1941-02-01 — Page 7

Second Section

Hongkong Telegraph.

SATURDAY, FEBRUARY, 1, 1941.

COMBATING

MALARIA IN HONGKONG

Magazine Features

A corner of the Hongkong Govern- ment Malaris Bureau Inboratory.. A staff worker is oxamining morgúlto larvae kept for

hatching out.

As the name suggests, this disease was suppored to be caused by persons inhaling bad or night air't particularly the air from swamps or nurshes. Accordingly, not so long ago, almost everyone tightly closed their windows at night, to prevent the night air from entering their bedrooms, There is, of course, a very deflatte binection between swamps and malaria, but the night alr is quite blueless, and has no connection with the trans mission of the disease whatsoever.

Although the disease, matarla, has been recognised for many hundreds of years, the cause was not proven until comparatively recently. It is of considerable local interest that most important contribution towards the discovery of the mine of. the disease was made in this Colony and by a Hongkong doctor. At the beginning of this century Dr, later Sir Patrick Mamion, a mestical practitioner in this Colony and founder of the old Hong- Kong Medical School (now the Unzersity of Hongkong) had suspicions that a mosquito carrled malaria fram man to man.

Sir Patriel: conveyed his thewry to a friend of his, then an army medical corpa major (later Sir Honald Ross) and Hors spent several years in inten- sive research on the lines suggested by Mapson. These experiments were curried out mostly in India.

In order to understand how malaria is trattmitted, it must be appre- clated that all blood, whether human or animal, is really a fluid in which is suspended millions of tiny reit wells. The function of these little red cells is to carry oxygen to, and carbon dioxide gases from, the fissiles of the body. Normally there are some five millon of these in every cubic centimetre of blood.

Ross, in his invesilgationg divided his attention particularly to two fuctors, the study of the body of certain mosquitoes, und inuman blood. He found that the red blood cells, in the blood of persons suffering from malaria, contained .curious little budies which shewed up under the micro- scope when suitably stained or dyed. These bodies sometimes were found to be irregular in shape, but more often they resembled little signet

rings. the thick part of the ring stained red and the rest purple. These he proved later to be the parasites of malaria.

At the same time, he paid attention to the body of the anophelene mosquito, and he found that some of the females which had eggs in their bodies also had curious sickle-shaped bodles in their sulivary glands, and others had protrusions or lumps on the inside lining of their stomachs. Further, he found that the stoniąch was first infected, and that afterwards, the salivary glands became involved, the whole process taking about eight days.

Hoss demonstrated that on biting man, the female anophlene mosquito betually injected malaria parasites Into the human blood-stream, and that after an incubation period of about ten days the victim developed an Inter- millent fever when it was possible to demonstrate the mature malaria parasites in the red blood cells. Furthermore, after a short lapse of time, cach malaria parasite split up into several distinct parasites, which come ~plotely filled the red cell, eventually-upturing-it-On-each-supture-or explosion, as it were, the infected person experienced a sharp rise in tem- perature, with shivering and all the other symptoms of malaria.

The mystery about the transmission of malaria was finally settled for good and all, after the following experiments and dernonstrations were carried out by Ross.

A party of scientists left England and lived in a very malarlous part of southern Europe. The inhabitants in these parts were riddled with malaria. These scientists lived amongst the infected population, engaged in the same occupations, ale the same food, and drank the same water for two years or more, and never contracted malaria, because at nightfall they.. all retired within a mosquito-netted house and slept under nets at night, thus preventing mosquitoes from biting them.

A further series of experiments was carried out and, brielly, these con- sisted in transporting Infected mosquitoes from malarious countries and allowing them to bite 'volunteers' in England, people who had never been- In a malarious country in their lives. All the persons so bitten after the usual incubation period developed malaria, and it was possible to demon- strale molarla parasites in their blood.

An incubation

bottle is shown

in the right mid-

dla pieturo: Sevo-

ral grown mosqui- toes may be seen. On the left, an attendant domonstrates the Paris

Green pump "apparatus, by means of which larvae are poisoned.

*

Anti-malarial measures are directed against the propagation of the mosquitoes. In the insect's Hfe cycle, from egg to adult, there is a stage the farva-where the insect swims about freely in water but redres nir for its growth. The larvne lie horizontal to the surface of the water.

In brief, anti-malarial measures are as follows:

1.

Drainage of swampy land and removal of collections of water.

2. Arranging hill streams either permanently (cement concrete channels)

3.

5.

0.

7.

or thing." piling the stones up on either side of the stream

and

and straightening out the strears bed, so as to eliminate

as for s possible collections of water which would breed mosquitoes.

Oiling where certain streams or collections of water cannot be dealt with by drainage or training owing to the excessive cost. These are regularly sprayed with oil, usually at least once a week. The oil chokes the breathing apparatus of the laryne and they die.

All larvae which are found breeding are collected and hatched out in

a laboratory and identified and note taken of the number of harmless or dangerous types and where found!.

Paris green, an arsenical powder, is used instead of oil in certain selected cases. This netually polsons the larvae, but cannot be used where fish are present, or these are poisoned too.

The screening of houses with mosquito gauze wire netting and the use. of nels at night by people living in tnalarious areas.

The co-operatlan of householders in making frequent Inspections of their premises to see that their servants have not allowed water to collect in vessels-broken or unbroken-thus affording breeding places for mosquitoes.

8. Legislation prohibiting collections of stagnant water by anyghe, and

prosecution of the offenders.

Work of this nature is conducted in Hongkong by the Government Malarla Bureau, pictures of which are to be seen on his pare. The Bureau consists of a Matariologist-n doctor specially trained in this science- a technical assistant, nine Chinese Inspectors, all of whom are in uniform, and who are in charge of fairly large areas in the urban parts of the Island of Hongkong and the Mainland. Each Malaria Inspector is in charge of at least one foreman, and several gangs of coolics, whose job is to control the hill streams, drain swampy land and to oil regularly collections of water

be dealt with otherwise.

well-trained staff conducts

which

well-equipped inboratory with

the

Investigations, such as typing of the various mosquitoes and larvae sent in, examination of blood alides for malaria parasites, and research,"

All trains and aircraft are met on arrival, and searches are made in every instance for mosquitoes. All mosquitoes so found are sent to the Laboratory for identification and dissection to determine whether they are Infected with malaria paraslice or not.

(Photos: Ming Yuan).

On the left, an olling sprayer is being used:in different terrain. Below,

a trained stream which gives proper drainage and provents water collecting in 'stagnant pools,