment must be made more convenient by bringing the facilities closer to the home and establishing rather direct contact with the people as was done by the house-to-house work and the use of temporary powdering stations in the lotissements, farms and douars. TABLE XI. - SEX AND AGE DISTRIBUTION OF TREATMENTS IN THE DOUARS AT THE POWDERING STATION AND IN THE MARKET PLXE OF L'ARBA. Location I Number and Percent of Various Age Groups Treated Total LMales 16 + treat- ---. ments No. /o .-e- Tenout.. 166 Sakamody.. 467 Zerboot.. . . 880 Boosequine. 940 Sohane.. . 496 Kodja and Bakir.. . 607 Districts rllohieddine. 403 Bohane...... 482 TOTAL.. 3.813 powdering Station. 667 Market Place 216 -- TOTAL.. . 883 I Females I Lvales I Females Infants 16 + 2-16 2-16 I) 2 --- - - -*-- NO O/o NO "lo NO. O/o LX0 "i. -- ,-- 36 24.i 39 133 28.5 91 180 20.5 230 487 i9.9 233 429 26.0 12i 220 36.2 95 16 13.3 30 34 46.7 66 933 24.3 691 --m 486 i2 9 b 4bF 67 G I 632 7t.6 6 23 5 49.5 26.4 P4.8 25 6 28.6 25 3 -~ 23 2 62 25.3 423 26.3 214 23.9 223 23.7 419 23.9 4i3 28.5 432 19.8 64 28.2 ~__ 36 20.5 45 9.0 to5 22.5 45 3.2 207 23.6 $2 5 `9 237 25.2 GO F.6 108 21.9 13 2.G 94 45.5 25 6.1 18 171 7 6.7 42 23.1 18 9.8 815 24 9 203 5.6 -m-,- Arch. Znstdtut Pasteur d'Algt?rle. LOUSE I'OM'UER STUDIES IN NORTH AFRICA 219 Considering the distance involved and the difficulties of commu- nication the response in the douars is worthy of comment. Many of the people in these mountain districts travelled on foot for several hours to reach the wayside powdering station in the hills. In two of the six tlouars all of the inhabitants came in for the first treatment while in two others between 6.7 and 75% of the residents were dusted. In the remaining two, Khodja and Bakir, which were the largest and the ones t'hcrefore where travel and communication the most difficult, the response was poor. They brought the over-all percentage for all the dounrs down to 46.3. This figure is to be compared with 87.1% coverage in the lotissements of L'Arba village, where pre-census and house-to-house clean-up work established direct contact with the greater part of the population. In the douars explanation of the program and notification of the time and place of the dusting was the sole responsibi!ity of the Chefs de Fractions and the success of the work there was determined by the extent of their cooperation. Unlike the people in the village those in the douars had not the benefit of a convincing preliminary demonstration such as that in Lotissement Bugeaud, which greatly facilitated the work in the other lotissements of L'hrba. In the village of L'Arba itself where 87.1% of the population was dusted, 72.2%. (Table X) of the untreated group were males over 16 years of age. Of the ad!ult males only 65.5 %j were dusted, whereas 94% of the rest of the population were powdered. Most of the adult males were employed, many of them on night shifts, in the military installations and depots in the area and it is believed that absence from home and personal inconvenience rather than a reluc- tance to be treated accounts for the high proportion of untreated males over 16 years of age. This interpretation is supported by the fact that in the douars where the men were engaged in the fields the proportion of treated and untreated adult males was about the same as that observed in the other population categories (Table XI). While the reaction to different administrative methods varied from one part of the community to another it is believed that in normal times a sustained delousing program would meet with a very favorable response in a population familiar with its benefits. Second Trenfments. - A single treatment gave prompt relief from the discomforts of being lousy, whi'ch persisted beyond the date set for retreatment. The result was that the people could not be convinced of the need of exerting themselves to seek a second treat- ment so soon. In the douars where the most effort was required to get treatment, only 10.3% of the inhabitants presented themselves for the second powdering (Table WIT). In the village of L'Arba where relatively little effort was involved, only 52.3% were treated a second time (Table VII). The smallest percentage of second treat- t. Xx,111, n' 5, septembre 1945. 220 F. L. SOPER, 1%`. A. DAVIS, F. S. MARKHAM, L. A. RIEHL, P. BUCK ments was among adult males, again the group that would have to exert itself the most to be re-treated. Costs of the L'Arba Dekwsing Project. - The figures listed are based only on necessary expenditures for insecticides, payroll, trans- portation and storage ; staff salaries are not included : Total expenditures . . . . . . . . . . . $ 1580.10 Total people treated (once) . . . . . 9406 cost per person . . . . . . . . . . . . . . . . 16.8 Tota'l number treatments given.. . . . . 13,708 Cost per treatment . . . . . . . . . . . 11.5 `Cost of insecticide per treatment . . . . 6.5 Cost of labor per treatment . . . . . . 