Pearls & Parasites

by Sir A. E. Shipley

Malarial fever, when it does not kill, leaves great weakness behind; and all who have watched malaria patients, or patients who are already recovering from an attack, cannot fail to have noticed the listlessness and want of interest in their surroundings and the lack of inclination to work that they all show. Apart from the mortality, the disease probably levies a heavier tribute on the capacity of the officers and officials who administer the British Empire than does any other single agency.

Before describing the organism which causes all this misery a word or two must be said about the distribution of the disease. Roughly speaking, malaria is confined to a broad irregular belt running round the world between the 4th isothermal line north of the Equator and the 16th line south. It is, however, said to occur occasionally outside these limits—for instance, in Southern Greenland and at Irkutsk in Siberia; but until recently the accurate diagnosis of the disease has been difficult, and too much reliance must not be placed on these statements. The chief endemic foci of the disease are along the banks and deltas of large rivers, on low coasts, and around inland lakes and marshes. Malaria is common all round the Mediterranean region: it was well known to, and its symptoms were clearly noted by, the early physicians since the time of Hippocrates. They even recognized the difference between the mild spring and summer attacks and the more pernicious effects of the autumnal fever. In France there are several prominent malarial districts: the valley of the Loire and its tributary the Indre, and the valley of the Rhone; also the sea-coast stretching from the mouth of the Loire to the Pyrenees, and again the Mediterranean sea-board. It occurs in Switzerland, and is found in Germany along the Baltic coasts, and on the banks of the Rhine, the Elbe, and other rivers, and in many other parts. Scarcely a province in Holland is quite free from it, and it is found in Belgium and around Lake Wener, in Sweden. It extends along the Lower Danube and around the Black Sea, and spreads across Russia, being especially prevalent along the course of the Volga and around the Caspian. From Europe it spreads over Asia Minor, and affects all Southern Asia as far as the East Indies, but in Japan it is curiously rare. It is also infrequent in Australia—where it is confined to the northern half of the continent—and in many of the Pacific Islands; and it is unknown in the Sandwich Islands, New Zealand, Tasmania, and Samoa. In America it is more common, and of a more severe type an the Atlantic sea-board than on the Pacific; in the last hundred years its northern limit is said to have retreated in the centre of the continent, though some observers think it is creeping further north in the Eastern States. In a mild form it is known around the Great Lakes, and in Canada and in New England; but it reaches a high degree of intensity in the Southern States, Mexico, Cuba, and Central America, where it probably played a greater part in ruining the projected Panama Canal than all the corrupt financing of the speculators in Paris. It extends throughout the warmer parts of South America, and is known in a virulent form all over Africa except the extreme south.

In Great Britain it used to flourish. The following extract from Graham’s ‘Social Life of Scotland in the Eighteenth Century’ shows what a part it played in the life of the Scottish peasant:

‘The one ailment to which they were most liable, and in which dirt had no share, was ague. This was due to the undrained land, which retained wet like a sponge, and was full of swamps and bogs and morasses in which “green grew the rushes.” Terribly prevalent and harassing this malady proved to the rural classes, for every year a vast proportion of the people were prostrated by it, so that it was often extremely difficult to get the necessary work of the fields performed in many districts. In localities like the Carse of Gowrie, which in those days abounded in morasses and deep pools, amongst whose rushes the lapwings had their haunt, the whole population was every year stricken more or less with the trouble, until the days came when drainage dried the soil, and ague and lapwings disappeared.’

In England it was once very prevalent. James I. died of ‘a tertian ague’ at Theobalds, near London, and Cromwell succumbed at Whitehall to a ‘bastard tertian ague’ in 1658, a year in which malaria was very widely spread and very malignant; and it is only within recent memory that the fen districts in Cambridgeshire and Lincolnshire, Romney Marsh in Kent, and the marshy districts of Somerset, have lost their evil reputation for ague. The older chemists in the towns in the fen districts still recall the lucrative trade their fathers carried on in opium and preparations of quinine with the fenmen during the first half of last century; but with the improved drainage of the fens this has all disappeared, and at present cases of endemic malaria appear to be unknown in England, though sporadic cases turn up at rare intervals. It was also very prevalent along the estuary of the Thames, both on the Essex and Kentish marshes. Pip in ‘Great Expectations’ says to his convict:

‘ “I think you have got the ague.” “I’m much of your opinion, boy,” said he. “It’s bad about here,” I told him. “You’ve been lying out on the meshes, and they’re dreadful aguish.” ’

Ireland, which appears at first sight peculiarly adapted for the disease, seems to have been remarkably free from it. It may be that the strong antiseptic quality of the peaty bog-water hinders the development of the larval mosquito.

Turning now to the cause of the disease, it is interesting to note that the discovery of the organism which produces all this misery and death took place just about the time when Koch was making his far-reaching investigations into the cause of tuberculosis. In 1880 Koch was at work on the tubercle bacillus; and in the same year a French army surgeon, named Laveran, looking down a microscope in a remote military station in Algiers at a preparation of blood taken from a malarious soldier, recognized for the first time the small organism which has played a larger part in human affairs than the greatest politician or general that ever lived. This small organism is an animal, not a plant. It belongs to the great group of single-celled organisms, mostly microscopic in size, called Protozoa, and it lives as a parasite inside the body of other animals, from which it abstracts what nutriment it needs. Before describing its structure and life-history, a word or two must be said about its surroundings in the body of man.

That blood consists of a fluid in which enormous numbers of cells called blood-corpuscles float is now a matter of common knowledge. These corpuscles are of two main kinds, the red and the white, but the red surpass the white in number, in proportions ranging from 300 up to 700 to 1. A cubic millimetre of blood contains about 5,000,000 red corpuscles; and since these act as the carriers of oxygen from the lungs to the tissues all over the body, and on their return journey carry away the carbon dioxide from the tissues to the lungs, where it is given off, it is obvious that the presence of a parasite in the red corpuscle will have a most serious effect upon the welfare of the body.