Malarial Fevers

BY SAMUEL M. BEMISS, M.D.

In the medical nomenclature of this country the term malaria is synonymous with swamp or ague poison.

Malarial affections, therefore, comprise all those diseases or morbid manifestations which the swamp poison produces in the human organism.

This article is not designed to notice in a systematic manner any of these disorders which are not properly classifiable under the head of malarial fevers. It will, however, be necessary to make such references to the pathology of chronic malarial toxæmia as may serve to explain the influence this condition exerts in occasioning departures from type in the febrile attacks.

When a poison generated outside the human system obtains admission to it, and produces deleterious effects, three questions naturally arise: What is the essential character and natural history of this noxious agent? How does it obtain access to the human system? What is its mode of action when received?

In reference to the first of these questions, it must be admitted that the substantive essentiality of the malarial poison remains as yet undemonstrated. It is true, however, that the attempts at an objective study of this poison by means of the microscope and the cultivating retort point to the conclusion that it is an organism.

Its subjective or analogical study affords quite incontestable evidence in support of this conclusion. The leading features in the natural history of malaria are closely coincident with those of certain known organisms. It requires for its production suitable conditions of moisture, temperature, and a properly circumstanced breeding-place. Within certain bounds these conditions are requisite to the life and perpetuity of all organisms.

Again, when all the above-enumerated conditions correspond apparently in the most favorable degree, their continuous concurrence for a lapse of time is necessary before the poison manifests its presence. It is not improbable that this period of development may differ in different climates, but in this country we assume it to be about thirty days. If these facts related to some noxious organism visible to the eye, no doubt would be entertained that the presence of its germs in the places where it appeared was the indispensable condition. It would then follow that the concurrence of suitable meteorologic and telluric conditions with sufficient time for its growth and maturity were merely accessories to its perfect development. According to this theory, the coincidence of five circumstances is necessary before malaria can be fully matured—viz.: Its own specific germ; suitable soil or pabulum; suitable moisture; suitable temperature; sufficient time for its growth and development.

Certain physical qualities which pertain to the malarial poison can also be profitably made points of subjective study. These are very closely connected with the answer to the second question, or "How the malarial poison obtains access to the human system." They will therefore be briefly noticed in relation to the instrumentality of each in conveying malaria into the system.

The first to be mentioned is ponderability, which the following facts prove that malaria possesses:

Those different atmospheric states which affect the range of diffusion of known air-borne yet ponderable substances exert similar influences upon the malarial poison.

Altitude illustrates the ponderability of malaria by powerfully retarding its diffusion.

High readings of the barometer favor its aërial dissemination.

Fogs, smoke, dust, or floating particles presumably more buoyant than this poison may exert greater or less influence in overcoming the obstacle which ponderability attaches to malaria as an air-borne agent.

Currents of air passing continuously and steadily in one direction over the breeding-places of malaria increase the limits and intensity of toxic range.

The atmosphere is undoubtedly the medium by means of which malarial poison is most frequently brought into the human system. Liability to intoxication is increased in direct ratio to the proximity of points of exposure to places of development; to similarity of level; to situation in the line of prevailing winds which have traversed the breeding-ground; and, lastly, to the extent and fertility of the locality of production.

Whether malaria passes through the respiratory apparatus directly into the circulation, or is lodged upon the fauces and absorbed through some other surface, is not clearly ascertainable. It is certainly not deprived of its noxious qualities by stomach digestion, and therefore, sometimes at least, may reach the blood through the alimentary canal.

Malaria is miscible with water. It is capable of being carried by currents of water through distances and periods of time altogether undetermined, without losing either its toxic effects or, perhaps, the faculty of reproduction. It is more than likely that this means of conveyance has effected its distribution to continents and islands too widely separated to justify a belief that it was wind-wafted. No observations need be adduced to establish the water-borne habit of the malarial poison, or the positive liability to its toxic effects when received into the stomach through this medium. These facts have been well understood from the time of Hippocrates.

The matter of communicability of malaria by means of drinking water should not be dismissed without some allusion to the great probability that other fluids or solids are open to a similar charge. There is a widespread popular prejudice, especially notable in the southern part of the United States, that drinking milk occasions attacks of the endemic fevers. It is the usual custom to pour the evening supply of milk into broad uncovered pans, and allow it to remain exposed in the open air for consumption at the morning meal. This viscid fluid, so tenacious of ordinary air-borne particles, may well be suspected of entangling sufficient quantities of swamp poison to produce sickness if exposed where it is rife during a whole night.

A similar popular prejudice exists in regard to the muscadine grape, which flourishes best in swampy localities. The rough skin of this fruit, frequently covered with its own juice, offers favorable conditions for the adhesion of air-borne particles.

The malarial poison is not reproduced within the human system. This proposition is undeniable, since no intensification of the poison is produced by any degree of crowding of the sick which can be practised; neither do any conditions of contact with the sick ever impart malarial affections.

Malarial poison is specific. This allegation is sufficiently established by its specific effects on the human economy. There is no other agent known which is capable of originating morbid phenomena characterized by such marked diurnal periodicity.

It is not interchangeable with other specific poisons. This statement may be rested upon all fairly collected clinical observations.

There are no facts which justify the belief that malaria is capable of becoming mixed in the atmosphere, or outside the system, with any other specific morbific germ, so as to produce a third something which may give rise to compound forms of disease.

The answer to the second question which is best supported is, that the malarial poison is brought into the system principally by breathing an atmosphere impregnated with this miasm.

It is also ingested by being held in suspension in fluids used as drink or food; perhaps also by eating certain fruits or vegetables in their natural state whose external surfaces afford favorable conditions for its lodgment.

MORBID EFFECTS AND PHENOMENA WHICH FOLLOW ITS INTRODUCTION INTO THE HUMAN SYSTEM.—The discussion of the morbid process established by the malarial poison involves some difficult problems. A period of incubation must be admitted to follow the inception of the ague germs. But this period has no definitely marked limits. Perhaps it is a shifting one, according to the quantity or quality of the poison received, or the sudden or gradual manner in which it is received, or the state of receptivity of the system.

Certain facts seem to indicate very clearly that malarial poison is very slowly removed from a system which has been brought under its influence. These evidences of long systemic residence of the poison are principally displayed in those attacks which occur after long periods of removal from any surrounding where intoxication was possible. Vernal attacks may be classed in the same connection. In many instances the subjects of these long-delayed attacks have never suffered a paroxysmal seizure, and yet when some accidental derangement of health occurs, as from a fit of indigestion or a sudden wetting, they fall sick with one or another form of malarial fever.

It does not appear to me that we are justified in assuming that such attacks as I refer to are to be ascribed to secondary changes produced in either the fluids or solids of the system by the malarial poison. In so far as the clinical phenomena are worth anything in demonstrating the presence and agency of the specific malarial poison in these deferred attacks, they are precisely similar to those observed in paroxysms arising after a few hours' or a few days' exposure to marsh miasm.

But we find further proofs of the long-continued and silent manner in which malaria exerts its pathological influences in those enlargements of the spleen which occur without specific attacks of sickness. The alterations of nutrition in this organ are so characteristic of malaria that they can scarcely be supposed to depend upon those chances which determine the nature of secondary blood-impurities.