DIARRHEA (Gr. dia, through, and rheti, I flow), a disease or rather a tribe of dis eases, characterized by an increase in the discharges from the bowels, which are usually unduly liquid, sometimes overcharged with bile, and sometimes the contrary. Diarrhea has many varieties and many causes; but the whole tribe of diarrheal diseases present certain relations in common, which have been studied of late years to a considerable extent from the preventive or sanitary point of view. Thus, it is observed of all of these diseases, without exception, that they are more apt to prevail during summer and autumn than during the earlier seasons of the year; and it is also well established that their prevalence is to a great extent dependent on the intensity of the solar heat, so that a temperature above 60° F. seems to be almost essential, under ordinary circum stances, to their epidemic diffUsion. Moreover, it has been shown that the decompo sition of organic matters in the neighborhood of human dwellings, and the introduction of the products of decomposition into the food, drink, or air used by the healthy, has been a direct exciting cause of diarrhea in a great number of instances where the dis ease has been locally epidemic; from which it is inferred that the real source of diarrheal diseases is usually to be found in a morbid poison closely associated with the process of putrefaction, although not, perhaps, necessarily generated during that process. It has been noticed that cold and wet seasons are the least favorable to the production of diarrhea, which is explained on the theory above alluded to by the rapid removal in such seasons of all organic debris; and there is little doubt that this explanation is correct, as the converse is equally true, the combination of heat with long continued drought being almost sure to waken into life the epidemic seeds of diarrhea. Again, it is noticed that where drainage is imperfect, and drinking water impure, diarrhea' dis eases are specially apt to occur (see CnoLErta.); the class of the population most apt to be affected being those who occupy low levels, or who are otherwise exposed to the influence of this aqueous or gaseous poison. Infants are especially apt to suffer from diarrhea, and a large number of the infantile deaths in many English towns are caused either directly by this disease, or by the abuse of stimulants and narcotics for its cure.
Diarrhea is either simple, bilious, or choleraic; the last form has already been dis cussed. See CIIOLEItA. The ancients applied the name lientery to a diarrhea in which the dejections consisted of matters not digested, or very partially so; this form is, how ever, very unusual, at all events iu this country. Dysentery (q.v.) is also a form of diarrheal disease; as is the form of fever (q.v.) called gastric, typhoid, or enteric fever..
Simple and bilious diarrhea probably often differ only in degree; they are both distin guished from the advanced stages of cholera and dysentery by the presence of abun dance of biliary coloring matter in the stools, and by the absence of the distinctive feat ures of the other two diseases as described elsewhere. Diarrhea frequently depends on organic disease, either of the intestines themselves, or of the liver, kidney, or spleen. It is also one of the most common symptoms of the advanced stage of consumption (q.v.).
When diarrhea is plainly the consequence of improper food or drink, when it is very recent, when the strength of the patient is not much impaired, when there is much griping pain or distension of the belly, when the evacuations arc very unnatural in character, and especially when they are dark colored and very fetid; when the disease has been preceded by habitual constipation (q.v.), and when thero is no organic disease to be discovered, it is well to let diarrhea run its course, at all events for a time, and either to aid it by small doses of very simple laxatives, or, at all events, to abstain from hastily checking the discharge, which in these cases is to be regarded as a truly curative and beneficent process, calculated to disburden the system of some poisonous or dele terious substance, and only requiring time for the restoration of the patient to health. In other cases, especially of febrile diarrhea, an emetic of ipecacuanha at the very beginning will sometimes remove the disease with remarkable rapidity; and in most forms of diarrhea it may be alleged that this medicine (in doses of from one to five or even tan grains) is well borne. Sometimes it is combined with opium in the form of Dover's powder. Vegetable astringents, as catechu, kino, tannin, =rico, logwood, arc also much employed both in acute and chronic cases; some prefer the acetate of lead, with opium (which, however, is perhaps more suitable to dysentery). It should be observed that in some forms of diarrhea the use of opium, though a most powerful remedy, is contraindicted by the state of the constitution; it should In no case be largely given without medical advice. In many chronic cases the metallic tonics and astrin gents are of service—e.g., iron, sulphate of copper, zinc, and bismuth. In a very large class of cases, especially of infantile diarrhea, depending upon a too acid state of the secretions, the leading remedy is chalk, either in powder or in the very serviceable form of the mistura eretn {mixture of chalk) of the pharnmeorovias, from one to three-dessert spoonfuls of which may given after every disturbance of the bowels. Lime-water, mixed with milk in the proportion of one to four or five, is easily given to very young children, and serves nearly the same purpose.