1.6 Cost of transportation par treatment 2.5 The high cost of the insecticide was largely due to the fact that it was packaged in specially designed shaker envelopes which had to be hand filled. The use of the hand dust pump made the special envelopes unnecessary but the production costs were included in the purchase price of the insecticide. Bulk powder is preferable for use in dust pumps and much less expensive. Transport charges were inordinately high due to the scarcity of vehicles and the market price of fuel. Much of the work in the dounrs and farms was done with a truck hired at the rate of $ 20 per day. In normal peacetime the cost per treatment would probably be reduced to about one third that of the experimental program. Treatments per Man-hour. - Tables VII, VIII and IX include data on the number of persons treated per man-hour of work in the village, the douars, farms and institutions. Man-hours are calculated on the basis of the total number of hours for which the workers were paid-not the actual time spent in dusting, census-taking etc. The time spent going to and from a given place of work is included in the man-hours charged against each farm, douar, or lotissement. In the lotissements of the village the time spent in travel was slight, whereas it represents a very considerable part of the man-hours charged against the work in the douars. In smaTl units such as lotissements Lamartine, Carnot and Blandan the women and girls were done by a single worker going from house to house while the men and boys were done at the central station. The result in these small units is an appearance of greater efficiency when compared with the larger units where several crews were at work. Control of Lice. - Among the working class people and farmers of the L'Arba commune lousiness was almost universal. Indirect qualitative evidence of the success of the iork was not lacking. Those who came for a second treatment frequently expressed their delight at being able to sleep undisturbed by lice, many of them for the first time since they could remember. Oftentimes workers were offered two to four eggs, worth 25 or 30 cents each, in exchange for Arch lnstltut Pasteur d'Alg&le LOUSE I'OWDER STUDIES IN NORTH AFRICA 221 a packet of powder. One or two enterprising young workers had to be discharged when it was discovered that they had stolen enve- lopes of powder and sold them at stiff black market prices as high as `i0 cents each. Since there is little conceivable misuse to which the powder could be put these incidents indicate that the value of the insecticide was thoroughly appreciated and suggest that were it possible to market the powder through normal commercial chan- nels the community might do much for itself in suppressing lousiness. Control of Typhus. - There was no opportunity to determine the effectiveness of the delousing at L'Arba in the control of typhus. While typhus had been present in the area during the two previous winters, no cases were reported during the time the work was in progress nor were casts of typhus reported in neighboring com- munes. The opportunity of collecting data on the prevalence of typhus was lost by the transfer of Rockefeller Foundation person- nel to Italy to organize the campaign against typhus in Naples early in December, 1943. SECTION III : PRISONER OF WAR CAMP DEMONSTRATIONS (Field Test of 1070 DDT-Pyrophyllite Powder) The experiments in the Maison-Carrke prison and the preliminary field test at L'Arba amply showed the practical nature of the method of applying insecticide to infested individuals without remov- iug their clothing. Recognising the advantage of this technique in the handling of prisoners of war, the Surgeon's Office NATOUSA invited the Rorkcfeller Foundation Typhus Team to stage a series of demonstrations in the Mediterranean area. The invitation was accepted and arrangements were made for demonstrations in Alge- ria: Morocco, Tunis and Sicily during October and November. A small stock of the U.S. -4rmy's recently adopted 10% DDT- pyrophyllitc louSe powder was available and it was decided to field test this new preparation in one of the Prisoner of War (POW) camps where demonstrations were to hc held. The following is :I brief summary of the conditions under which the test was carried out and the results observed. The work was done with the full co- operation ot' the Base Section Surgeon, the commanding officer of the POW camp and with the assistance of U.S. Army Sanitary Corps Xalaria Control Units in the area. A stockade made to hold approximately 1500 prisoners at one of the Algerian POW' scamps was selected and work was started on 18 October, 1943. The commanding officer agreed not to add new prisoners to the stockade after the powdering bad been done, but did make some withdrawals during the period of observation. t. XXIII, no 3, septembre 19$5. 