MALARIA, an Italian colloquial word (from mel's, bad, and aria, air), introduced into English medical literature by Macculloch (1827) as a substitute for the more restricted terms marsh miasm or paludal poison. By very general consent the word is understood to mean an actual poisonous substance existing as a separate entity, and giving rise to the definite unhealthy condition of body known by a variety of names, such as ague, intermittent (and remittent) fever, marsh fever, jungle fever, hill fever, "fever of the country," and "fever and ague." By a figure of speech, the name of malaria is often applied to the disease itself ; strictly speaking, the effects on the human body are "malarial fever," or manifestations of the "malarial process." The existence of a specific malaria-poison is a pure hypothesis ; and it has been attempted by a, respectable minority to dispense with the hypothesis of an actual poisonous agent, and to find the cause of intermitt-ents and remittents in the excessive and sudden abstraction of heat through damp and cold after sunset from the bodies of individuals who had previously endured great solar heat. In either view, the unknown cause of ague is denoted with sufficient etymological accuracy by the word malaria.
A single paroxysm of simple ague is much the same in all countries, temperate, subtropical, or tropical. It may come upon the patient in the midst of good health, or it may be preceded by some malaise. The ague-fit begins with chills proceeding as if from the lower part of the bock, and gradually extending until the coldness overtakes the whole body. Tremors of the muscles, more or less violent, accompany the cold sensations, beginning with the muscles of the lower jaw (chattering of the teeth), and extending to the extremities and trunk. The expression has meanwhile changed: the face is pale or livid ; there are dark rings under the eyes; the features are pinched and sharp, and the whole skin shrunken; the fingers are dead white, and the nails blue. All those symptoms are referable to spasmodic constriction of the small surface arteries, the pulse at the wrist being itself small, hard, and quick. In the interior organs there are indications of a compensating accumulation of blood, such as swelling of the spleen, engorgement (very rarely rupture) of the heart, with a feeling of oppression in the chest, and a copious flow of clear and watery urine from the congested kidneys. The body temperature will have risen suddenly from the normal to 103° or higher. This first or cold stage of the paroxysm varies much in length ; in temperate climates it lasts from one to two hours, while in tropical and subtropical countries it may be shortened. It is followed by the stage of dry heat, which will be prolonged in proportion as the previous stage is curtailed. The feeling of beat is at first an internal one, but it spreads outwards to the surface and to the extremities ; the skin becomes warm and red, but remains dry; the pulse becomes softer and more full, but still quick; and throbbings occur in exposed arteries, such as the temporal. The spleen continues to enlarge ; the urine is now scanty and high-coloured ; the body temperature still rises (up to 104° or 105° or even higher); there is considerable thirst ; and there is the usual intellectual unfitness, and it may be confusion, of the feverish state. This period of dry heat, having lasted three or four hours or longer, comes to an end in perspiration, at first a mere moistness of the skin, passing into sweating that may be profuse and even drenching. Sleep may overtake the patient in the midst of the sweating stage, and he awakes, not without some feeling of what he has passed through, but on the whole well, with the temperature fallen almost or altogether to the normal, or it may be even below the normal, the pulse moderate and full, the spleen again of its ordinary size ; the urine that is passed after the paroxysm deposits a thick brick-red sediment of urates. The three stages together will probably have lasted six to twelve hours. The paroxysm is followed by a definite interval in which there is not only no fever, but even a fair degree of bodily comfort and fitness ;, this is the intermission of the fever. Another paroxysm begins at or near the same hour next day (quotidian ague), or the interval may be forty-eight hours (tertian ague), or seventy-two hours (quartan ague). It is the general rule, with frequent exceptions, that the quotidian paroxysm comes on in the morning, the tertian about noon, and the quartan in the afternoon. Another rule is that the quartan has the longest cold stage, while its paroxysm is shortest as a whole ; the quotidian has the shortest cold stage and a long hot stage, while its paroxysm i3 longest as a whole. The point common to the various forms of ague is that the paroxysm ceases about midnight or early morning. Quotidian intermittent is on the whole more common than tertian in hot countries ; elsewhere the tertian is the usual type, and quartan is only occasional.
