Malaria in the Kirkuk division of Northern Mesopotamia during 1923

41

COMMUNICATIONS. ALARIA

IN

THE

KIRKUK

MESOPOTAMIA WILLIAM

DIVISION

OF

DURING

CORNER, O.B.E., M.D. Iraq Health Seruice.

NORTHERN

1923.” (Aberdeen).

L The writer had not occupied the position of Civil Surgeon in the kirkuk D’ rvision very long before it was evident to him that. although malaria was a factor of prime importance in causing ill health among the local people, yet he was in considerable ignorance as to local malarial condiIgnorance was felt, for instance, when it became tions and manifestations. necessary to give an opinion on the healthiness or otherwise of a certain district, town or village, or to give advice to troops as to when anti-malaria prophylaxis became necessary and when it could be stopped, advice which entailed a knowledge of the malaria season or seasons. There was ignorance, also, of the part played by each malaria parasite in the genera1 infection. During 1923, therefore, systematic observations on malaria were made and from them this report was compiled. These observations consisted mainly of(1) examination of children for the estimation of the spleen rate; (2) clinical examination of fever cases including the taking and examining of blood-smears. Blood examinations were carried out continuously throughout the year, the number of cases examined being 1,768, of which Cases have been available from three 566 showed the malaria parasite. sources. (a) Civil Hospital out-patients (Kirkuk Town), (b) Cases seen on tour. Blood-smears from this source comprise more than half the total number taken. By doing a considerable amount of touring, the villages in a fairly wide area, between the Lesser Zab River in the north and the Dialah River-in the south, have been visited. (c) Native levies stationed in Kirkuk Town. About 100 bloods were taken from this source. Kirkuk is situated in the sub-montane country of Northern Mesopotamia, its altitude being roughly 1,100 feet above sea level, while the districts in which touring was done varied from an altitude of 600 feet or less, in the 1+x-t

*This report for 1923.

was submitted Also submitted

to the Iraq Iiealth Directorate in a less elaborated form as M.D.

in the thesis.

Annual

Departmenta

42

MALARIA IN NORTttERN MESOPOTAMIA.

case of villages on the desert side of the K i r k u k Division, to 2,000 feet i ~ the hilly parts. T h e climate is of the sub-tropical variety which, as in other~ sub-tropical areas, is favourable to the p r o p a g a t i o n of malaria at certaitl;! seasons only. T h e rainfall is almost entirely confined to winter and spring~{ T h e following are the main points dealt with in this report : - 1. Malarial p a r a s i t o l o g y a n d the malaria seasons. 2. A note on an average parasite count as a measurement of intensity of infection in quartan and benign tertian malaria, with clinicM observations on ail three int'ections. 3. A note on the prevalence of mosquitoes. 4. Malaria a m o n g tt~e nomadic A r a b s in the K i r k u k Division.: 5. A short note on the parasite rate. 6. T h e spleen rate. 7. Meteorological conditions and their relation to the malaria seasons. 1. MALARIAL P A R A S I T O L O G Y AND T H E M A L A R I A S E A S O N S . S t a t i n g the matter briefly, there have been two malaria seasons in 1923, (a) the main malaria season, very definite, lasting from the b e g i n n i n g of June to the middle of A u g u s t , due m a i n l y to the m a l i g n a n t tertian anT:l, to a lesser degree, to the b e n i g n tertian parasite. (b) A slight but definite malaria season in late October a n d November, due to the m a l i g n a n t tertian parasite. MALARIA IN 1922. The study of malaria in 1923 cannot be complete without a note on malaria in 1922. It would be well, therefore, before proceeding further, to consider its character. D u r i n g that year, unfortunately, no blood examinations were performed, only clinical observations being made. Tl'ie summer malaria season commenced ten to fifteen days later than that of 1923, and was characterised by a much greater incidence of the severer forms of the disease. M a n y of the cases resembled, clinically, the severer types of malignant tertian seen d u r i n g 1923. S o m e areas suffered more severely than others. In K i r k u k Town, for instance, the Jewish quarter was badly affected, and d u r i n g the first half of July one house was seen where practically the whole family was prostrated, from b a b y to g r a n d m o t h e r . D u r i n g the month of July, also, certain villages in the n e i g h b o u r h o o d of K i r k u k were so b a d l y affected that harvest operations threatened to come to a standstill. T h e regiment of native levies from K i r k u k , which at that time was operating in the Kurdisl~ hills between K i r k u k a n d Sulaimania, was severely affected, a large number of men suffering from fever while one British officer succumbed to it. O n the w[/ole, this m a l a r i a did not seem to be accompanied by a heavy rnortality (e.g., K i r k u k Jewish quarter), yet it

MALARIA IN NORTHERN MESOPOTAMIA.

43

found that one small village of about 100 inhabitants teath rate of 20 per cent., the proportion being five adults to This village was one of those referred to above as affectdd ~st. It is worthy of note that the winter a n d s p r i n g rainfall which the writer had personal experience, was exceptionally the heaviest d u r i n g the last four winters. T h e r e was ature of extensive flooding observed, as the fall of the land -apid drainage in the hilly parts, and a moderately r a p i d plains. This heavy rainfall was nevertheless p r o b a b l y , as ,erience of workers in India, responsible for the severity of t was severe enough to be called " e p i d e m i c " malaria, aot accompanied b y a h e a v y mortality such as characterises tria in some places, e.g., tlle P u n j a b . A g r a p h is attached tlA (CLINICAL) AMONG OUT-PATIENTS OF THE CIVIL HOSPITAL, KIRKUK, 1922and t923.

400

350.

300

250

2(}0 Z 150.

100,

50

1922

1923.

Showing t!le figures for malaria (clinically diagnosed) in the out-patient department of the Civil Hospital, K i r k u k , for 1922 and 1923. T h e relative severity of the two malaria seasons is shown an
44:

MALARIA 1N NORTHERN MESOPOTAMIA.

correctly indicated. It will be remarked that the late autumn season scarcely noticeable in either year, a point which will be referred to later. MALARIA IN 1 9 2 3 .

Systematic blood examination of fever cases commenced from the begin ning of the year. It was not long before it became evident that malaria, though common, consisted almost entirely of infections due to the parasite of quartan malaria. Month followed month, the weather became warmer! but still this marked quartan predominance persisted. Thus, from the begin, ning of January to the end of May this state of affairs held good, benign tertian and m a l i g n a n t tertian being relatively uncommon, especially the latter. There was an indication, however, that, towards the end of this period, b e n i g n tertian cases were b e c o m i n g a little more numerous. The occurrence of this unusual predominance of quartan malaria would be difficult to explain if one were in ignorance of the epidemic malaria conditions of the previous year. T h e r e seems no doubt that the whole of these quartan cases were residual infections from the foregoing year. F u r t h e r reference will be made to this matter later. W i t h the advent of the warmer weather a look-out was kept for newly infected cases and the usual difficulty was experienced in deciding between a new infection and a relapse. T h e first definitely fresh infection was found d u r i n g the month of M a y . T h e patient, a child of two months, was seen on 31st M a y in the village of Silukan suffering from quotidian fever of seven d a y s ' duration, which, on blood examination, proved to be a double infection b y the parasite of benign tertian; malaria. If one allows fourteen days as an incubation period, infection must have been contracted on or about 10th May. T h a t such a case must be regarded as u n c o m m o n l y early is shown, however, by the similarity of t h e blood examinations d u r i n g M a y to that of the previous four months of the year. T h e malaria season opened definitelv from about 1st June, with a rise in benign tertian cases. M a l i g n a n t tertian followed more or less abruptly from about 15th June. T h e m a x i m u m was reached d u r i n g late June and the first half of ~[uly, after which both infections subsided together, until by the second half of A u g u s t a return had almost been made to the pre-malaria season level, a study of the half m o n t h l y figures indicating, however, that the benign subsided slightly before the m a l i g n a n t form. W h e n the attached graph, showing the p a r a s i t o l o g y of malaria throughout the year, is examined, it will be noticed that it indicates an almost equal incidence at this time of b e n i g n and m a l i g n a n t tertian fever. On this point the g r a p h does not indicate correctly. Actually, m a l i g n a n t tertian, except d u r i n g the first half of June, markedly predominated. T h e reason for this will readily be understood when it is remembered that in m a l i g n a n t tertian

MALARIA

IN

NORTHERN

MESOPOTAMIA.

