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 <dusting of indivi,duals should follow a certain routine to avoid
missing some parts of the `clothing as must occur at times where each
person is handled differently.  The following routine has been found
useful :

1. - ilust inside of hat and replace hat on head.
2. -- With arms extended at shoulder height at the sides (not in front
of the body) insert delivery tube up first the right and then the left sleeve
and pump powder in between the skin and the innermost garment.
Powder should reach well into the armpit ansd the position of the gun
should he shifted to get powder all about the shoulder.
<r In case the subject is wearing more than one layer of clothing, dust
shou,ld be applied between his underwear and shirt as we11 as between
the underwear anld the skin.

3. - The `delivery tube is next inserted at the back of the neck and
a lrberal char#ge of powder shot down the back, care being taken to dust
the neckband itself.

4. - The tube is next inserted inside the clothing from in front and
powder sprayed first on one side, then on the chest and lastly on the
other *side, special care being taken to again rea'ch the armpit's.
5. - The tube is next inserted, after the trousers are loosened, inside
the innermost #garment and a good dose of powder delivered to the crotch
and pubic area. With the tube still in contact with the skin, the under-
clothing is powdered, special attention being paid to the waist and side
seams.

6. - With the trousers still loose, the tube is, inserted down the rear
of t,he pants next the skin and powder is shot down over the buttocks nnd
rear of the crotch,
o Note : if more than one layer of clothing is being worn, steps 3, 4, 5
and 6 shove are repeated for the second layer from the skin. )I

SECTION I : STUDIES A+ iHE MAISON-CARRliE PRISON

The Maison-Carree Prison had, at the time of these studies,
approximately 1,000 prisoners, accomadated in three war,ds, two for
males, one for females. Only small demonstrations were attempted
in the ward for females and no further reference will be made to
the work there.  The male prisoners, most of whom were Arabs,
differed in prison status, clothing and living conditions.

A considerable number of prisoners were employed as trusties
in handling the others.  These trusties received better food, cloth-
ing and quarters than did the other prisoners.  Special concessions
were made also for mechanics, cooks and other specialized workers.

Some prisoners,  especially those serving short sentences, had
friends or relatives with sufficient funds to supply them with extra
food, soap and clothing. These were considerably better off than were
prisoners depending entirely on prison issues. The latter were
obviously under-nourished and had little or no soap for washing

t. XXIII, no S, septembre 1945.


192   F. L. SOPER, W. A. DAVIS, F. S. MARKHAM, L. A. RIEBL, P. BUCK

the trousers, jacket and blanket which comprised their entire
wardrobe.

The prison routine calls for the use of woolen clothing in winter
and heavy cotton in summer. Due to the war and scarcity of mate-
rials, summer ,clothing ha,d not been issued to many of the priso-
ners and numbers of them continued to wear winter woolens
throughout the summer.

The work of the prisoners at Maison-Carree varied according to
the length of sentence imposed. Thus the prisoners in Ward I were
of two groups, those condemned for life and those confined for
minor offenses.  The minor offenders were hired out in gangs to
do agricultural work outside the prison grounds, whereas the lifers
worked in the open courtyard of the ward at relatively light la,bor
weaving mats and baskets for which they received a small stipend.
The lifers in Ward `I had not been issued summer clothing whereas
most of the short termers wore cottons.

The majority of prisoners in Ward II had been, sentenced to
forced labor. These men worked at hard physical labor preparing
fiber for basket and mat weaving. This work was .done under guards
in a large room where the prisoners were crowded together on the
floor.

Prisoners in both Wards I and II were provided with ilber mats
and blankets and slept in groups of 80 in large dormitories where
they were confined from 5:30 in the afternoon until 7 AM.

Because of the intimate contact and crowding, particularly in
Ward II, the opportunity for a daily interchange of parasites was
excellent. Under these conditions only the most industrious of the
prisoners were able to keep themselves relatively free of lice. The
steam sterilization plant at the prison was little used, because of
shortage of fuel and mechanical breakdowns.

The first visit to Maison-Carree was made on 23 July with
Dr. BBGUET at which time arrangements were made with the Direc-
tor of the prison for beginning work. Work began with a preli-
minary pre-powdering louse survey, July 26 to 29.  This survey
(Table I, Groups 1, 2, 3, 4) revealed 153 lousy prisoners among
158 examined, 116 of whom had more than 10 lice each. Further
surveys of unpowdered individuals were made from this time on
through the end of October (Table I, Groups 4, 13, 14, 23 and 24)
with the Anding of even higher degrees of infestation. From these
results it is clear that any reduction from the July level noted in the
louse burden of test groups must be attributed to the insecticide used.