If the first paroxysm should not cease within the twenty-four hours, the fever is not reckoned. as an intermittent, but as a remittent.
Remittent is a not unusual form of the malarial process in tropical and subtropical countries, and in some localities or in some seasons it is more common than intermittent. It may be said to arise out of that type of intermittent in which the cold stage is shortened while the hot stage tends to be prolonged. A certain abatement or remission of the fever takes place, with or without sweating, but there is no true intermission or interval of absolute apyrexia. The periodicity shows itself in the form of an exacerbation of the still continuing fever, and that exacerbation may take place twenty-four hours after the first onset, or the interval may be only half that period, or it may be double. A fever that is to be remittent will usually declare itself from the outset: it begins with chills, but without the shivering and shaking fit of the intermittent; the hot stage soon follows, presenting the same characters as the prolonged hot stage of a quotidian, with the frequent addition of bilious symptoms, and it may be even of jaundice and of tenderness over the stomach and liver. Towards morning the fever abates ; the pulse falls in frequency, but does net come down to the normal ; headache and aching in the loins and limbs become less, but do not cease altogether ; the body temperature falls, but does not touch the level of apyrexia. The remission or abatement lasts generally throughout the morning ; and about noon there is an exacerbation, seldom ushered in by chills, which continues till the early morning following, when it remits or abates as before. A patient with remittent may get well in a week, under treatment, but the fever may go on for several weeks ; the return to health is often announced by the fever assuming the intermittent type, or in other words, by the remissions touching the level of absolute apyrexia. Remittent fevers (as well as intermittents) vary considerably in intensity; some cases are intense from the outset, or pernicious, with aggravation of all the symptoms - leading to stupor, delirium, collapse, intense jaundice, blood in the stools, blood and albumen in the urine, and, it may be, suppression of urine followed by convulsions. The severe forms of intermittent are most apt to occur in the very young, or in the aged, or in debilitated persons generally. Milder cases of malarial fever are apt to become dangerous from the complications of dysentery, bronchitis, or pneumonia. Severe remittents (pernicious or bilious remittents) approximate to the type of yellow fever, which is conventionally limited to epidemic outbreaks in western longitudes and on the west coast of Africa. Blood in the urine has been described by several recent writers as distinctive of a form of bilious remittent occurring at a number of malarious localities in the tropical zone of both hemispheres. The remittent type occurs wherever and whenever the malarial conditions are severe ; when it has appeared in colder climates, it has usually been at the height of an epidemic of intermittent. With all the foregoing statements, it should be borne in mind that, anomalies are frequent.
Of the mortality due to malarial disease a small part only is referable to the direct attack of intermittent, and chiefly to the fever in its pernicious form. Remittent fever is much more fatal in its direct attack ; it often kills in the first few days, according to its initial intensity or the severity of the complications. But probably the greater part of the enormous total of deaths set down to malaria is due to the malarial cachexia. The malarial cachexia may be either the sequel of one or more actual attacks of fever, or it may arise insidiously in those who inhabit a malarious district and have never experienced the sharp paroxysms of fever. In the latter case, malaria is almost as much an ethnological as a pathological factor. The dwellers in a malarious region like the Terai (at the foot of the Himalayas) are miserable, listless, and ugly, with large heads and particularly prominent ears, flat noses, tumid bellies, slender limbs, and sallow complexions ; the children are impregnated with malaria from their birth, and their growth is attended with aberrations from the normal which practically amount to the disease of rickets. The malarial cachexia, that follows definite attacks of ague consists in a state of ill-defined suffering, associated with a sallow skin, enlarged spleen and liver, and sometimes with dropsy.
Nearly allied to the malarial cachexia is the so-called state of masked ague. Many common ailments have been set down to malaria, without sufficient reason ; but there is hardly any doubt that intermittent paroxysms of neuralgia, especially of the supra-orbital nerve (brow-ague) and of the infra-orbital (tie douloureux), are often malarial in origin. These non-febrile effects are apt to follow exposure to malaria.; they occur (not exclusively) in those who have had fever and ague ; they are sometimes accompanied by suggestions of the cold, and hot, and sweating stages of the true paroxysm ; and they often yield to the great anti-malarial remedy, quinine. Such patients have the general ill-health and suffering, as well as the pallor, of the malarial cachexia.