45

unless the crescent form is present, is as a rule falciparu% The the peripheral blood except during the actual fever attack. VaJ9e of malignant tertian infection was of the quotidian variety, &ming on in the late morning, afternoon or evening. Patients li$ to the out-patient department in the morning tended, therefore, p GRAPHS SHOWING PARASITOLOGY OF MALARIA. KIRKUK,

‘----. JAN.

\

MALIG. ‘, ../’ 7----FEB.

MARCH

APRIL.

1923.

\-----Y,, ‘\

MAY

J”NE

JULY

AUG.

SEPT.

OCT.

NOV.

\0 P *-.% DEC.

,923.

Irom this and other reasons, to be afebrile. Moreover, crescent infections were relatively uncommon, These facts accounted for only a relatively small Proportion of malignant tertian cases being bacteriologically diagnosed. On the other hand, the majority of benign tertian cases were probably detected.

4~

MALARIA IN NORTIIERN MESOPOTAMIA,

F r o m the middle of A u g u s t to the middle of October, fresh i n f e c t i o ~ were few or nil. The pre-malaria season ratios again appeared, quarta~ predominating, though not so markedly as before, while benign tertian and:~ malignant tertian were not common. :~ D u r i n g the end of October a slight rise took place in the malignant l tertian rate. which culminated in a small, though definite, malignant tertia~f predominance in the first half of November. T h i s rise did not seem to be shared by the benign tertian parasite. D u r i n g December there was a return to previous conditions, quartan malaria predominating. Reviewing the 3,ear as a whole, malaria was very prevalent during the first eight m o n t h s - - f r o m J a n u a r y to M a y because of the large amount of residual malaria from the previous year and from June to August because of the malaria season. D u r i n g the last four months of the year quartan had largely, and benign a n d m a l i g n a n t tertian almost altogether, died out, so that malarial infections were scanty and became scantier as the end of the year drew near, except for the slight rise in prevalence in late October and November. It might be well, before g o i n g further, to give additional points in support of the conclusion that the comparatively small rise of malignant tertian cases in October and November was due to the occurrence of a fresh infective period. 1. T h e writer was medical officer to a British battalion in I r a q in 1917 and 1918, d u r i n g which time the unit took part in the F a t h a h - - S h e r g a t operations (October, 1918). T h e F a t h a h - - S h e r g a t section of the Jebal H a m r i n hills stretches for about forty miles along the west bank of the T i g r i s and lies fifty or sixty miles west of K i r k u k . T h e T i g r i s north of B a g h d a d is more or less free from malaria until this area is reached (the F a t h a h - - S h e r g a t section m a y have been more malarious at the time of operations than now, as the T u r k i s h a r m y had been encamped in the vicinity for more than a year). U p till that time there had been very little malaria in the battalion, as, d u r i n g the whole of its time in Iraq, it had operated in non-malarious areas on the T i g r i s . On 24th October Fathah was reached, whereafter the troops worked northward, between the Jebal and the Tigris, to Shergat, where, operations culminating, the troops remained for about a month. D u r i n g the days immediately preceding and following the Great Armistice on l l t h November, the battalion was severely attacked b y malaria. Bacteriological examination was made on m a n y of these cases in Bagl~dad, and the writer, as medical officer of the unit, was informed of the diagnosis. T h e majority turned out to be m a l i g n a n t tertian infections. T h i s outbreak was clearly the result of a n o n - i m m u n e b o d y of men operating in a malarious region d u r i n g the infective season.

MALARIA IN NORTnERN MESOPOTAMIA.

47

revalence of m a l i g n a n t tertian was general, not local. D u r i n g nd November blood examinations were made from cases seen :ious parts of the Division, some as far south as the D i a l a h . all areas visited the predominance was slight, t h o u g h definite. ;econd malaria season was accompanied by an increased prevaheIes, a point which will be referred to later. )e well at this point to consider what explanation is accepted , the v a r y i n g relative proportions of the different species of [. CHRISTOPHERS is here quoted.1 W i t h regard to the parasite ertian he s a y s : " W h e n (in the tropics and sub-tropics) anophelism is intense, infection with P l a s m o d i u m falciparum . . . . at once becomes predominant. T h e r e is reason to believe that this is due to the greater gamete output of this parasite. Its power of relapse after long intervals appears to be less than the case of the other p a r a s i t e s . " With regard to P . malarice, the quartan parasite, he s a y s : " T h i s parasite in nature . . . . a p p e a r s in the absence of fresh infections as the most resistant f o r m . " With regard to the b e n i g n tertian parasite, P . vivax " h o l d s an intermediate position." S u m m i n g up he s a y s : " P u t briefly, predominance of P . faIciparum indicates anophelism and active transmission, predominance of the other parasites, a n d especially of quartan, indicates a greater or less degree of residual human infection. Obviously the introduction of a non-infective period, as in the case of the temperate regions, will favour P . vivax and P . mala~i~e." One's experience of malaria in I4irkuk d u r i n g 1923 is largely in agreement with these views. T h u s the predominance of quartan malaria from January to M a y was due to residual infections from the previous year. With the onset of the s u m m e r malaria season and the increased prevalence of malaria, m a l i g n a n t tertian became the p r e d o m i n a t i n g infection, while benign tertian occupied a secondary position. T h e g r a p h of m a l i g n a n t tertian malaria, as here given, with its abrupt rise, its rapid decline a n d the secondary rise in November, can be taken b y itself to denote the malaria seasons except that, as already mentioned, to be accurate, the malaria season seemed to open with a rise in benign tertian prevalence r o u g h l y fifteen d a y s before that of m a l i g n a n t tertian. T h e m a i n point of difference seems to be with r e g a r d to b e n i g n tertian malaria. T h i s infection, with its rapid decline more or less simultaneously with the m a l i g n a n t form, and the absence of a n y indication of relapses,

48

MALARIA IN NORTHERN MESOPOTAMIA.