The materials and methods used on 24 groups of prisoners at
Maison-Carree are outlined in Table II.

Experiment I

The initial test at Maison-Carree was to compare the action of
repeated d.oses of 5 7'0 DDT in barytes and of MYL on natural

Arch. Instltut Pasteur d'AlgWe.


LOUSE POWl&R STUDIES IN NORTH AFRICA       193

infestations in an environment where exposure to reinfestation from
untreated persons could be almost entirely prevented.
Ward I was chosen for the first test, with observations in Ward II
to serve as a check against the possibility of a seasonal reduction
of louse incidence being attributed to the use of insecticide.
The prisoners were called by number and checked off as the
clothing of each man was dusted by hand (shaker tins).

TABLE I:  LOUSE COUNTS ON UNPOWDERED GROUPS
        AT MAISON-CARRI~E PRISON

711649     1    4, 9, 3    108     104     77     71     96    10 +
__-_____
         a      4      50     49     89     78     98    10 +
________ ~--
819       2      4      C8     48     41     92     160     10 +
                  -- - __
8129      a    13,14     10     20     $0     ml     100    46 +
___~_I______- - __-
g/6      2    i3,44     20     20     17     85     100    40 +
       _____--- ___~-
9113      a    13,14     20     20     20     100     100    10 +
___.       -___ ___ __ - - __ ---
9jso      a     13,lb     20     49     i6     84     95    a9
____I_ ___-       -I_ ___ -
g/27      2    43,14     17     17     15     88     100     38
~~ __-___       --
9 30      2    23,2b     20     20     I8     90     100     37
~- ---I____-~-
NW      a    23,24     49     19     47     86     loo     12
___- ---__---
10/G      4    23,24     48     18     17     9b     100    (57
-_--       -___ ___ _____--~-
IO/12      2    23,2k     18     18     46     69     100    102
       ___---_______~-
101'19      2    'A$24     18     48     15     83     loo     90
-

The 108 men examined in Ward I (Groups 1, 2, 3) were divided
into three groups of 36 men each, and hand dusted (shaker tins)
as follows :                                                /
The clothing and blankets of the men in Group 1 were treated
with 5% DDT in barytes (barium sulphate) and redusted with the
same material 17 days later ; those of the men in Group 2 were
dusted twice at a 7 ,day interval, and those of Group 3 twice at a
14 day interval with MYL.

All other inmates of Ward I were treated with MYL twice with
an interval of 14 days to prevent them from grossly reinfesting the
study groups.

t. XXIII, n* S, septembre 1945.


194  F. L. SOPER, W. A. DAVIS, F. S. MARKHAM, L. A. RIEHL, P. BUCK

Arch. lnstitul PaSteUr d'AlaCrie.


LOUSE POWDER STUDIES IN NORTH AFRICA

195

Insecticide MYL was applied also to the garments of all new pri-
soners coming to Ward I and to those returning to the ward after
a stay in the prison infirmary.

So far as is known, the only prisoners in Ward I to escape the
initial dusting were three who assisted the guards in the adminis-
tration of the ward and 15 who wor'ked in the `bakery. T:hese
assistant guards were dusted three days and the bakers 13 ,days after
the rest of the prisoners.  This failure to dust all simultaneously is
probably of little importance, since these 18 men all enjoyed spe-
cial privileges, had separate quarters an'd were much cleaner than
the common run of prisoners.

The clothing and blankets of Groups 1, 2 and 3 were examined
at intervals after both first and second treatments.  In pre-
treatment examinations,  counts were discontinued on any given
individual when 10 lice had been foun'd, but post-treatment exami-
nations covered the entire inner surface of all clothing worn and
both sides of blankets.