The morbid anatomy of malarial fevers is chiefly confined to congestions and enlargements (with textural changes) of the spleen and liver. One of the most salient pathological facts is the occurrence of black pigment in the blood, and deposits of it in the spleen, liver, and other parts. The malarial process sometimes leads to ulcerations and sloughing of the mucous membrane of the great intestine, not distinguishable from those of dysentery. The malarial fever of Rome is often associated with more or less of swelling and, it may be, even ulceration of the lymphatic follicles of the small intestine, as in typhoid fever ; the same anatomical condition was associated with much of the malarial fever of the American Civil War (typho-malaria).
Geographical Distribution, and Prevalence. - Malaria has been estimated to produce one-half of the entire mortality of the human race ; and, inasmuch as it is the most frequent cause of sickness and death in those parts of the globe that are most densely populated, the estimate may be taken as at least rhetorically correct.
In the British Islands, sporadic cases of ague may occur anywhere ; but malaria is not now endemic except in a few localities, among which may be mentioned certain parishes on the Essex side of the Thames estuary. In France there are several districts that are still notoriously malarious. In the interior these are chiefly found in the valley of the Loire (Sologne) and of its tributary the Indre (Brenne), and also in the valley of the Rhone, more particularly near the confluence of the Saone (Dombes, Bresse). France has two great coast regions of malaria, - the one on the Atlantic seaboard, from the estuary of the Loire to the Pyrenees, with especial intensity in the Charente, and the other on the Mediterranean coast, from the Pyrenees to the Rhone delta. The most considerable malarious district of Switzerland is in the Rhone valley from Sion to the Lake of Geneva. In Germany, the upper valley of the Rhine and the sources of the Danube have a certain character for malaria ; but it is chiefly on the western seaboard of Schleswig-Holstein and in the moors and marshes of Oldenburg, Hanover, and Westphalia that the disease is endemic. Scarcely any province of Holland can be said to be quite free from it, while Groningen, Friesland, and Zealand (with brackish marshes) are the most unhealthy. The parts of Belgium that are almost or altogether exempt are the high-lying districts of Brabant, Namur, and Liege. In Sweden, malaria is endemic in the central depression of the country (especially on the shores of Lake Wener), and it has of late years spread northwards in epidemic outbreaks. For the countries of southern and eastern Europe (Spain and Portugal, Italy, Hungary and other Danubian states, Turkey, Greece, southern Russia), the language used to describe. the prevalence of malaria has to be pitched in a somewhat higher key. There are certain pestilential districts of those countries where almost the half of the population suffers from ague, and there are even limited areas which are too malarious to be inhabited. The lower basin of the Danube (from above Vienna to the Black Sea), and the basin of its tributary the Theiss, are in the first rank. Both sides of the Adriatic have malarious Roman Campagna, the Pontine Marshes, the neighbourhood of Capua, and the Neapolitan and Calabrian coasts. Sicily is highly malarious, both in the plains and in the higher districts ; and that is equally the character of Sardinia, Corsica, and the Balearic Isles. Greece, the Ionian Islands, and Crete take a high place among European malarious countries ; there are also numerous unhealthy localities on the shores of the Caspian and Black Seas and in Asia Minor. For countries in both hemispheres situated between 35° N. and 20° S., to describe the prevalence of malaria in detail would be practically to give the whole geography within those latitudes. The regions of special intensity are the west coast of Africa, the American seaboard (with the West Indies) from the Gulf of Mexico to Pernambuco, parts of India (the Terai, the Doab, the Sunderbunds), parts of Sumatra, of Java, and of Borneo. Gibraltar, Malta, Aden, Singapore, and Manila enjoy a comparative immunity from fever ; the healthiest islands of the West Indies are Barbados, St Vincent, and Antigua.
