CHAPTER VIII

THE DIARRHEAL GROUP OF DISEASES @

The diseases which may be grouped together as inflammations of the intestinal tract, and which possess in common the symptom diarrhea, were of much less importance during the World War than during any previous major conflict of which we have record. It will be the main attempt of this chapter, therefore, to show not only the fact of the greatly decreased incidence of these diseases as compared to that of earlier wars, but to study the causes of this decrease and to deduce, if possible, from this study the lines along which further progress in their prevention may be made.

In the comparison of the rates for the diarrheal diseases obtaining during the World War with those of earlier wars we are at once faced with a difficulty arising from differences in nomenclature. The last few decades have been so fruitful of discoveries in the pathology and etiology of disease and in advances in the exactness of clinical diagnosis that the significance of many a diagnostic term as understood to-day is widely different from that accepted only a short time ago. The modern conception of dysentery is that of a clinical entity or complex characterized by an increase in the number of stools, which contain pus, mucus, and blood, accompanied by abdominal pain and tenesmus. This symptom complex may be induced by several known specific agents, of which the most important are the dysentery bacilli and the Entamoeba histolytica. Of the dysentery bacilli there are several well recognized, more or less nearly related strains, and possibly other bacteria such as the paratyphoid group organisms may at times cause the same group of symptoms. Conditions permitting accurate diagnostic work, the Surgeon General accepts the diagnosis "dysentery" only when supported by evidence as to the specific causative organism. Under war conditions it usually proved impossible to carry out the laboratory studies necessary to such proof and hence by far the greater number of cases of dysentery reported during the war period were unclassified etiologically. A minority, however, were reported as of bacillary or amebic origin. Headings are found in the war tabulations for balantidic dysentery and for dysentery due to other protozoal agents.

In addition to the dysenteries properly so called, there were reported during the war a large number of cases under the headings "diarrhea," "enteritis," and "colitis," the two latter combined in the tabulations. It is self-evident on account of the clinical character of these conditions that a certain number of cases recorded as diarrhea or as enterocolitis actually may well have been dysentery, and, conversely, that some of the cases recorded as "dysentery, unclassified" might better have been called diarrhea or enterocolitis had a strict etiological classification been possible. That in general, however, the

• Unless otherwise stated, all figures for the World War period are derived from sick and wounded reports sent to the Surgeon General.-Ed.

distinction between the dysenteries and the nonspecific diarrheal diseases is a valid one on clinical grounds there can be no doubt as will be shown later. In the earlier records of the United States Army little attempt seems to have been made to distinguish accurately the different types of "intestinal flux." Diarrhea, dysentery, enteritis, and colitis, as well as other now archaic diagnostic terms, were used evidently more or less interchangeably. In the Medical and Surgical History of the War of the Rebellion,' the "fluxes" are divided into four groups: Acute and chronic diarrhea and acute and chronic dysentery. Modern diagnostic criteria were not sufficiently in use during the period of the Spanish-American War and the Philippine insurrection to make the statistics of that period much more valuable in the differentiation of the various types of intestinal disease than were those of earlier years. Indeed, in spite of increased diffusion of knowledge and of greatly increased laboratory facilities, experience during the World War has shown that under field conditions and the greater number of these cases must be expected to occur during active campaigning accurate differentiation is impossible. For this reason comparisons between the incidence of diarrheal diseases in the World War, and that in earlier conflicts must necessarily be based on totals of the entire group. Nor is this necessarily an unscientific or illogical method of comparison for, so far as may be said at present, the methods of transmission of the diseases of this group, varying as they do clinically and etiologically, are essentially the same. We believe that they are all acquired by the ingestion of infected food or drink and that consequently the underlying predisposing causes and the necessary preventive measures must be considered to be the same for all these diseases however different the specific etiology of individual cases.

Returning to the question of the nomenclature of these diseases, it is evident that in spite of the probability of some confusion in recent statistics, and of the impossibility of separating from the statistics of the past any groups comparable to those of modern tables, there can be little doubt that in the statistics of the World War the diarrheal diseases can be divided into two clinically different groups, on the one hand those which were reported as dysentery on clinical grounds and on the other those cases which were perhaps more loosely classified as diarrhea, colitis, or enteritis. The distinction between these two groups originally made by the clinicians in the individual cases is emphasized and confirmed by the study of the incidence of the two groups month by month, and by a comparison of the severity of the cases as shown by the average number of days lost from duty per case. Table 47 shows the monthly incidence rates of these diseases for the white enlisted men on duty in the United States for the period of the war. Inasmuch as these figures are not influenced by sharp variations in sanitary conditions such as occurred during operations at the front in France, they furnish a better means of comparing the varying incidence of disease than would the figures for the entire Army. The rates under the heading "Dysentery (all)" include all specifically diagnosed cases of dysentery and all cases of "Dysentery, unclassified."