resembled very closely the latter in behaviour. A point supporting th~ supposition that this is not a peculiarity of 1923 is the fact that althoug!~~ d u r i n g 1922 malaria was epidemic, yet d u r i n g the early months of 1923, when one might have expected a fairly heavy residual infection with benig~ tertian, this parasite was found to be responsible for very few infections: These facts would seem to indicate that the benign tertian infection in the area under investigation departs markedly, at least in indigenous cases, from its usual rSle in the causation of chronic malarial relapses. A l t h o u g h systematic blood examinations have been useful in indicating ~ and demarcating the season of prevalence of the m a l i g n a n t and benign tertian parasites, the same definite conclusions have not been drawn with regard to the season of infectivity of the quartan parasite. P r e s u m a b l y this period coincided with the summer malaria season, a supposition supported by the fact that many of the quartan patients seen d u r i n g the first five months o f the year affirmed that their infection dated from the time of the previous harvest and threshing of the wheat (June, July and August), at which time malaria was epidemic. But it has not been possible in 1923 to confirm this either by clinical or bacteriological observation. T h e r e seemed to be no indication of fresh infection in September, October and November, and a n y increase d u r i n g June, July and A u g u s t was hidden by the mass of already existing quartan malaria. T h e conclusion seems to be justified that the bulk of quartan infections met with in 1923 were residual infections from 1922, and that they underwent steady and progressive diminution up to the end of the year, fresh cases being relatively so few as to be unnoticeable. A s the g r a p h of quartan malaria is not, however, in agreement with this conclusion, an explanation is necessary. Its irregularity is due to the effects of touring. H a d observations been confined to hospital out-patients only, a rise in the graph would, in the absence of a n y disturbing factor, be due to relapses or fresh infections. But actually the number of blood examinations, and thus the number of positive results, varied according to the amount of touring performed in addition to the ordinary l~ospital work. Thus, the rise in the g r a p h from J a n u a r y to M a y was due to increased facilities and opportunities for touring month b y month, while the b e n i g n and m a l i g n a n t tertian infections were so scanty, except d u r i n g the actual fever seasons, that their respective g r a p h s were scarcely affected b y this increased touring. T h e rise in September and October is explained in the same way. T h e fall in June, July a n d A u g u s t was a relative one only and due to the fact that (1) with the increase of infection due to other malarial parasites quartan became relatively uncommon, a n d (2) the amount of t o u r i n g was reduced to a minimum, one's time b e i n g fully occupied in dealing with t h e malaria cases coming up to the hospital out-patient department. There seems no doubt that, j u d g i n g from available literature, such a

XALARIA

IN

NORTHERN

49

MESOPOTAMIA.

ce of quartan over benign and malignant tertian malaria, as uary to May, is remarkable and uncommon, and is not met marked extent in most other malarious areas in the subAn experience of the neighequent to epidemic malaria. uk, extending over about four years, has gone to show that areas, of which several have already been recorded, where This suggests a fuller aratively common infection. tion of the marked quartan predominance, viz., that it is due to 1 infections from an epidemic year occurring in an area in which is peculiarly common. en one has enquired, while on tour, from natives with regard to the ce of fever, it has often been heard stated by them that quartan which to them means -simple quartan) is commonest in the autumn, As already mentioned, there has been en the nights begin to get cold. evidence that at this season fresh infections are occurring. The probable nation is that benign tertian and malignant tertian having by this time or less died out, quartan becomes more noticeable. Another reason which seem to tend to be triple or mixed t@ay be that quartan infections, @fections to begin with, may by this time have become reduced, to a certain %&tent at least, to simple infections. There was no evi$ence that quartan malaria was confined to any one area of the Division. It was found equally in the villages on the edge of the desert and in the hills, and from the Lesser Zab River in the north to the Dialah River in the south, a distance of about one hundred and thirty miles. Before passing from the subject of quartan illalaria it might be mentioned that it has been rare to find a quartan infection in Europeans who have contracted malaria locally. But no conclusion can be drawn from this, as one’s experience has been almost entirely among the local population. Quartanmalaria also seemed uncommon in children under one year of age. 2. A NOTE ON AN AVERAGE PARASITE COUNT AS A MEAS~JREMENT INTENSITY 0~ INFECTION IN QUARTAN AND BIWIGN TEKTIAN MALARIA, CLINICAL OBSERVATIONS ON ALL THREE INFECTIONS.

OF WITH

All blood examinations were personally done, the same microscope being in use throughout the year. All patients were seen and had their histories noted and bloods taken personally, except in the case of Levy patients whose bloods were taken by the sub-assistant-surgeon in charge. In dealing with positive slides, in addition to noting to which parasite infection was due, a count was made of the number of parasites found. In quartan infections parasites were always comparatively scanty and uniform in numbers, and 200 fields were counted in each case. In benign tertian infections the number of parasites present was inclined to vary,

O0

MALARIA

G~J~PHS S H O W I N G

IN NORTHERN

MESOPOTAMIA.

C L I N I C A L V A R I E T I E S OF Q U A R T A N MA L A R I A ,

192~.

TOTAL QUAR

50-

w/ o

40

~ 3o N Z

G R A P H S S H O W I N G M O N T H L Y A V E R A G E O F P A R A S I T E S PER 200 F I E L D S IN Q U A R T A N CASES•

15

O. -,.

",% AL QUARTAN CASES

g

<

~'Q"

•

//~le

0

JAN.

FEB.

MARCH

APRIL

MAY

jUNE

JULY

AUG.

SEPT

OCT.

NOV.

DEC.

MALARIA IN NORTHERN MESOPOTAMIA.

51

very numerous, and the plan was adopted of c o u n t i n g ,r of fields according to the prevalence or otherwise of the .xsites were very numerous, fewer fields were counted and 3sult being finally calculated to 200 fields. T h e average tes per case of quartan and benign tertian infection each found, and the results are given in g r a p h i c form. QUARTAN MALARIA.

are given of the parasite count. age number of the parasites found in 200 fields in simple (monthly). r count in total quartan cases, including single, double )ns.

ticed that the highest average parasite counts were regisning of the year and that a fairly steady diminution took mnth, a feature specially marked in simple quartan cases, end of the year,.simple quartan infections could show no Hore than one or two parasites in 200 fields. T h i s is a s t r o n g proof in ~avour of the statement, already made, that the majority of quartan infections met with were old infections contracted d u r i n g the previous year a n d that they underwent steady and progressive diminution month b y month. H a d fresh infections occurred to a n y m a r k e d extent d u r i n g the s u m m e r or autumn, a rise in the parasite rate m i g h t reasonably have been expected. Three things seem to have been h a p p e n i n g month by month. (a) A progressive diminution in quartan incidence. (b) iA_ progressive diminution in the severity of s y m p t o m s in quartan cases met with. (e) A progressive diminution in the number of parasites in the peripheral biood of cases, with a n increase in the proportion of clinically definite quartan infections found negative b y microscopic examination. Quartan infections have always tended to sliow uniformity each month in the number of parasites found in each case. T h a t is to say, if the a v e r a g e nmnber of parasites in 200 fields for a particular month in simple quartan cases was found to be eight, the parasite count in each individual case did not v a r y m a r k e d l y above this figure. These figures, as shown on the graph, indicate very well, from a bacteriological point of view, the remarkable chronlcity of the infection, the uniformity of the degree of infection, a n d the r e g u l a r a n d uniform way in which it g r a d u a l l y dies out. As a clinical illustration of the types of infection met with, the following cases are given from a m o n g those seen d u r i n g M a y . T h e y were confirmed by microscopic examination. Simple Quartan Malaria.--Patient, a male, a g e d 20, from the village

~

MALARIA IN NORTHERN MESOPOTAMIA.

