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.