The first post-treatment counts on Groups 1, 2 and 3 showed that
both DDT and MYL had been very effective in reducing the louse
burden of the treated prisoners (Table III). The two to four day
counts indicated that the immediate effect of DDT had been
somewhat less than that of MYL, but the 7, 10 and 14 day counts
definitely favored DDT.  The DDT-treated group showed a steady
decline in numbers of lice up to the 17th day', when it was
retreated.  The hatching of young had apparently ceased by the
10th or 11th `day.  In the MYL treated groups, 2 to 4 `day counts
were lower than 7 day counts and in the group not re-treated until
the 14th day, there was a decline in the louse infestation between
the 7th and 14th days with hatching of young forms practically
nil between the 10th and 14th days.  The striking reduction in
adult forms in all three groups is most significant, since the egg
laying function on which the species depends for continued exis-
tance is a function of adult life.

The second treatment of Group I with DDT seventeen days after
the first, was followed by examinations at 7, 13, 25 and 39 days
after this second treatment, with practically no lice being found.

TKe last examination of this group, made 67 days after the
second treatment (83 days after the first treatment) showed that
about a third of the group was again lightly infested.  This infes-
tation was so slight that the prisoners still considered themselves
louse-free.

,  Examinations of the MYL treated groups (2 and 3) failed in both
cases to reveal the presence of an appreciable number of lice for
some weeks. As was to be expected, evidence of reinfestation was
found earlier, in groupe 2, retreated after 7 days, than in groupe 3,
which was re-treated at an interval of 14 days.

t. XXIII, no S, septembre 1946.


196  F. L. SOPER, W. A. DAVIS, F. S. MARKHAM, L. A. RIEHL. P. BUCK

. .
u

I I I
. . . . . .
-2-t
=

Arch. Instltut Pasteur d'Alg&te.


LOUSE POWDER STUDIES IN NORTH AFRICA        197

In all three groups, negligible infestations were found at the
end of 56 days after first treatment.  The difference in the degree
of infestation of groups 1 and 3, re-treated after 17 days and 14 days,
and of group 2, retreated after only 7 days is probably significant.

Discussion. - A study of the behaviour of the louse population
on groups 1 and 3 before re-treatment suggests that for the maximum
result with the minimum amount of insecticide, the period between
treatments may well be longer- than 17 and 14 days.

Theoretically an insecticide which is fully effective immediately
against all froms present except the ova but which has no delayed
residual action should be repeated at about 14 days to catch the
early post-treatment-hatched lice before them come into active egg
laying. With the demonstration of continued activity of the insec-
ticEde this period may be lengthened accordingly.

From the epidemiological standpoint, it should be emphasized
that the post-treatment counts are  complete, counts based on a
thorough search in the seams of the clothing and an examination
of blankets. The degree of lousiness found 83 days after treatment
began was not such as to have permitted the rapid dissemination
of typhus in the ward, had it been introduced. It seems reasonable
to suggest on the basis of these counts that a population which has
been thoroughly powdered twice may he considered safe from
important outbreaks of typhus for at least a three month period.'

The results in Ward I suggest that the complete eradication of
lice in an institution or even in a community may be feasible with
the proper application of either MYL or DDT.

Experiment II

Experiments II and III carried out in Ward 2 were designed to
test, un,der conditions favoring reinfestation, the action of single
doses of 5% DDT, of 10% DDT, prepared in various ways and of
factory prepared MYL, applied in various ways. An additional
accidental variable was introduced in Experiment II through the
failure of mechanical equipment used to apply the same amount
of insecticide as was applied by hand.

Whereas in Experiment I, the possibility of reinfestation was
reduce,d to a minimum, reinfestation was favored in Experiments II
and III.  Only the clothing of the prisoners in these experiments
was powdered ; their infested blankets were ignored. The remaining
prisoners of Ward 2, where conditions were more favoraihle to rein-
festation than in Ward I, were not powdered.   Intimate con-
tact continued between treated and untreated in,dividuals both day
and night.

In Experiment II eight groups of ten men each were treated
with varying combinations of DDT, barytes and cement dust, some
by hand shaker application, and others by agricultural mechanical

t. XXIII. n* S, septcmbrc 1945.


198  F. L. SOPER, W. A. DAVIS, F. S. MARKHAM, L. A. RIEHL, P. BUCK

I '

. .
4

I- I

Arch. Imtttut Pasteur d.`Alg&fe.


LOUSE POWbER STUDIES I& NORTH AFRICA       199

t. XXIII. n. 3, septembre 1945.