With the possible exception of diarrheas believed by some to be due to chilling of the abdomen.

TABLE 47.-Diarrheal diseases. Primary admissions, white enlisted men in the United States, April, 1917, to December, 1919. Annual rates per 1,000 by months

CHART XXXVI.-The diarrheal group of diseases. Annual admission rates by months for dysentery (all), diarrhea, and enterocolitis, white enlisted men in the United States

Study of the figures given in Table 47, and the graphic comparison of the rates shown in Chart XXXVI, which is drawn from the same figures on a logarithmic scale of ordinates, leads to the conclusion that while the rates for cases classed as "diarrhea" and those for "enterocolitis" rose and fell together in almost perfect correlation, the cases classed as "dysentery" varied independently, showing not nearly so much seasonal variation, and the curve for dysen

tery is quite independent of that for diarrhea or that for enterocolitis. We are thus justified on statistical grounds in assuming that the distinction made by the reporting officers is an entirely valid one. We are further supported in this conclusion by the analysis of the severity of the average case as shown by the number of days lost from duty per case under each heading. Three thousand five hundred and forty-seven cases of dysentery in white enlisted men accounted for the loss of 99,561 days, or 28.3 days per case. There were 19,125 cases classed as "diarrhea," with 215,420 days lost, or 11.2 days per case. Enterocolitis resulted in the loss of 605,811 days among 56,865 cases, the average case losing 11.4 days from duty. It is seen that the two latter conditions were of equal severity, while the dysentery cases averaged much greater severity. It seems amply justifiable, therefore, to divide the consideration of these diseases into two groups, the dysenteries, on the one hand, and the cases reported as "diarrhea" and as "enterocolitis," on the other. Both groups are doubtless of mixed etiology. In the dysentery group we shall find some data for conclusions as to the relative importance of the recognized inciting agents in the period of the war. In the second group no specific statements as to bacterial or protozoal etiology are possible.

Table 47 shows the further interesting fact that the rates for all classes of diarrheal diseases showed a marked tendency to decrease as time passed. The highest rates were shown during the first months of mobilization, during the period of voluntary recruiting, and before the completion of the great training camps and cantonments which housed the National Army during the period of preparation. During the following year, 1918, although the camps were constantly filled with recruits as the older troops were sent to the front, the rates for these diseases showed a definite decline. This may probably be best explained by the improved environmental conditions possible in the completed camps and by the results of training in sanitary matters. However, the rates for 1919 showed a still further improvement. During this year the camps were the scene of the rapid demobilization of the Army. Men returned from abroad and passed rapidly to the camp selected for discharge. Conditions were not as favorable for maintaining a high sanitary standard as was the case in the previous year, though every effort was made to do so. It may be permissible to argue that the low rates during demobilization indicate that in the intestinal infections as in those of the respiratory tract the seasoned soldier shows a greater resistance than does the recruit.

TABLE 48.-The diarrheal diseases (dysentery, acute and chronic, and diarrhea). and deaths, absolute numbers and ratios per 1,000 per annum, white enlisted States Army, 1819 to 1919

Admissions

men, United

• For years 1819-1848, inclusive, statistics are for the year ending Sept. 30, for the years 1849-1882, inclusive, year ending June 30; for the years 1883-1919, inclusive, year ending Dec. 31.

Cholera epidemic, Black Hawk War.

No strength records available for these years.

d Covers period of Mexican War (1847-48).

• Civil War period: Ratios per 1,000 per annum for deaths, based on following strengths: 1862, 288,919; 1863, 659,955; 1864, 675,412; 1865, 645,506; 1866, 101,897; 1867, 40,183.

Years 1898-1903, inclusive, covers period of Spanish-American War and Philippine insurrection; also covers period; of the China expedition. (1900-01).

These two years (1898-99) not tabulated separately; does not inclue enteritis.

Reported as "other diarrheal diseases," but does not include dysentery and enteritis.

Previous to this year, officers were included with white enlisted men; beginning 1904 they are excluded.

i 1916 includes enteritis.

* Covers period of World War, through period of demobilization.