In England, the fen district of the eastern counties, Romney Marsh in Kent, and the marsh district of Somerset have in great part ceased to be malarious within recent memory; and there has been a proportionate improvement, through drainage, in most parts of Holland, in some of the malarious districts of France and Italy, and in Algiers. Portsmouth in England and Rochefort in France are examples of towns that have entirely lost their evil repute for malaria ; and there are many towns in the United States, as well as in the East, which are much less malarious than they used to be. Wherever malarial fevers have become less frequent, they have also become milder in type. On the other hand, malaria has become intense where it was formerly unimportant or altogether unknown. It is incredible that the Roman Campagna could have been so malarious at the time of the empire as it is now ; places on the coast, such as Ostia and Palo (Alsium), which are now almost uninhabitable in summer, were then the favourite summer resorts of the rich ; while the Campagna, which is now almost entirely given up to pasturage, was not only densely populated, but was even specially commended as salubrious. In North Africa, Asia Minor, and the East, malaria has taken possession of the ruined sites of ancient cities, and of large tracts of land that must have been at one time highly cultivated, but are now treeless, barren, and sometimes marshy. Of recent years malaria has appeared in Reunion and Mauritius, and it has reappeared in Connecticut ; in the two islands the associated circumstances are somewhat complicated, but they relate to changes in the cultivated area. The reappearance of ague in New England and the recent appearance of a form of masked ague in New York and elsewhere are at present unaccounted for. Earthquakes were said by older writers to have brought malaria to a locality ; a recent and well-authenticated instance is that of Amboyna in the Moluccas, which has become strikingly unhealthy since the earthquakes that occurred in it in 1835.
Among the numerous military enterprises into whose records malaria enters largely, may be mentioned the expedition against Carthagena (1741), the Walcheren expedition (1810), and the capture of Rangoon (1824). Recent enterprises in which malarial fever has been a great factor are the expedition against Achin by the Dutch (1873), the occupation of Cyprus by the English (1878), and the subjugation of Tunis by the French (1881). Schemes of colonization, such as the Darien scheme (1701), have sometimes been frustrated by malaria. Of historical personages, James I. and Cromwell died in London of malarial fever, the latter of a pernicious tertian.
There have been numerous historical epidemics of intermittent and remittent fever, from that of 1557-5S (which spread over all Europe) clown to that of 1872, which prevailed simultaneously in Europe, North America-, and southern India. The epidemic or pandemic prevalence of intermittent and remittent fever in certain years probably finds its explanation in the meteorology of those years, but no uniform law has been discovered. Whenever malaria has settled endemically in a new locality, there had been epidemics coming and going for some time previously.
Localities. - The most malarious localities are the deltas and estuaries of rivers (Ganges, Euphrates, Po, Mississippi, Orinoco), low-lying country that is apt to be inundated (Danubian states), tropical or subtropical -forests in which there is a moist atmosphere, with stagnation of the air and rank vegetation (jungles), tracts of land that have been cleared of trees and have gone out of cultivation, being in more cases dry than wet (Roman Campagna, Tuscan Maremma, many parts of Persia, Asia Minor, and North Africa, including the sites of ruined cities), inland swamps and marshes (Pontine Marshes), and situations on the coast where the tidal and fresh water join to form brackish marshes (mangrove swamps of the West Indian, Central American, Brazilian, and West African coasts). The mangrove is associated with the roost pestilential localities ; it springs "like a miniature forest out of the greasy mud-banks, the bright green colour of the bushes reminding one of the rank grass in a churchyard" (C. Darwin). In all thuse localities there is a soil, usually wet but sometimes dry, rich in the products of vegetable decay ; the soil has been either deposited by rivers and tides, or it has formed on the spot out of the undisturbed accumulation of decaying vegetation season after season over a long period. There is, however, a second great class of malarious localities, distinguished by characters that are to some extent the opposite of the foregoing. These are barren rocks (Ionian Islands, Hong Kong, parts of Baluchistan, De Los Islands near Sierra Leone); high table-lands more or less barren (Deccan, Mysore, Persia, New Castile); mountainous regions (Andes, Rocky Mountains) ; prairies of North America and savannas of Venezuela and Brazil; sandy plains (North Africa, Rajputana, Sindh). A somewhat exceptional locality for malaria is on board ship at sea ; there are several well-authenticated instances of epidemic outbreaks at sea, in most cases referred to the putrid bilge-water, and in one case to a cargo of wet deals from the Baltic.
