Health on the Farm: A Manual of Rural Sanitation and Hygiene

by H. F. Harris

Malaria is a disease produced by a parasite belonging to the very lowest order of animal life—the Plasmodium malaria, which is conveyed from man to man by that genus of mosquitoes called the Anopheles. The parasite attacks and destroys the red cells of the blood, and produces a poison that causes the symptoms characteristic of malaria.

Course of the Disease.—The most common and well-recognized symptoms of malaria are those that occur in that variety of the disease which is known as malarial or intermittent fever. In this type the patient—who may or may not have at intervals for some days noticed chilly sensations, a feeling of fullness in the head, and general bodily depression—is suddenly seized with a chill followed by a high fever and subsequent profuse perspiration; after these symptoms subdue, which generally requires several hours, the patient returns to a practically normal condition and feels, on the whole, well until the next attack occurs. These chills-and-fever paroxysms occur at various intervals depending upon the character of the parasite inducing them, the most common form being that which produces a chill every day. In some instances the malady comes on more insidiously, there being no marked chills but only periodical elevations of temperature.

In the more chronic forms of the disease the unfortunate victim is frequently subjected for years to attacks of fever coming on at irregular intervals, the patient being more or less of an invalid throughout the course of the disease. In other instances the brain becomes affected, producing very alarming symptoms; and in quite a proportion of cases the malady ultimately terminates in chronic Bright's disease.

Treatment of the Disease.—Most fortunately, we have in quinine, when properly administered, a medicine that in practically all instances acts as a specific in this affection; but it should be used only on the advice and under the directions of a physician. In the more chronic forms of the disease, combinations of arsenic, with such tonics as nux vomica, iron, and small doses of some of the preparations of mercury, produce permanent cures where quinine has failed. It is of the utmost importance that attention be given to the treatment, as, so long as the patient remains with the parasites in his blood, so long is he a menace to his friends and neighbors.

Mode of Infection Through Mosquitoes.—The most brilliant triumph in modern medicine, and one of the most creditable achievements of human ingenuity, has been the absolute demonstration that malaria is carried from man to man by means of the Anopheles mosquito, and that the disease can, in nature, be produced in absolutely no other way. This is not a theory, but it is a fact which has been demonstrated in its every detail beyond dispute, and we are now happily in a condition to reject our venerable notions concerning bad air, miasma, etc.

Before describing the method by which infection takes place, it is well to say a few words concerning the mosquito that acts as a carrier of the disease, which may be easily differentiated from other similar gnats. The malarial mosquito has a body which is placed parallel to and almost on the same plane with the front portions of the insect, and as a consequence, when at rest on walls or other objects, the back of the body sticks out almost or quite at right angles with the surface upon which it is resting. The back portion of the common mosquito forms an angle with the front part of its body, with the effect that both ends of the insect point toward the object upon which it rests. There are still other differences that clearly differentiate the malarial from the common mosquito, but the one given ordinarily serves to distinguish between them. The malarial mosquito is pre-eminently a house-gnat, being scarcely ever seen in the woods or open, but may be found—oftentimes in great numbers—in all malarial localities, lying quietly during the day in dark corners of rooms or stables. This mosquito practically never bites in the day, but will do so in a darkened room, if a person will remain perfectly quiet; their favorite time for feeding is in the early parts of the night and about daybreak—all of which accounts for the fact, long observed, that malarial fever is almost invariably contracted at night. The malarial mosquito bites and then goes back to some dark corner where it remains quiescent for forty-eight hours, at the end of which time it again descends to feed. Contrary to the general opinion mosquitoes bite many times, and frequently remain alive for months—the malarial mosquito particularly living in cellars and attics oftentimes throughout the entire winter.

If one of these mosquitoes bite a person with malaria, the parasites are sucked in along with the blood and pass into the stomach of the gnat, making their way ultimately into the body substance; here the parasites undergo a series of multiplications, a single one of them sometimes producing as many as ten thousand young malarial parasites. After the parasites have developed fully, which requires eight days in warm weather, they make their way to the venom-gland of the mosquito and there remain until it bites, when they are injected into the body of the individual attacked along with the poison.

After getting into the human blood, each parasite attacks a red-blood cell, bores into it, and grows at the expense of the cell until it reaches maturity, at which time it divides up into from seven to twenty-five young parasites which are liberated and each in turn attacks a new cell. This process goes on until a sufficient number of parasites are produced in the individual to cause the symptoms of malaria, and the new subject of the disease thereafter becomes a source of danger to others in the vicinity through the intervention of still other malarial mosquitoes.

Malaria Avoidable.—From the foregoing it is seen that the proper way to avoid malaria is so to screen houses that mosquitoes cannot enter them. Persons in malarial districts should not sit on open porches at night, and should be careful to sleep under properly constructed nets. If this be done, there is absolutely no danger of anyone ever contracting the disease. It will be well observed that these precautions are not necessary in the daytime, as the malarial mosquito rarely attempts to bite during this period.

It should be remembered by those who have the disease that they are a constant source of danger to people living in the vicinity, and they should be doubly careful as long as the disease persists to avoid being bitten by mosquitoes at night. It is furthermore their duty to vigorously treat the disease until the parasites are no longer present in their bodies, at which time they cease to be a menace to others.