of Tiseen, two miles from K i r k u k . Complaint : - - o n e d a y fever two dayl free, the fever coming about three hours after sunrise ancl leaving hi'~ about sunset time. Duration 10 months with intermissions. The patien~ is unable to work when fevered, but able to work once it passes. He loom yellow and anaemic, but otherwise is well-nourished and not emaciated£ T h e spleen is enlarged to the umbilicus (probably p a r t l y due to previou~ infection or infections) and is painful. Double Q.uartan MaIaria.--In this case the two infections giving the double quartan fever differ in time of onset a n d severity. T h i s has been an unusual feature in the other double quartan cases met with. Patient, a female, a g e d 36, from the village of Hissar, 15 miles to the desert side of K i r k u k . Complaint : - - t w o days fever one d a y free. T h e first d a y ' s fever comes at noon and lasts until sometime into the night. T h e second day's fever is always worse and starts sometime after noon. Duration of double quartan fever is two months. Fever started, however, at least five or six months before, at that time coming every d a y (mixed or triple infection). Spleen not examined. Triple or Mixed Quartan MaIaria.--Patient, a female, aged about 86, from the village of Tiseen. Complaint :---severe daily fever for fifteen days, the fever c o m i n g about m i d d a y and leaving about m i d n i g h t . History of first onset not dependable. H a d quartan fever seven months ago for one month, whereafter she took quinine and the fever left for a month or so. T h e n it returned and continued with intermissions to within a short time of examination. Quotidian fever started fifteen d a y s ago. T h e spleen is enlarged a handbreadth below the costal m a r g i n but is not painful. Graphs are also given illustrating the relative prevalence of simple, double and triple quartan malaria t h r o u g h o u t the year. BENIGN TERTIAN MALARIA.

T h e g r a p h showing the average number of parasites in 200 fields in simple benign tertian cases is given. T h i s indicates how, with the onset of the summer malaria season, an increased intensity of infection, as measured b y an increase in the average number of parasites per case, accompanied the rise in prevalence of the infection. T h e same degree of reliance cannot, however, be placed upon this g r a p h as in the case of quartan malaria. A certain amount of difficulty was often found in d e c i d i n g whether cases were double or single infections. This h a p p e n e d where the blood examination gave no special indication, and where the history did not definitely point to a quotidian or tertian infection, as in the case of y o u n g children, or where the history was v a g u e or unreliable. Moreover, benign tertian cases have often tended to show great variation in the number of parasites present in the peripheral blood which were sometimes scanty,

MALARIA E 4HnWING

CLpmAL

IN

NORTHERN

VARIETIES

I I

OF BENIGN

i

1

#

0’

\

TERTIAN

MALARIA,

1923.

\

\

, I I

)vLuBgy

53

MESOPOTAMIB.

\ t

,

Y.g */

JAN.

FEB.

hlARCH

APRIL

GRAPH OF MONTHLY

MAY

JUNE

JULY

AUG.

AVERAGE OF PARASITES PER 200 FIELDS BENIGN TERTIAN CASES.

* JAN.

FEB.

MARCH

APRIL

SEPT,

MAY

JUNE

JULY

AUG

SEFT

OCT.

IN

OCT

NOV.

DEC.

SIMPLE

N0V.

DEC.

54

MALARIA IN N O R T H E R N M E S O P O T A M I A .

sometimes very numerous. F o r this reason the examination of a larg~ number of cases than were available, especially in the early and later mont~ would be necessary to permit of a fair average b e i n g struck. It seems faifl probable, however, that the g r a p h indicates what actually happens and t~i the examination of a large number of bloods would give the same resuh A similar graph for double benign tertian was prepared, but was fou~ too erratic to be given, m a i n l y because of a few comparatively hea~ infections which occurred d u r i n g the early a n d late months when the nurnb~ of cases met with were too few to permit of a fair average b e i n g struck. :~; G r a p h s are also given showing the prevalence of simple and doub~ infections. T h e clinical features of benign tertian cases call for no remark. GRAPH SHOWING PROPORTION OF CASES OF MALIGNANT TERTIAN IN WHICH CRESCENTS WERE FOUND.

40

TOTAL

33"

SES.

30. ¢g 25~ < ~9 2O

/ JAN,

FEB. MARCH APRIL

MAY

c sc TS. ',,kJ r JUNE"

JULY* I923.

AUG.

SEPT.-

~¢

OCT.

•

\

,"".,\ NOV, DEC.

MALIGNANT TERTIAN MALAFdA. In the case of this infection a parasite count is not comparable to that of benign tertian and quartan, since the non-sexual parasite is only present in the peripheral blood d u r i n g the r i n g stage. A g r a p h is given of the number of cases in which crescents were found. It must be understood,

MALARI.1

IX

SORTHERN

MESOPOTAMIA.

crescent infections were and August, crescent graph representing the number .I malignant tertian bloods examined, many of were found negative. A prolonged search for ks, h&vever, not made. &non malignant tertian infection met with during the summer l&an fever, of no great severity, lasting often only four or five in the late morning, coming on, usually without much shivering, Schoolboys were sometimes found attending school Continuous and remittent lthough attacked by fever at night. etimes of a fairly severe type, were also met with, but less com&&m the quotidian variety. The pernicious manifestations of this gpn, e.g., cerebral, etc., were conspicuous During by their absence. immer malaria season of 1922, the quotidian type of fever, many of cases were presumably ma&ant tertian infections, was also on. The following is an example of a case of the quotidian variety with in June, 1923. Complaint :atient, a boy, aged 13, seen in Kifri on 19th June, 1923. days’ quotidian fever. Fever comes about noon and leaves at sunset. ed no fever at time of examination. States that though fever is severe @sile it lasts he is able to work when it leaves him. Blood examination &rowed a few late malignant tertian rings. 3.

PREVALENCE

OF MOSQUITOES.

Malaria in Kirkuk does not seem to be accompanied by a marked degree of anophelism, and for this reason detailed observations on Anopheles would have consumed more time than was at one’s disposal _ It has, therefore, been taken for granted that the main malaria carrier in this Division is Anopheles szrperpictus, as established by C~RLSTOPHERS and SHORTT,~ although they also found A. maculipe~~is-in Kirk& Town but regarded it as of subsidiary importance. The only observations which have been made have been to notice the time of starting the maximum increase, and the variation in the mass of mosquito breeding, without doing more than notice the rerative Prevalence of C&x and Anoplzeles. I hesitate to include these observations, for, to be accurate, observations should be made on the particular malariacarrying mosquito or mosquitoes of the neighbourhood, but I have included them as there seems in this case to be a definite relation between the general increase of mosquito breeding and the increase of malaria. This is probably due to the fact that the increase of the local malaria-carrying mosquito synchronises with the general mosquito increase. TO put the matter briefly, two such periods of increase took place, the first in May and the second in October. Refore the beginning of May

36

MALARIA IN NORTIIERN MESOPOTAMIA.

anopheline and cuticine mosquitoes were sometimes found flying a~ indoors, especially when tt{e weather 16ecame warmer. Breeding ~ occurred, must, however, have been present in a scanty manner, as no ta~ were noticed in the ordinary pools which were largely used as breeding-pl~ later on. B r e e d i n g first became noticeable on 7th May. It increM rapidly, until by 23rd M a y a marked increase had taken place, certain p~ literally s w a r m i n g with larvae a n d pupae. T h i s was due mainly to increase of the Culex variety, although anopheline larvae were also comm0~ Certain small isolated puddles, such as would occur from the footprints~ cattle in m a r s h y ground, were found showing o n l y anopheline lar-~i A l t h o u g h it is certain that this general increase in breeding must have bee~ followed by an increase of Anopheles in the quarters of the town near a{ hand, yet this increase was not very noticeable. J u d g i n g from their humbert~ in the town, one would not have t h o u g h t ttiat malaria was capable of being~ p r o p a g a t e d to a n y great extent b y their agency. T t i r o u g h o u t the very h0f weather of July and A u g u s t b r e e d i n g could always be found, though on a reduced scale. T h e second occasion on which a marked increase of breeding was noticed was about the first week of October. T h i s increase was even greater than the first, only the anopheline larvae, t h o u g h increased, seemed to be in a smaller proportion than formerly. It was followed d u r i n g the second half of the month, especially towards its end, by a great increase of mosquitoes, mostly CuIex. T h i s was the only time of the year when one would have said that mosquitoes were really prevalent. W i t h the onset ot~ the cold weather, breeding" rapidly diminished. These observations, rough t h o u g h they are, show that the summer malaria season of June, July and A u g u s t was preceded by a rise in mosquito prevalence, including Anopheles, in May, and the ktte autumn season was preceded b y a similar rise in October. 4.