There are several localities whose exemption from malaria has been thought remarkable. Among these, Singapore has long been noted ; other instances are the Amazon (as compared with its tributaries and with the Orinoco), the pampas of the La Plata and the Parana, marshy parts of Australia, New Zealand, and New Caledonia, and the marshy Bermudas. The explanation given of the exemption of Singapore, where many of the supposed malarial conditions are preseut, is that the range of temperature (diurnal and annual) is small ; the explanation for the Amazon is that a wind constantly blows up the river from the sea (not reaching the side streams), which serves to equalize the day and night temperature and to obviate the nocturnal radiation of heat.
Jicilarious Seasons. - In temperate climates autumn is the season when malaria prevails most. " In the autumn, and after the harvest has been gathered, when the ground is covered with its debris, when the rain falls in torrents and when the solar heat has acquired its greatest intensity, all the conditions of greatest quantity of vegetable matter, of moisture, and of highest temperature are united, so that the season which realizes the hopes of the husbandman is the period of pestilence and of his greatest danger " (R. Williams). In the equatorial regions of the East Indies, Africa, and America, the rainy season (May to July or August) is most unhealthy, and especially the time of commencement of the rains and the time of cessation ; on the west coast of Africa the months of February, March, and April, which are the hottest months of the year, are at the same time the most healthy. But while autumn and the time of the rains are the malarious season for those localities that are distinguished by wet soil, rank vegetation, &c., it is summer, or the time of extreme heat and drought, that is the unhealthy season fur the localities distinguished by dryness of the soil and often by barrenness. The hill fever of the Deccan and Mysore is often most prevalent and most severe in the hottest and driest seasons iu Algeria there is most fever when the country is parched to a desert. The malarial'season in the Tuscan Maremma is from June to the middle of September. In military experience it has frequently happened that malaria has attacked the troops in the hottest weather after camping in the dried-up water-courses of uplands, or in parched meadows and sandy levels that are apt to be flooded only in winter.
Conditions of Origin. - In all localities and at all seasons, it is at or after sunset that the malarial influence prevails, and it tells most when a cold night follows a hot day. Perhaps the most constant fact relating to malaria is that it goes with watery exhalations and with the fall of dew. On wet soils, and over marshes, swamps, and jungles, the aqueous vapour condenses as the air cools ; while on dry surfaces the rapid radiation of heat causes a heavy dew-fall. The occurrence of malaria on bare rocks, parched uplands, and treeless tracts of dry fallow land may have several associated circumstances ' but that which has been most uniformly observed in such localities is great diurnal range of temperature, with rapid radiation of heat after sunset, and copious fall of dew. The " hill fever " of Mysore occurs among bare rocks and stones and brown earth ; at the hottest season (March to June) the diurnal range of the-shade temperature may be 20° to 30°, while the rocks in the sun may show a surface temperature up to 220°, and undergo a rapid coolino. after sunset. The most malarious locality at all times cooling year on the Orinoco is around the great cataract, where the banks of the river for some distance are covered with bare black rocks piled to a considerable height ; the rocky substance and the black surface combine to produce the greatest absorption of heat and the most rapid radiation, and the rocks there, as well as in other parts of South America and in India, are credited by the natives with giving off poisonous exhalations which cause the fever. Among the conditions of origin the predisposition of the human subject takes a prominent place. Those who have been habituated to extreme heat, and are on occasion exposed to cold and damp, are likely to acquire intermittent or remittent fever ; and those who are poorly clad, housed, and fed are most likely. Fires at night in a malarious locality are a well-known protection from fever; the cover of trees (preventing the radiation of heat) is also a protection. Those who have had ague before are liable to have it again on exposure in a malarious locality, or to chill anywhere.
