AMCF:BIC DYSENTERY.—This affection is also known as endemic and tropical dysentery, and as amebic enteritis. It is characterized clinically by irregular diar rhcea, a variable course often marked by periods of intermission and exacerbation; a special tendency to chronicity, and the development of liver-abscess, and ana tomically by ulceration and thickening of the large intestine.
Morbid Anatomy and Etiology.—This form of dysentery has been known ana tomically for more than a century: since the writings of John Hunter, who ob served the disease in Jamaica. The prin cipal contributions npon its pathology has been made by Councilman and La fleur,Kruse and Pasquale,Kartulis, How ard and Hoover, Flexner and Harris.
The lesions in the intestine are of two kinds: (1) a general catarrhal inflamma tion of the large gut, which does not dif fer from catarrhal colitis due to other causes; (2) the specific focal lesions (ul ceration) caused by the presence in the tissues of the amooba coli. The specific lesions are located oftenest in the sigmoid flexure, somewhat less often in the efecum and ascending colon, and more rarely in the descending and transverse colon and rectum (Kartulis). The verm iform appendix may be the seat of ulcera tion; most rarely does the dysenteric process pass beyond the ileo-cTcal valve and attack the lower end of the ileum.
The amcebx are present upon the sur face of the intestine and in the interior of the crypts, where by continued irri tation they bring about destruction of the epithelium; they may then be ob served to penetrate through the inter glandular tissue into the depth. They set up an active inflammation in the mucosa, shown by the hyperminia, ec chymosis, and swelling of the glandular epithelial cells. The farther extension of the amceba takes place after the par tial destruction of the muscularis mu cosre. The organisms now reach the submucosa, where the principal damage is inflicted. The number of amcebre in the submucosa is considerable; their presence excites a reactive inflammation, and soon a solution of the tissues in which lie. Thus a cavity is formed
which, sooner or later, is followed by ne crosis and removal of the overlying mu cous membrane. When this happens, an ulcer is the result. The lymphoid folli cles are not especially attacked; they simply share the fate of the surrounding tissue. The muscular coat offers some resistance; it is not generally destroyed, but the amcebm pass through it in cer tain places, enter the intermuscular tis sue, and there repeat the part they play in the submucous tissue; the structures overlying the infiltration, deprived of their nourishment, undergo necrosis. The ulcers increase by this continual process of undermining; but the typical course and appearance of the ulcer may be coinpletely changed through the ac tion of the bacteria in the intestinal canal.
The ulcers are, for the most part, un dermined. Often the defect in the mu cous membrane is small and altogether inconsiderable, while the cavity in the submucosa and deeper tissues is large, and sinuous tracts, sometimes connecting several ulcers, are met with. Again, sim ple ulcers, with little or no undermining of the mucous membrane and limited to the submueosa, exist. Both forms may be associated. More rarely still, large sloughs, which may- consist of the mu cous or muscular coats, are encountered. The part of the intestine involved be comes much thickened, partly through the infiltration present in the submucous and other coats, and partly in virtue of a thickening of the peritoneal coat; ad hesions between adjacent intestinal loops and deformation also occur. According to Councilman, fibrinous exudation upon the surface of the mucous membrane (diphtheritic or croupus membrane) does not take place in uncomplicated cases, while Kartulis describes its occur rence.
The aincebm occur in greater or less numbers in intimate association with the ulcers and even in adjacent parts. They are found in the tissue-spaces, within the crypts of Lieberkuhn, in definite lym phatic vessels, and in the veins.