MALARIAAMONG THE NOMADIC ARABS IN THE KIRKUK DIVISION.

It m i g h t be expected that the nomadic Arabs, living, as tl~ey do, in the desert, and leading almost altogether a pastoral life, would not suffer from malaria. But this is not altogether the case. it is true that on the whole there is very little malaria to be found a m o n g s t them, but it varies, a n d both the occurrence of malaria and its variation can be explained b y their habits. These A r a b s are real desert dwellers, i.e., dwellers in the midst of the desert only d u r i n g winter and spring, a n d the length of their stay there depends on the rainfall. W h e n sufficient rain has fallen to fill the desert pools and to cause sufficient grass to s p r i n g up, they move out into tile clesert, and when the a p p r o a c h i n g summer burns up the grass and dries up the pools, they move back to their summer and autumn quarters. These quarters

MALARIA IN NORTHERN MESOPOTAMIA.

57

fixed, each tribe or section of a tribe having its own recog,~rounds. Some move down to the T i g r i s , some to the f the K h a s a Chai a n d the T a u k Chai, some to the lower esser Zab, while some camp near the fringe of villages to Taza K h u r m a t u side of the desert, d e p e n d i n g for their ,rater supply of the villages, which is often r u n n i n g kariz ated tents were also met with d u r i n g the summer, e n c a m p e d villages near the hills. These A r a b s were usually found ~epherds of the head man of the village, t a k i n g the sheep the wet season and b r i n g i n g them back to the village for he time of m o v i n g into s u m m e r quarters varies with the extent of the rainfall. D u r i n g 1923 it was found that b y the end of Arabs had moved into their hot-weather c a m p i n g g r o u n d s . 5us be seen that the A r a b s are in their Summer quarters d u r i n g nmer and autumn malaria seasons, and it may, therefore, be according to the malarious nature of the c a m p i n g g r o u n d s so amongst them vary. T h e majority, as they c a m p either on the ~r Zab, or desert reaches of the K h a s a and T a u k Chai, where tes are low or nil, m a y be expected to show v e r y little malaria or low spleen rates. On the o t h e r hand, the smaller sections p near the outer fringe of villages where the spleen rate is fairly 71 per cent., l e d a i d a 90 per cent., T o b u s a w a 33 per cent., per cent., Hissar A h m e t Beg 75 per cent., all 1 kariz water), m a y show more malaria a n d fairly h i g h As the t a k i n g of the spleen rate in A r a b camps is :rather a formidable undertaking, r e q u i r i n g more time than in the :settled villages, it was only attempted on a few occasions, but the few examinations done s u p p o r t what has been said. T w o camps near Yaichi showed spleen rates of 50 per cent. a n d 17 per cent. respectively, and one camp near Hissar A h m e t B e g 33 per cent. 5.

A SHORT NOTE ON THE PARASITE RATE.

The rarity of occasions, d u r i n g 1923, on which one has found parasites even in children d u r i n g the malaria season, unless the patient was suffering a t the time from fairly definite malaria, p o i n t e d to a low parasite rate among the children. T h i s was s u p p o r t e d by an examination of children made on one occasion. O n 31st October blood smears were taken from twenty-seven native scholars in the Kurdisl'] village of K a r a H a s s a n . T h e village is noted for its unhealthiness and has a spleen rate of 100 per cent., all the twentySeven pupils s h o w i n g e n l a r g e d spleens, while a random examination of about the same number of children in the village about two months previously bad given the same result. E x a m i n a t i o n of thin films showed the presence

5~

MALARIA IN N O R T H E R N MESOPOTAMIA.

of parasites in two of the boys, one of whom gave the history of fever f0{ the previous three days. T h i s boy showed a few undefined rings in h~ blood while the other showed a quartan infection. W h i l e such an examina tion is insufficient in itself for definite conclusions, it confirms the impressio~ that, at least d u r i n g 1923, the parasite rate in indigenous children, even in hyperendemic areas, was a very low one. T h e same impression has been received with regard to adults, in hyperendemic areas, in whom enlarged spleens are also common and who often seem to show a comparatively high spleen rate. J u d g i n g from the difficulty of finding parasites in the blood of such people unless suffering from actual fever, this comparatively h i g h adult spleen rate also seems to be accompanied by a low parasite rate. 6.

THE SPLEEN RATE.

T w o sets of statistics are herewith given. ( a ) THE SPLEEN RATE OF K I R K U K TOWN ACCORDING TO MOHALLAS OR QUARTERS.

These figures were compiled from the examination of chiJdren in the government and mosque schools in F e b r u a r y and March, 1923. T w o points are worthy of notice. 1. T h e r e is a marked variation in the spleen rate of the mohallas or quarters of the town, r a n g i n g from 22 per cent. to 100 per cent, a n d in each case the variation can be explained b y the existence of malarial conditions. Thus, Shaturlu, which has a spleen rate of 100 per cent. (the number of children available for examination in this mohalla was unfortunately small but it is certain that the spleen rate is a very high one), is traversed by several main water channels besides being" situated near the river bed wl-~ich, though almost dry in summer, yet contains weedy pools under its banks. Houses alternate with gardens, whiIe m a n y of the houses themselves contain r u n n i n g water and small gardens. Tile Christian quarter, which has a spleen rate of 22 per cent., is situated on the top of a large mound or K a l ' a and has no vegetation or water. T h e other mohallas have spleen rates l y i n g between these two figures, which correspond more or less with the existence of conditions favourable to the occurrence of malaria. W h e n one has grasped the fact that such variation can exist in a town ,which measures less than two miles across, one is no longer surprised when adjacent villages are met with which show marked variation in the spleen rate or in the occurrence of malaria. 2. The spleen rate which concerns us most is that of the age group two to ten years. But the rate of the age g r o u p ten to fifteen years and that of fifteen to twenty years has also been given. T h i s indicates the steady diminution of the spleen rate with age.