200  F. L. SOPER, W. A. DAVIS, F. S. MARKHAM, L. A. RIEAL, P. BUCK

duster (Toxine) without removal of the clothing. This was the first
attempt to dust mechanically any considerable group of people.
Unfortunately, owing to an unrecognized defect in the duster used,
only about one-half as much insecticide was used on the machine
dusted groups as on the shaker dusted groups.

The results of Experiment II (Table IV) are not as clear cut as
one might wish, due in part to the large number of variables present
It is apparent, however, that even in the face of constant exposure
to reinfestation, six of the eight test groups treated with the
variously prepared an,d applied insecticides, had greatly reduced
louse burdens one month after a single application.  Only in
groups 5 and 7, in which about one-half of the usual amount of
5% DDT per person was used, fere the results poor. That these
poor results were to he attributed to the small amount of DDT
acfually applied rather than to the method of application is sug-
gested by the fact that the same amount of 10% DDT applied in
the same way (groups 9 and 11) gave satisfactory results.

The data suggest that good results can be gotten when an ade-
quate amount of 5% DDT is used, but that 10% powder affords a
better margin of safety.

Epidemiologically, these results indicate that monthly powder-
ing with DDT of persons subject to constant reinfestation will pre-
vent them from becoming an important source of typhus disse-
mination.

No significant evidence was found for the superiority of solvent
mixed over mechanically mixed powder.  There is some suggestion
that barytes may he a better diluent than is cement dust.

Experiment III

Although the results with cement dust in Experiment II were not
quite so' favorable as those with barytes it was felt that the great
advantage in weight justified further tests of DDT in cement dust.
Experiment III was set up in Ward II, under conditions favoring
heavy reinfestation to test :

(1) 10% DDT in cement dust, to which had been added 2% cresyl
acetate, applied by agricultural duster (Corona) by hand.
(2) 10% DDT in cement dust without cresyl acetate applied by
agricultural duster (Corona) and by hand.
(3) MYL ap,plied by Dobbins No. 133 duster and by hand.
(4) Repeated hand picking and removal of lice from clothing.
The results of Experiment III (Table V) suggest the following
conclusions :

1. DDT is slow to act but continues to exercise an influence on
the louse population for several weeks.
2. The addition of 2% cresyl acetate to 10 % DDT powder is
without apparent advantage.

Arch. Instttut Pasteur d'Alg&te.


LOUSE POWDER STUDIES IN NORTH AFRICA        201

3. MYL is more rapidly effective than is DDT but has a more
limited residual action.

4. The mechanical application of insecticide without removal of
the clothing gives results comparable with those observed after hand
application. There is some suggestion in the results that the insec-
ticide blown forcibly into the texture of the clothing may have a
more prolonged effect than has insecticide which is just shaken on
the cloth.

5. Weekly hand picking of lice from the clothing does not appre-
ciably reduce the total louse population where reinfestation with
adult egg-laying forms occurs constantly.

OBSERVATIONS ON LOUSINESS MADE DURING THE COURSE

OF EXPERIMENTS I, 11 AND 111.

It is apparent under the conditions of life at the Maison-Car&e
Prison that the great majority of viable ova hatch before the 10th
or 11th day after egg laying ceases.  The fact that this period is so
short may be in part explained by the fact that the prisoners wore
their clothing day and night and that the warm weather persisted
during the first two experiments.

The number of lice found on a given individual often varied from
week to week in the absence of treatment. This was sometimes due
to changing clothes, to washing clothes, and to very recent hand
picking of lice.

Very few `head lice were seen, possibly because the beads of the
prisoners are close-clipped periodically.

Surprising numbers of lice and some ova were found on the
blankets which were used only at night. The blanket undoubtedly
served as an important source of reinfestation in Ward II where
blankets were not powdered.

Lice were found to show a distinct preference for certain regions
of the body. The seams at the armpit, the neck, the waist and the
crotch were particularly favored. When only a few lice were pre-
sent, they -were generally confined to these areas.  On the other
han.d, when a prisoner was heavily infested, lice were found widely
distributed all over the clothing and bedding.

A very noticeable preference was noted for certain types of cloth.
Cases were observed in which several hundred lice were present on
the shirt with practically none on the trousers. In other cases large
numbers of lice were counted on the trousers with few or none on
the shirt.  In these cases the distribution was correlated with the
material and weave of the cloth in the garment. Those making the
observations in the prison came to know which types of cloth were
favored by lice and could pre'dict the distribution on a given indi-
vidual before examination.

c. XXIII, n* 3, septemtve 1945.