222 F. I,. SOPER, W. A. DAVIS, F. S. MARKHAM, L. A. RIEHL, P. BUCK The prisoners lived in pyramidal tents which were numbered individually and by row. Tents in various parts of the stockade were chosen at random and their occupants thoroughly searched for lice. Using the technique previously described, the examina- tions were made under the supervision of the Typhus Team by 12 enlisted men of the Sanitary Corps under the command of Lt. J. F. STALLWORTH. Records were kept of the name and location of each man examined and of the number and developmental stages of the lice discovered. The clothing of 252 prisoners was examined and 193 (77%) were found to be infested. Of the 193 men 75 (30%) had ten or more lice. The application of powder with Dobbins < Superbuilt * No. 133 hand dusters began on October 19th and was completed the follow- ing morning. It is of interest to note that although the enlisted men of the Sanitary Corps started the dusting of the prisoners, within a short time they had the prisoners themselves doing the dusting under their supervision. All of the garments worn by the prisoners together with extra clothing and blankets were powdered. Retwecn 1300 and 1400 prisoners were dusted. On November 4th, after a lapse of 16 days, two of the Typhus Team returned to the POW camp to supervise the follow-up exami- nation and to observe the effectiveness of this first field test of 10% DDT louse powder. The examinations were made by the same personnel as before. Of the 252 prisoners whose garments had been searched previously, 152 were still in the stockage. The examina- tion of the clothing of 151 of these men failed to disclose lice. On the 152nd man 8 nymphal and 2 adult lice were found. Upon questioning, this man said that he had been admitted to the hospital on the evening of the preliminary examination and that he had returned to the stockage after the dusting crews had. finished on October 21st and thus had escaped being dusted. His statements were confirmed by an inspection of the Infirmary records. It was concluded from these observations that, (1) the technique of applying insecticidal powder without removal of the clothing was a thoroughly practical procedure, even when carried out by unskilled personnel and that (2) the 10 % DDT-pyrophyllite powder is a highly effective preparation. Other demonstration were held in Morocco on October 22nd, in Tunis on November 12th and in Sicily on November 16th. SUMMARY Field work to test the efficiency of louse powders on naturally infested population groups and to develop methods for the rapid application of louse powders was carried out in North Africa dur- ing the second half of 1943. The powders tested were MYL and Arch. Znstltut Pasteur d'Alg&ie. LOUSE POWDER STUDIES IN NORTH AFRICA 223 various combinations of DDT. Observations were carried out in a civilian prison, in a rural county with both European and Arab populations and in prisoner-of-war camps. Administrative tech- niques tested included, (1) House-to-house block dusting (2) Delous- ing stations (3) Local temporary delousing stations open only for a day at a previously notified time and place (4) Farm-to-farm delousing (5) Institutional delousing. In the early tests in North Africa, the powder was dusted by hand from shaker tins to the inner surfaces of garments which had been removed from the wearers. In August, the first demonstration was made of the possibility of satisfactorily powdering the ,rlothing without removal from the body. This was followed by tests of various types of hand and power operated dusting equipment. CONCLUSIONS 1. In a closed population group where everyone is treated and the group protected from reinfestation from untreated groups, two treatments of either MYL or DDT at an interval of a fortnight may be expected to reduce lousiness immediately and prevent a dan- gerous degree of infestation d,dring a 3 month period. I.ouse eradi- cation in such a closed population should be possible with a few additional treatments. 2. Individuals, living, working and sleeping, in close contact with heavily infested population groups, show a very low infestation one month after a single treatment with DDT powder. Monthly powder- ing of native labor groups should almost eliminate all risk of such groups spreading typhus to the people with whom they come in contact. 3. MYL is more rapidly effective than DDT but has a more limited residual action. DDT continues to intluence the degree of lousiness for several weeks. 4. The mechanical application of insecticide without removal of the clothing gives results comparable with those observed after careful hand application. There is some suggestion in the results that the insecticide blown forcibly into the texture of the clothing may have a more prolonged effect than has insecticide shaken on the cloth. 5. Vermin infested populations welcome the application of insec- ticidal powders and will make some effort to be treated. The choice of administrative technique used will depend on the distribution of the population to be treated, the existence of transportation faci- lities, and the personnel available to do the work.