MALARIA IN NORTHERN MESOPOTAMIA,

(b)

T H E SPLEEN

RATE O F T H E

KIRKUK

59

DIVISION.

ires were compiled from the examination of school children :owns and villages where schools existed (about ten places ildrdn of the various villages visited on tour. T h e g r e a t !ages were of small size and one had, therefore, to be satisfied all numbers of children in each place. A s it would occupy :e the spleen rate for each vii[age is not detailed, massed ~ing given. T h e Division has been divided up into conaccording to the spleen rate, utilising, as far as possible, s, such as rivers and hill ranges, as boundaries. In some ~as correspond to existing political sub-divisions, in other not. Variation in the spleen rate of adjacent villages has to a certain extent, although, on the whole, such variation d to the east of the Q u a r a g h a n - - K i f r i - - T u z - - T a u k - - T a z a - K e u p r i road, where conditions are more u n i f o r m l y malarious. bably because it follows tide foothills, forms, on the whole, !a surprisingly accurate d i v i d i n g line, most of the villages to the east, or ;hilly side, showing high. spleen rates, while those to the west, or desert side, show moderate spleen rates p a s s i n g to low a n d nil the further one goes into the desert. This road, at the same time, serves as a r o u g h ethnological line of division, the m a j o r i t y of people to the east side b e i n g K u r d s a n d the majority to the desert side b e i n g Arabs, although the K u r d s have encroached in a good many places. The a c c o m p a n y i n g tables and m a p give the spleen rate a c c o r d i n g to districts. In addition to w o r k i n g out the spleen rate according to districts, all villages have been r e g r o u p e d according to their spleen rate, those, for example, with spleen rates between 50 and 60 b e i n g put into one class a n d so on. It was intended from this r e g r o u p i n g to work out the splenic indices3 such as the " s p l e n " and the " a v e r a g e e n l a r g e d s p l e e n " but it is doubtful whether the c o m b i n e d figures, consisting of massed results from vilIages, in the great m a j o r i t y of which not more than ten to twenty children were available for examination, wouId be sufficiently accurate for tide purpose. A point of much interest raised bv CHRISTOPHERS and SHORTT in their "Malaria in M e s o p o t a m i a " was the fact that they found the " s p l e n " of Mesopotamia greater than that of India, the former a v e r a g i n g 114 g r a m s and the latter 90 g r a m s . T h e " s p l e n , " according to CHRISTOPHERS, is " t h e mean increase in splenic substance resulting from a single infection in a child 2 to 10 years of age. ~' By this is meant an untreated infection as distinct from a mere attack or the condition under treatment. It can be calculated from the spleen rate b y the means of formulae. Calculations made from the a c c o m p a n y i n g figures support, as far as Northern Mesopotamia is

60

M A L A R I A IN N O R T H E R N

KIRKUK

MESOPOTAMIA.

TOWN.

DETAILS OF SPLEEN RATE OF MOHALI.AS, Ages 10 to i5

Ages 2 to 10 No.

No.

Per cent.

Exam - with ined. Spleen

No.

No.

Ages 15 to 20

No. No. Exam- with ined. Spleen

Per cent.

E~:am- with

ined. Spleen

9 14 57 36

9 11 33 8

lO0 78-6 57.9 22.2

15 23 49 11

13 13 15 2

43 49 14 21 20 34 90

24 36 8 ]4

51 21 18 20

8

55.8 73-5 57.2 66.7 40,0

12

35.3

71

78.9

43 34

[ 27 26 23 8 4 17 30

234

60.5

295

148

50.2

98

86.7

8

56.5

4

30-6 18.2

][O --

33.3 76-2

24 26

72.2

3

80.0 20,0 39.6 88-2

4 7 21 2

Mohalla or Quarter.

Per

cent.

7 2 4

87.5 50.0 40.0

6

25.0

25 2 4 I ~ . [I

57.7 33'3 100 28-6 27-3

Shatudu ' Begler Sari Kahia C h r i s t i a n Quarter, Kal'a

20

KIRKUK

i

45

Rest of Kal'a Akhir Hussain Bullakh Piriadi Chukur and Auchi Musullah and Chai Jews' Quarter

Totals.

45-9

TOWN.

SPLEENS CLASSIFIED ACCORDING TO SIZE.

1__

Ages 2 to 10. Finger-breadths 0

1 ?2 i2 15

28j 19t13 13~12

i

1

5 6

-

-

22 / 8

~

-

°t

1

2

3

4

5

~: o ~

Finger-breadths below umbilicus, 0

3~ 2 1 __l-16

7 8

3 3

1 4

2 -

2

-

-

-

-

8 0

5 1

1 1

3

:ti I:

35

21

24

-2

7 1

_

12 8

29t 0,51

Finger-breadths

5

9

5

1

2

6

5

2

4

2 I

lri

Quarter.

Ages 15 to 20.

Ages 10 to 15.

2

1

2

3

1;12 5

t--~-ll[!

4

1

- 2_I

10

7

~: o 5

Shaturlu Regler Sari Kahia (Kal'a) Christian Qtr. Rest of Kal'a Akhir Hussain Bullakh Piriadi Chukur and Auchi iVlusallah and Chai Jews' Quarter, Totals.

MALARIA IN NORTHERN MESOPOTAMIA.

61

SPLEEN RATE OF KIRKUK LEWA, Total [ No. with [ Spleen C h i l d r e n . t Spleen I Rate.

AI~EA. on K u p r i area ......... Ld T e l All area .. s o u t h - w e s t of Kirkui£ f r o m "Fathai~ T a u k Chai . . . . . . . . . . . . ~d K a r a H a s s a n area ...... w e s t of T u z - T a u k r o a d ...... L. U. p.p e. r . T. u .z . Chai . . . area . . .a n.d . D. e s. h t - i -

i'Zc~g£g'~targ~ . . . . . . . . . .

VA.

SPLEENS

CLASSIFIED

/ ]

353 147

l t

35.8

819 394 187 156

[ ~ [ j|

404 314 67 91

[ ) | ]/

49"3 79-7 35.8 58-3

19

!

7~

......... . . . . . . . . . . . . . . .

ea

410 410

j

/

439 255

~

ACCORDING

336

61/

t

t

1

4i Total

2

44 47 79 30

194

32

7

...

85 12 27

°!

103

Vmb.

Below Umb.

10

2

12

12 4 1

5 56 14 48 63 10

76.5

4

-6

302

- ~-~-6

5: 95 3O

18 63 52 14 14

11

7 5

8 9

3 ¸

257

23.9

TO SIZE.

Finger-breadths i

]

86.1

407

29

DETAILS OF SIZE OF SPLEENS. VILLAGES GROUPED ACCORDING TO SPLEEN RATE. Finger-breadths

Spleen rate Groups.

0 I to lO v e t ;;i,t. II to 20 ,, ,, 21 to 30 ,, ,, 31 to 40 ,, ,, 41 to 60 ,, ,, 5i to 60 ,, ,, 31 to 70 ,, ,, 71 to 80 ,, ,, ~1 to 90 ,, ,, )l t o l 0 0 . . . . {irkuk T o w n .

1 74 99 203 233 176 152 52 70 60 60 20 153

6 15 23 35 25 13 17 20 33 18 105

2

3

i! --

1 9 21 14 21 12 25 41 52

45

V m ] Belc w biliUm cus. bHic as

4 7 19 23 11 29 28 68 77 36

10 19 15 24 19 38 48 99 110 1 25

2 1 7 9 20 8 24 32 74 78 22

2 2 5 7 7 7 19 56 86

I-

Child'n Examined.

No. with Spice

---

74 108

-9

-2 1 3 1 --7 14 1

244 314 274 275 123 210 248 449 438 387

41 81 98 123 71 140 188 389 418 234

T h e figures for K i r k u k t o w n h a v e b e e n g i v e n separately. T h e y w e r e t h e first s aleen r a t e observations to be m a d e , a n d an o l d e r m e t h o d o f classification was u s e d ( h a n d s b r e a d t h a n d u m bilical spleens b e i n g i n c l u d e d in one class). F o r all later spleen rates t h e full classification w a s adopted.

