470 



NATURE 



[September 20, 1923 



Letters to the Editor. 



The Editor does not hold J:: 

 of>inions expressed by his cc- 



In 



Jed for 



'■'>f!--e is 



I h' I u| uf Miliaria in ttie Malay i'ctiinsiila. 



!' ■■ ' ' ! ' ''^ cporli iiiakiiii^ (li 

 prnMcni in mcilii : 



ii.> >.>,.^>, w, ,,,.,,.,.,,, ,,,. secret 111 \,ltU!i 



cunningly liid th.m llie inal.tria sec ret. .M.'.l.ina 

 known to he (.onucclcil willi su.iiiips, ami t" .■ 

 reducecl by drainage and cullivalinn \r\, as it 

 nicrcK- (() confuse, men found lliat lu lluod .some 

 ■ lii.ilK improved iieiit!:; and elsewhere 

 II Miayc and the culti\ at Kill (il the soil produced 



the most serious and di \astating outbursts of the 

 disease. Yet again, malaria was found not only in 

 swamps, but also often on hills and dry sandy deserts. 

 Some jungle-covered land was singularly free from 

 malaria : other jungle land was intensely malarial. 

 In fact, malaria existed on soils of every conceivable 

 variety, of every age in geological time. It was 

 impossible to point to any mineral, chemical, or 

 vegetable condition essential to its presence. It was, 

 and had been for hundreds of years, a dark, inscrutable 

 mystery. 



Sir Ronald Ross's genius changed darkness to light, 

 and inaugurated a new era in tropical colonisation. 

 To many, of course, the discovery that malaria was 

 carried by mosquitoes merely confirmed them in 

 their pessimism that the control of malaria was beyond 

 human effort. They were wrong ; and briefly I give 

 two examples of what has been done in the Malay 

 Peninsula in the past twenty years under different 

 physical conditions. I would premise that the places 

 of which I speak are within three degrees of the 

 equator, have a rainfall round about loo inches a year 

 spread throughout the year, that the country as a 

 whole is naturally covered by an ever-green damp 

 jungle, and that mosquitoes exist in myriads at all 

 times. One example is of malaria on low-lying land ; 

 the other of malaria on hill land. 



Carey Island. 



Twenty years ago or less, if the tropical sanitarian 

 had been asked what was the class of land least likely 

 ever to be freed from malaria by the control of 

 mosquitoes (or by any other means for that matter), he 

 would unhesitatingly have named the low-lying coastal 

 land, with high ground- water, heavy clay soil, liable 

 to flooding from the sea. He could easily have 

 justified his choice. Such land had ever been known 

 to be pestilential almost beyond description ; it had 

 given rise to innumerable speculations on the cause 

 of malaria — the decay of coral, the mixing of fresh 

 and salt water, to name but two. In every part of 

 the tropical world examples of the deadly power of 

 malaria in coastal regions could be given. In the 

 Malay Peninsula and Archipelago, for example, the 

 Governor, Sir Frank Swettenham, in 1901 ordered 

 the new port called after himself to be closed, so 

 overpowering was the malaria. On the opposite side 

 of the Straits of Malacca, the port Belawan in Sumatra 

 was so malarial that the Dutch left it ever\ night, 

 retired to a town some twenty miles inland, to return 

 by the first train the following morning. Many other 

 examples could be given. 



Carey Island is situated on the coastal belt of such 

 land. It is, indeed, an island just above sea-level in 



NO. 2813, VOL. 1 12] 



•en. In 

 se, both 



its luRhest part.s. an<l obviously has been formed b\ 

 the alluvium from the hills, ^urrounde*! by water, 

 one .side by i] .a others by large fivtr- • 



< rine estuari* ing salt water, it is frii ■ i 



uy mangrove su .veretl by den 



jungle. ThrouMi / Ij and bread 1 



swamp, cither of iiesu wai«-r or salt. 



In i<(0'., a pioneer planter of .Malaya, the lat< 



Mr. 1",. \'. Ciarcy, tcxjk '■■• ■ ■ ion of 30,000 acres 



on the island and h> mg of rubber an<l 



(oi omds. The islaii led and -)•■■"—! 



vere necessary, luiough was i 

 '<i malaria Id ena])U; the labour Ic. ... 



' ^toin ni t, and opening raj 



1 ceded. i <xx) acres (or n.i. 



-" sipiare miles) are under cultivation. No 1 



(j1 a population of from 20 to ;^o- has ci 

 malaria on the island sinc< In njn ihc 



average Asiatic population u ., I here were 



26 cases ' nical ca.scs, and IJ 



parasitf .1 is is a rate of 6 ; 



The lowest rate rerordcd m Panama wa ;;.■ 



There were at the end of last vear o<k ., .,1 



whom or 0-9 per cent, had ' ' 

 about ,dl, liut not ahsolutei 



adult anti child, there is reason {> , ;.eiie\e me infection 

 had been contracted elsewhere Steps are now be:!!;; 

 taken to end the last possible .source of malaria, 

 naimiy the disused and neglected wells in the sm all 

 pruate gardens of the coolies. When these arc 

 properly supervised, I am convinced malaria con- 

 tracted on the island will be as unknown as malaria 

 contracted in th. ,i London. The death-rate 



of the labour for. ,zz was 8-2 per mille. 1 his 



freedom from malaria has been achieved by gocnl 

 drainage and by the selection of suitable sites for 

 l)iiildin.<,'s. It costs the Estate practically nothing ; 

 wiiile the absence of malaria makes the Estate one 

 of the cheapest producers of both rubber and coconuts 

 in the East. This is an example of the control of 

 malaria carried by two species of anopheles, namely 

 A. umbrosiis and A. Ludloivi. 



The City of Singapore. 



Following the control of malaria in the coastal 

 regions, a new and apparently even more difficult 

 problem confronted us, namely, malaria on hill land. 

 In the ravines or valleys, when under jungle, malaria 

 was carried by Aiiopluhs i(»!!')'-'>i<s ; when the jungle 

 was swept away, when, for stagnant swamps in the 

 valleys, swift clean running streams were substituted, 

 malaria was of even greater intensity ; in many places 

 death claiming over 300 out of every 1000 of the 

 population per annum. The mosquito carrier which 

 lived in these streams \va-~ . macidatus. It is 



not my purpose here to di: arious methods by 



which this malaria has been r^ucccssfully controlled, 

 even in small rural areas ; it has been done at a cost 

 well within the reach of a commercial undertaking ; 

 indeed the money spent has been recovered within a 

 short period by the greater efficiency of the labour 

 and a lowered cost of production. 



I prefer rather to speak of the ex' ■•"•^"' '■ ork done 

 in the city of Singapore. Prior t malaria 



wave swept over the citv almn-^r e\ _-. . ._,.;. As will 

 be seen from the chart d generally reached 



its maximum in the mom: \ . In 191 1 I wjis 



asked to advise the anti-maiana committee, and 

 drew up plans for the control of malaria in a selected 

 area. The late Dr. W. R. C. Middleton was then 

 Health Officer. For the first two years Dr. Finlayson 

 was seconded for the super\ision of the work, which 

 was carried out by Mr. McGee, the engineer engaged 



