SUPPLEMENT
TO THE
Hongkong Weekly
શ્
AND
SUPREM
E
COURT
Stress
China Oderland Trave Report.
THE MOSQUITO AND MALARIAL FEVER.
HONGKONG, SATURDAY, 20TH DECEMBER, 1902.
LECTURE BY DR. J. C. THOMSON
AT THE CITY HALL.
On Monday evening, the 15th inst., Dr. J. C. Thomson lectured under the auspices of the Odd Volumes Society on the mosquito and its relation to malaria. There was a large at tendance, including many, ladies. H.E. the Governor, Sir Henry A Blake, G.C.MG, presided; and among others present were Lady Blake and Miss Blake, Sir Johu Keane. Private Secretary, and Captain Ar- buthnot. A.D.C. to His Excellency; H.E. Major General Sr William J. Gascoigne, K.C.M.G., Lady Gascoigne, and Captain the Hon H. W. Trefusis, A.D.C. to His Excellency; Sir William M. Goodman, Chief Justice, and Lady Goodman ; Commodore Robinson and Mrs. Robinson and Mr. H. E. Pollock, K.C., hon. secretary of the Odd Volumes Society,
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inalaria," was that bad air, evil vapours, noxious exhalations from damp or marshy soil, were the cause of this the source above all others of mortality and ill-health in the tro- pics and sub-tropics. Within the past few years, however, our knowledge on this subject has been revolutionised; and we now know as a matter of demonstration. conducted under the most stringent conditions of scientific investi- gation, that a certain genus of mosquito, the anopheles, is the principal, and probably the only, carrier of malaria from one human being to another.
may say to-night will chiefly incriminate!“ the genus anopheles, the crusade I preach is, for reasons which I shall briefly indicate later. a
war of extermination against the whole family of mosquit es in all its bran- ches.
use the word "extermination deliberately, even while I know it to be on the wide scale an impossibility. Mosquitoes are world-wide in their distribution. They equally affect great centres of population and the wildest wastes on the face of the earth; they are equally the scourge of the Arctic explorer aud the terror of the tropical traveller; they are found on the hill-tops of the world, and they swarm throughout its river deltas; and the same species of mosquito has been found at an altitude of 13,040 feet among the Himalayas and on the sea-level in Scandinavia. And the fecundity of the insect is amazing. Ficalbi says that one mother mosquito may in the fifth generation be the progenitor of twenty milliards. Howard shows that one rain-water barrel may contain nearly 20,000 larvae, and that they may produce twelve generations in
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Let me remark in passing that while the word "mosquito" is a diminutive of a Spanish and Portuguese word mosca a fly, and culez is the ordinary Latin word for a mosquito or gnat, anopheles is a transliteration of a Greek adjec tive signifying "harmful" or "injuricus." " had the Surely he who named "anopheles vision of a seer!
The malaria parasite was first recognised as such in 180 by a young French surgeon, still living, named Laveran, at that time stationed at Algiers in North Africa. Examining under the microscope the blood of a malaria patient quitoes expressed by 25 figures, an unthinkable he saw certain organisms within the red blood Eumber. In Hongkong, mosquitoes are found cells. which on further research proved to be everywhere throughout the island, from the Flag-constantly present in all simila cases. staff to the Praya. They breed in myriads in every rarine throughout the length and breadth and height of it. How then propose mination ?"