~2

MALARIA

IN

NORTHERN

MESOI'OTAMIA.

%,, ,

e

t

¢

.... ..~

s,

%

t

i

t

z

o V-.c

¢C J

X:

•

c

63

MALARIA IN NORTHERN MESOPOTAMIA.

Alton Kuprl Area (I)

86.1y. Khasa Chal

Area (2 35.8

Are'a (4) Area (3) Taza

Tuz ~

-Area (6)

Area ( 5 ) ~ 58,3% 35,8% Tgz Khu rmat.u..X. / - ~ ' "

Area (8)

SPLEEN RATE, KIRKUK LEWA, 1923 •

Area (9) \ 23,9%

~4

MALARIA IN NORTHERN MESOPOTAMIA.

concerned, the observation that the " s p l e n " is more than 90 grams, afi~ would indicate that the difference is even greater than that found ~ CHRISTOPHERS and S H O R T T . The formula r =

2--1og(100--S) "00436 was used, where r is the number oflil

"splens" distributed and S the spleen rate. The mettiod of calculation ~as~ followed as demonstrated in "Malaria in Mesopotamia ''2 and the weigt~tlI of the " s p l e n " found by dividing the total increase in splenic substance: by r. The weight of each degree of enlargement of the spleen was take~: as given in BYAM and ARCHIBALD'S "Practice of Medicine in the Tropics," except that the weight of a spleen enlarged below the umbilicus was taken as 850 grams. Taking the average of " s p l e n " values of each spleen rate group the " s p l e n " works out at 175 grains. This result is not ~ strictly comparable, however, with that of CHRISTOPHERS and SHORTT, as at that time a lower scale of weight was applied to the larger size of spleens, which would make the difference seem more marked than it really is. As already mentioned, this result cannot be regarded as absolutely accurate for various reasons, a m o n g which may be mentioned the small number of children available for examination in the majority of villages, the tendency for children with large spleens to submit themselves more readily for examination, etc. But as it was the best that could be done under the circumstances, the figures are here given. But even although these figures may not be quite accurate, the difference is sufficiently great to indicate that the average malarial infection in these parts gives rise to a markedly greater splenic enlargement than is usually recorded from other areas with similar climatic conditions. There is no doubt that, from a clinical point of view, ttiis, viz., the great enlargement of the spleen one meets with in children, and also often in adults, is a striking feature of the malaria in this neighbourfiood, and the higti value of the " s p l e n " points a way to a possible explanation. It has already been explained how quartan malaria seems a common and widespread infection. It might reasonably be expected ttiat the chronic nature of this infection will lead to a much greater splenic enlargement than will result from the shorter-lived benign and malignant tertian infections. Such an observation has already been made by Sir LEONARD ROaERS 4 who, from a series of cases in India, found that the splenic enlargement of benign tertian was greater than that of malignant tertian, and that of quartan malaria greater than both. I would, therefore, suggest that a very possible explanation of the comparatively great splenic enlargement in Northern Mesopotamia is the prevalence of quartan malaria. An item of interest with regard to the Q a r a T a p p a district (area No. 9), is the fact t h a t in the scheme, at present under consideration, of damming

MALARIA IN NORTHERN MESOPOTAMIA.

65

~ l a h River at the Jebal Hamrin, to store water for irrigation of the ~ o the south and west, this area will be more or less flooded. If this bout, it will be interesting to note what change may take place in ~leen rate.of the unflooded villages round about. ~}fore passing from the subject of spleen rates, it must be mentioned condition of splenomegaly with hepatic enlargement has not infre~ : ~ y . been met with in children and adults in the Kirkuk Lewa. This con~ts perhaps commonest in malarious villages, where a certain number of at least are due to malaria, but is also met with in areas with little ~ria where it almost certainly is not due to this cause. There seems to a resemblance, clinically at least, between some of these cases and ~ptian splenomegaly, and they probably represent an early stage of what ns fairly common in most parts of Iraq, viz., the cases of hepatic hosis and splenomegaly with terminal ascites, which are admitted to spiral to die. These cases, however, do not seem to be sufficiently }mmon to interfere seriously with the spleen rate as a measurement of ialaria, although more than once it has been confusing to find, in a village ith a low or moderate spleen rate, a child with an enlarged liver and a ~pleen perhaps reaching midway between the umbilicus and pubis.

~

7.

METEOROLOGICAL CONDITIONS AND THEIR RELATION TO THE MALARIA SEASONS.

A. graph is given of the 8 a.m. relative humidity and the monthly mean maximum, minimum and 8 a.m. temperature from July to December, compiled, with the kind permission of the Royal Air Force, from the figures of the R . A . F . meteorological station in Kirkuk. The malaria season and the time of increased mosquito breeding have been marked Underneath. Of the climatic factors influencing the endemic prevalence of malaria, the two most important are temperature and humidity. It seems definitely established that a mean daily temperature of above 60°F. is necessary for the propagation of malaria. If, therefore, a line is drawn on the graph at the 60 ° level, the period intervening between the date of the rise of the 8 a.m. temperature graph above this line a n d the fall beIow it, should be favourable, from the point of view of temperature conditions, to malarial infectivity. This period will be seen to extend from the middle of April to the beginning of November. With regard to humidity, the importance of this factor has been shown by GILL5 in dealing with malaria at very high altitudes. He brings evidence to show that though the temperature at these altitudes may be favourable for quite a long time, yet, unless in addition a mean relative humidity of over 68 per cent. (8 a.m. readings) is present, transmission of malaria

~6

MALARIA IN NORTHERN MESOPOTAMIA,

will not occur. It has also been sometimes advanced that ordinarily a mean relative humidity of about this figure, in addition to a favourable temperature, is necessary for malarial propagation. E x a m i n i n g the graph from this point of view one finds that if this were so there should be ;very little malaria in Kirkuk, the time of favourable temperature coinciding more or less accurately with the presumably unfavourable humidity. This , and the MONTHLY MEANGRAPHOF TEMPERATUREAND 8 ^.,~. RELATIVEHUMIDITy.

K1RKUK, 1923.

gaX, T~P.

110

100

100,

90"

80

~

80-

'~0 ~

~

70"

Z

~0-

60 ~

_

/

.2 <

30

~

~'e,

30

20

20

10

!0

o

0 ~PRl'--I." ~ A V

.'.':.--'-'..'-"

'jbNE

'iUU~

~---U-~V-~-~-EPT.' oCTI ' NOV, ~

.

MARKED |NCREAS~ 0 6 M O S Q U I T O L RF.,F£31NG MALARIA SEASON

mere fact that fresh infections were a t3P earin g,- in l~u n e and l'ulv, ~ ~ ~ when t hi-~ relative humidity was as low as 40 per cent. a n a 30 per cent., is sufficient show that, as far as Northern Iraq is concerned, the main malaria seaso.~ is as,ssociated with a very low relative humidity, a n d tha t a high degree ~ humidity, usually looked upon as a necessary accompaniment of m a l a r ~ prevalence, is absent as a climatic factor.

MALARIA IN NORTHERN MESOPOTAMIA.