Diffusion of Malaria. - On the hypothesis that malaria is a poisonous substance, it is permissible to speak of its diffusion. It acts for the most part only within a few feet of the ground ; in the East Indies the raising of dwellings on piles serves to keep off, or at least lessen, the liability to fever, and the Indians in South America escape it by sleeping in the branches of trees. Although it is not known to act beyond a few feet from the earth's surface, it may produce fever in localities situated at a height of 7000 to 9000 feet above the sea-level. It sometimes acts at a distance from its supposed place of origin. Thus, it it is said to have caused fever on board ships lying 2 or 3 miles off a malarious shore, although it is more usual for ships at even a short distance from the shore to escape. In West Indian experience it has been known to render the high limestone ridge more unhealthy than the swamp at its foot, and a similar experience has occurred on the Kentish shore of the Thames estuary, and at other parts of the English (Channel) coast. There are instances where it has, so to speak, travelled along a narrow valley from an unhealthy marsh to a salubrious situation. Although a still night is most favourable to its production, there is a popular opinion that it is carried by the wind. In many malarious localities there is a definite "ague line," beyond which the noxious influence is not felt. A belt of trees, or even a wall, will " keep it off." It clings to those surfaces that are most easily bedewed, Situations to windward of a malarious swamp are usually reckoned safe.
Hypothesis of Malaria. - Malaria is known only by its effects on the animal body ; the effects, although they vary much in intensity, are uniform, definite, or specific, and are characterized by a truly remarkable periodicity. The oldest and most prevalent hypothesis of malaria is that it is a specific poison generated in the soil. Perhaps not every soil is capable under circumstances of causing malaria, but it is difficult to assign limits to its potential presence. There are seemingly well-authenticated cases of malarial disease appearing during the making of railway cuttings, canals, and other excavations in places where malaria had not previously been known; and there is sufficient evidence that malaria has appeared in the track of cultivation in the western States of America, and that it follows on the upturning of virgin soil, and even of soil that has been long fallow. Attempts have been made, without success, to separate a malarious poison from the gases generated by swamps, or from the air of malarious localities. Still more frequent and elaborate attempts have been made to discover the hypothetical poison among the numerous minute vegetable organisms that occur in the soil of malarious (and non-malarious) places; and these also have hitherto yielded no solid result. Another hypothesis is that malaria is a "telluric intoxication," generated by the vegetative power of the soil when that power is not duly exhausted by plant growth. Lastly, there is an hypothesis that malarial fevers are caused by the excessive and sudden abstraction of heat from the body under the influence of cold and damp, and that the specific effects of the nocturnal chill, amounting to intermittent and remittent fever, are most usual and most marked iu hot climates because of the antecedent exposure of the body to great solar heat.
Remedies. - Cinchona or Peruvian bark (with its alkaloid quinine) is a remedy universally applied with good effect in the treatment of malarial fevers. The treatment is usually commenced during the first intermission or remission. There is no good evidence that the taking of quinine wards off the attack of malaria. The extent of cinchona planting in southern India, Ceylon, Jamaica, and elsewhere is the best measure of the value of quinine as a remedy, and more particularly as a remedy for ague. Arsenic has proved one of the most efficient substitutes for quinine. The dwellers in malarious localities have found in opium a palliative of the misery induced by the malarial cachexia.
Literature. --Hirsch, Geographisch-historischc Pathologic, 2d ed., Stuttgart, 1881, pt. i. sec. 7 (the bibliographical references appended to Ifirseh's chapter on malaria include upwards of eight hundred names) ; W. Ferguson, " On the Nature and History of the Marsh Poison," Trans. Roy. Soc. Edin,,ix.,1823 (omitted by Hirsch ; was the first to dwell upon the fact that malaria is often associated with heat and drought, and elevated rocky localities) ; Macculloch, Malaria, an Essay, &e., London, 1827; Robert MOAN P0151317.9, London, 1836-41, vol. ii., chapter on "Paludal Diseases"; Colin, Traitd des Pyres intermillcnics, Paris, '1870 (expounds the theory of "intoxication tellurigne "); C. F. Oldham, What is Malaria l and Why is it most Intense in list Clinzates I London, 1871 (a comprehensive review and acute criticism of established facts and current theories, with the motive of showing that there is no specific malarial poison) ; Morehead, Clinical Researches on Disease in India, London, 1856, vol. i. (for symptoms, diagnosis, and treatment of intermittent and remittent fevers) ; Fayrer, Climate and revers of India, London, 1882 (both general and clinical). (C. C.)