This is
what he saw. The blood consists of a liquid in which float enormous numbers of little inde- *exter-pendent bodies, so minute that a cube of blood 1/25th of an inch across contains over five millions of them. These cells are of two kinds, white and red, the red greatly preponderating. and it is within these minute ed corpuscles that the malaria parasite has its habitat, and It feeds on the undergoes its development. red colouring matter of the cell, destroying the cell itself in the process. Most of the parasites as they develop are transformed into little mass-s of spores, which by the rupture of the containing blood cells are set free in the blood-
one suminer. This at a low estimate would HIS EXCELLENCY THE GOVERNOR, in intro-produce in a single summer a number of mos- ducing the lecturer, expressed the pleasure it gave him to preside at that the first of the season's meetings of the Odd Volumes Society, meetings which had been very interesting in past years and which had been resuscitated thanks to the energy of Mr. Pollock, recently returned to the Colony. We had in Hongkong immeasurable possibilities for every kind of Over against the facts I have just mentioned, game conceivable for the purpose of improving we have the fortunate circumstance that mos- our physical condition and keeping ourselves in quitoes as a rule fly only a very short distance healthy but there had been with few exceptions from their native haunts, from the place where no intellectual movements in which the com-
they were bred. They take shelter from the munity could take part and where subjects of gentlest breeze, and are hence rarely carried interest might be discussed. In connection any distance by the wind. The distance of with the Odd Volumes Society there had been flight has been variously estimated by different many interesting papers read from time to time, observers, and while some make it a few hùn- but no subject had been of more interest, dred yards, and others think they may at times locally and generally, than the subject on which fly half a mile or more, all agree that it is very Dr. Thomson was going to address them that limited. For safety let the longest estimate be night the subject of mosquitoes with reference accepted. The breeding habits of the mosquito to malarial fever, which was the curse of life in are well ascertained and easily assailable, and the tropics and one which we felt a great deal in what I claim is that we may create in Hong- Hongkong. He would only say that at the end kong and its immediate neighbourhood condi of Dr. Thomson's lecture they would be very tions that will make it impossible for the insect glad if any gentleman present would join in dis- to breed within the City of Victoria; so that, while cussion and offer any observations which struck, an occasional mosquito might continue to find its him with reference to the matter to be brought way from the outlying districts, the mosquito before them. He had no doubt that some of may in this city become for all practical General Gascoigne's officers of the Royal Army purposes as extinct as the dodo; and, so far as Medical Corps, who had a particular knowledge infection with malaria within the city itself is of the subject, of the influence of the mos-concerned, this City of Victoria may become quito in spreading malarial fever and whether it was the only source from which the fever was spread, would be able to give them some very interesting information, which would be very glady listened to. In conclusion His Excellency formally introduced Dr. Thomson to the audience,
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Dr. THOMSON said-Your Excellency, I very willingly consented to the proposal that at the opening meeting of this session of the Odd Volumes Society I should lecture on the subject of the relationship that exists between malaria and the mosquito, affording me as it does an opportunity of disseminating information on a subject than which there is none more impor- tant to the public health of this Colony (with the possible single exception of bubonic plague), which may lead to co-operation in measures for the destruction of the cause of this disease so far reachin in its effects on health and life. And -let me say forthwith, that, while what
as free from malaria as is the city of Rome, which, built as it is in the midst of a region full of the most pernicious forms of malaria, is yet itself quite free from the disease.
fluid.
The spores at once attach. themselves to, and enter, other blood cells, and proceed to undergo a similar evolution from a tiny colourless speck to the pigmented parasite, whose pigment is derived from the destroyed blood cell, and later to the mature sporocyst, which in turn breaks up and sets free a fresh brood of spores in the blood..
The next notable advance was made by Golgi, of Pavia in North Italy. Studying. the mild spring fevers, he noticed that all the parasites in any particular case are at approximately the same stage of development. If one was found sporulating, then all would be in a state of maturity. He further observed that the attack of fever is always coincident with the rupture of a crop of the parasites, being evidently due to the setting free in the blood of some toxin or But, sir, this is premature. I have claimed poison when the parasite-containing cells break the death-sentence before I have made my case up. He found that there are marked differences against the mosquito. Let me tell you, stage between the parasites that cause the tertian by stage, the story of how we have arrived at and quartan forms of malarial fever, and that our present knowledge of the relation that the cause of the recurrence of the fever, and the exists between this insect and malaria, than fever every other day and every third day which there is none more interesting or prac-respectively in these two forms of intermittent tically important among all the fairy-like tales fever, is that the tertian parasite matures in of scientific research. It is a curious circum- 48 hours, while the life-cycle of the quartan stance that long before science heard of the parasite is 72 hours. subject it was a popular belief that mosquito- bites caused malaria, among the natives of regions so widely apart as the plains of Italy, the swamps of East Africa, the jungles of Burma, and the backwoods of America. But the more commonly accepted article of faith, expressed by the name
A little later, other Italian observers differen- tiated a third species of the parasite as the cause of the more malignant fevers of tropical climates. This was the form originally seen by Laveran in Africa, and is the most common in Hongkong, though the benign forms are also met with here. In this type the crops of
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