6'~

It has just been mentioned that temperature conditions commenced to be favourable from the middle of April. W h y , then, did malaria not start definitely at that time and why did it stop in A u g u s t ? R e a s o n s for not starting m a y be one or other of the following. (1) It m a y be that a considerably higher temperature than 60°F. is necessary for malaria p r o p a g a t i o n in these parts. T h a t this is not altogether the case is shown l~y the fact that d u r i n g late October and early November, when fresh infections were appearing, tile temperature was not much, if at all, above 60°F. (2) T h e increased mosquito breeding which preceded the s u m m e r malaria season ~carcely seems accidental and without m e a n i n g . T h e most likely e x p l a n a tion would be that most of the m a l a r i a - c a r r y i n g mosquitoes had been killed off d u r i n g the winter and that, until fresh adults had hatched out, fresh malarial infections would not take place to a n y great extent. T h e sequence would then seem to be (a) favourable temperature, (b) b r e e d i n g of malaria carriers, (c) occurrence of malaria. In this case the lengtli of time required for the mosquito to hatch out, acquire power to impart infection, in addition to the incubation period of the h u m a n infection, would explain the long delay. Infection ceased in A u g u s t , p r o b a b l y because bf the combined effect of continued high temperature a n d low humidity. It is doubtful if dessication of breeding-places p l a y e d a great part in the cessation of infection, as breeding-places seemed not less plentiful than in October, when fresh infections again b e g a n to occur, no rain h a v i n g meanwhile fallen. It might be expected, also, that the s u m m e r malaria season should start in the southern and low-lying districts first, since favourable conditions o f temperature will here first be met with, while the contrary should be t h e case with the late autumn season, the more elevated and northerly districts being the first to cool down to suitable temperature conditions. CONCLUSION.

. For the proper u n d e r s t a n d i n g of malaria and malarial manifestations In such a place as K i r k u k , situated in sub-tropical foothills, observations over a period of several years seem necessary, including, preferpidemic or bad fever year with the subsequent year or two years. ecially necessary in view of the fact that such a chronic infection Le to the qnartan parasite seems common. ;everity of malarial fever seems to v a r y very much from year to n-immune bodies of people, such as pilgrims, refugees or troops, ~ome years, when infections are mild, to be able to move about, rithout due precautions, in malarious areas even in the malaria ithout being u n d u l y infected, while in an epidemic or bad fever a proceeding might result in a serious catastrophe. From a oint of view the s u m m e r malaria season is specially to be g u a r d e d _

I'~tALARIA IN NORTHERN MESOPOTAMIA.

against, although, as already shown, the a u t u m n malaria season can, as in 1918, be a Very severe one. SUMMARY.

T h e following are the main features which have been noticed during 1923 with regard to malaria in ti~e K i r k u k Division of Northern Mesopotamia in dealing with indigenous natives. Treatment and preventive measures are not touched upon. 1. There were two malaria seasons, the main one in the summer and a lesser one in the late a u t u m n . (a) T h e summer malaria season lasted roughly from the beginn i n g of June to the middle of A u g u s t . It was caused by the malignant tertian, and to a less extent b y the b e n i g n tertian, parasite. (b) The a u t u m n malaria season occurred in late October and November, b e i n g most marked in the first half of the latter month. It was due to the m a l i g n a n t tertian parasite. 2. Malaria in 1923 showed certain features which were the outcome of malaria in the preceding summer, when it was prevalent in epidemic form. The chief feature was the marked prevalence and predominance of residual quartan malaria, which existed d u r i n g the first five months of the year until the starting of the malaria season. 3. It is judged that normally quartan malaria is a comparatively common infection, and that a fuller explanation of the marked quartan predominance referred to is that it was due to residual infections from an epidemic year occurring in an area where quartan is peculiarly common. Quartan malaria was not confined to a n y one part of the division but was equally prevalent everywhere. 4. M a l i g n a n t tertian was the main cause of the summer a n d autumn malaria seasons. Infections started somewhat later than the b e n i g n form (roughly fifteen days) and rapidly disappeared with the p a s s i n g of the malaria season. Crescent infections were comparatively not common. T h e main clinical manifestation was a quotidian fever of no great severity. Pernicious forms were absent. Benign tertian was the earliest infection to appear in a n y n u m b e r with the o p e n i n g of the malaria season. This parasite seemed to depart markedly from its usual r61e as a cause of relapses, its lbehaviour as regards disappearance of infection at the end of the malaria season closely resembling that of m a l i g n a n t tertian. There was no evidence that b e n i g n tertian was a factor in the a u t u m n malaria season. Quartan malaria. Presumably its season of infectivity coincided with the summer malaria season. This, however, could not he proved, fresh cases being obscured by the mass of already existing quartan malaria. Triple infections were comparatively.common, especially in the early months.

MALAI-IIA IN NORTHERN MESOPOTAMIA.

69

Double infections not common. Quartan malaria, as met with, has quite sustained its reputation as the cause of an extremely chronic infection. 5. Nomadic Arabs on the whole suffer very little from malaria. Its occurrence can be explained b y their habits. D u r i n g both the s u m m e r a n d ;autumn malaria season they are in fixed c a m p i n g grounds, a n d according to the malarious nature of these g r o u n d s so will malaria a m o n g t h e m v a r y . Malaria was most seen in small sections which camped alongside the f r i n g e of villages on the edge of the desert, to the west of K i r k u k a n d T a z a Khurmatu. 6. The Q u a r a g h a n Kifri - - Tuz - - T a u k - - T a z a - - K i r k u k - - A l t o n Keupri road serves as a r o u g h line of division of malarial endemicity. O n the east, or hilly side, malaria is hyperendemic and shows very h i g h spleen rates. T h e area to the west or desert side shows m e d i u m spleen rates, passing to low or nil the further one goes into tile desert. 7. M a l a r i a in the K i r k u k Division seems to be associated w i t h (a) A higher degree of spIenic enlargement than ttiat usually recorded. (b) V e r y high spleen rates a m o n g the children a n d often a comparatively high spleen rate in adults. (e) A s u r p r i s i n g l y low parasite rate in children a n d adults considering the high spleen rate. The theory is advanced that (a) is due to the prevalence of quartan malaria. It is possible that this fact also contributes to (b) a n d (c). 8. Each malaria season was preceded b y a marked increase of mosquito breeding, including Anopheles. 9. A feature of the main m a l a r i a season was the fact that it lasted throughout the hottest and dryest month of the year, when the 8 a . m . mean temperature was about 90°F. a n d the mean relative h u m i d i t y was below 30 per cent. H u m i d i t y , within limits, appeared to be a factor of comparatively little importance in influencing malarial prevalence. ~

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~CKNO WLEDGMENT.

T h a n k s are due to Mr. B. C. Newland, Director of Surveys, B a g h d a d , f o r preparation of the two maps. 1. 2. I 3. 4. 5.

BYaM riND ARCmBALD. "" Practice o] Medicine in the Tropics." CHalSa-Oprl~a, S. R., and Stlo~'rT, H . E. J a n u a r y , 1921. " Malaria in M e s o p o t a r a i a , " Indian JournM o] Medica~ Research. Vol. viii, p. 59~. C~tS~'C~P~ERS, S . R . April, I915. " The Spleen Rate and other Splenic Indices." Indian ]ourna~ of Medical Research. Vol, ii, p. 823. RooeRs, L. " F e v e r s in the "~roplcs." G~L~., C. A. October, 1923. " T h e Relation of Malaria to Altitudes." I~dian Journat o~ Medical Research, Vol. xi, p. 511.