202  F. L. SOPER, W. A. DAVIS, F. S. MARKHAM, L. A. RIEHL, P. BUCK

d
3
%
F

Arch: Znstttut Padcur d'Algt?te.


LOUSE POWDER STUDIES IN NORTH AFRICA        203

t. XXIII, no S, septembre 1943.


204  F. L. SOPER, W. A. DAVIS, F. 6. IABKHAM, L. A. RIEHL, P. BUCK

Arch. Znsfttut Pasteur d'Atgt?rle.


LOUSE POWDER STUDIES IN NORTH AFRICA        205

The average louse count increased rapidly after the cool weather
began. The weather during July, August and September was hot and
clear but a sudden change to colder and rainy weather came early
in October. The louse count rose rapidly at this time (Table I,
Groups 23, 24).  This may be attributed to the fact that without
adequate changes of clothing the men ceased to remove their cloth-
ing for washing, tended to huddle together indoors and often wore
tbeir blankets both day and night.

SECTION II :

FIELD PROQRAM IN L'ARBA COMMUNE, ALGERIA

The work at the prison had established the efficacy of MYL and
DDT on peopIe naturally infested with lice, but contlned within
n.arrow limits and subject to prison discipline. Before undertaking
epidemic control with the methods used in the prison, it seemed
desirable to get experience in delousing a civilian population in
which individuals were free to come and go as they pleased. Dis-
cussions with Dr. Edmond SERGENT and Dr. BBGUET of the Institut
Pasteur, Algiers, and Dr. GRENOILLEAU, Director of Health for Algeria,
led to the selection of L'Arba, which Ties some 30 kilometers south
of Algiers, as the site for such a study. Late in August, the com-
mune of L'Arba was visited and the approval of the mayor and the
Caid obtained for a delousing program, to begin in October, after
the end of Ramadan.

Typhus had been present in L'Arba during the seasons, 1941-42
and 1942-43. Within the town proper live approximately 1500 Euro-
peans, mostly French, and 3.500 Arabs. That lice were present in
the community was demonstrated on the first visit. Rapid exami-
nation of the collars and shoulder yokes of the upper garments of
several boys at the school, showed all to have lice.
It was hoped that information could be gained from the work
in L'Arba on :

(1) means of establishing contact with and handling the people
to be treated ; (2) methods of applying delousing powder to free
civilians ; (3) type of records to be kept ; (4) availability of labor
for the delousing of Arab populations.
It was decided that the delousing work at L'Arba would she based
on the use of two applications of MYL powder per individual with
an interval of fourteen days between applications.
Planning of the work provided for completion of all first treat-
ments within three weeks and more than four weeks from the day
the work started in the community,

t. XXIII. R' 3, septembre 1945.


206   F. I.. SOPER, W. A. DAVIS, F. S. MARKIIAM, L. A. RIEHL, P. BIICK

PRELIMINARY TRIAL IN LOTISSEMENT BUGEAUD.

It was agreed with local officials of L'Arba that a demonstration
of delousing methods would be conducted in Lotissement Bugeaud,
a section of ward-like subdivision near the town hall with some
600 inhabitants, mostly Arab.

The initial demonstration followed the general plan used in
Mexico. The streets in the section were not named, and the houses
did not have numbers.  The first step, therefore, was the drafting
of a map to orient teams of held workers.

The actuel work of delousing began on October 11, 1943.
Workers were organized into 3 teams of 3 members each - one
person having had experience in the work at Maison-Car&e plus
one male and one female assistant. Two of the women were French
Public Health nurses.  The third was an Arab girl, about 15 years
old ; permission had been o.btained from her family for partici-
pation in the work, and it was hoped that her example would
encourage other Arab women to accept employment.  It was anti-
cipated that the experience gained here would qualify these women
for later supervisory work.

The population of the lotissement was divided into three approxi-
mately equal portions, and a section assigned to each team.  The
team carried a basket containing the following efquipment : a map
of the lotissement, a clipboard with two sets of forms, one for
recording census, louse incidence and powdered individuals and the
other a daily team summary, a piece of chalk for marking the house
numbers, a flashlight, a supply of MYL powder in a-ounce paper
envelopes, a Dobbins < Superbuilt > 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.