INFANTS, DIARRHEAL DISEASES OF.—Gr., from through, and (Fir. to flow.
Definition.—Diarrhoea in itself can be regarded as a symptom only: a symptom indicative of increased motor activity and of increased, and perhaps perverted, secretory activity in the intestinal canal.
Disturbance of the intestinal activity is sometimes due merely to the pres ence in the alimentary tract of irritat ing and noxious material and the in creased secretion and peristalsis is to be regarded as an effort of nature to get rid of offending material; an effort which, if effective, and not unduly severe or pro longed, must be considered as entirely salutary in its character. More fre quently, diarrhoea, especially in infants, must be regarded as one symptom only of an intoxication of the system by toxins the product of pathogenic micro-organ isms present in the alimentary canal: a symptom important in itself, but not to be considered apart from other symp toms of systemic intoxication,—such as fever, quickened and enfeebled cardiac action, and nervous prostration.
In many of these cases inflammatory changes more or less extensive in char acter are set up in the walls of the intes tines; such changes may be due to some extent to the abnormal and irritating character of the intestinal contents, but, to a much greater degree, they result from the specific action of the bacterial toxins. In some instances the bacteria themselves appear to penetrate the tis sues of the intestinal wall; destructive changes are thus induced which not only aggravate the general symptoms, but, should the case survive, indefinitely re tard recovery.
Owing to the abnormal activity of peristalsis by which food is unduly hur ried through the alimentary tract and to an alteration in the various digestive fluids, either quantitative or qualitative, the process of digestion is performed more or less imperfectly; owing, also, to inflammatory changes in the walls of the intestine, absorption is hindered and general nutrition becomes rapidly paired. In some cases, where the diar rhoea is of a grave character, or persists throughout a long period of time, the emaciation becomes extreme.
Diarrhoea is thus of much importance as a clinical symptom; for this reason it has long been customary to group to gether under the name used generically all those disorders which have, as their prominent and most important symptom, an increased motor and secretory activity of the intestinal tract from whatever cause arising. This use of the name lacks
scientific precision; nevertheless, while our knowledge of many of the conditions met with in these disorders is still inexact and uncertain, it does not seem wise to attempt more precise definition.
Infants under the age of thirty months are peculiarly prone to diarrhceal dis orders. In such infants disorders of the intestinal tract present an etiology and pathology peculiar to themselves, and in them, to a much greater extent than in older children or in adults, has the dis ease a tendency to run a severe course, and in a large proportion of cases to ter minate fatally. For this reason the sub ject of infantile diarrhoea claims separate consideration.
Etiology.—If we inquire into the causes which induce this liability to diar rhceal disease on the part of infants, a few facts stand out prominently.
THE SEASON.—The diarrhceas of in fancy take a comparatively unimportant rank among infantile diseases during the cooler months of the year, but with the onset of warm weather they suddenly ac quire importance, owing to their general severity, to their large mortality, and to the frequency with which they are en countered. This is evidenced by the statistics of all large cities in the tem perate zones. Whenever the minimum temperature of the atmosphere for the twenty-four hours reaches the neighbor hood of 60° F., infantile diarrlueas as sume the character of a wide-spread epi demic. An attempt has been recently made by some English physicians to con nect the epidemic character of the disease with the temperature of the soil. Dr. Ballard, after careful investigation, states that the mortality from this class of dis orders does not begin until the ther mometer registers a temperature of 56° F. four feet below the surface. That there is any relation of cause and effect between the two facts, however, has in no way been proved.