280 BACTERIOLOGY FOR NURSES 



E. Histolytica. As early as 1860 Lambl of Prague discovered 

 amebae in the stools of a severe case of dysentery. Very soon other 

 investigators reported their presence both in dysenteric and in 

 normal stools, with the result that a number of parasitic forms were 

 thought to exist. Schaudinn in 1903 clearly showed that many 

 of the forms described represented different stages in the develop- 

 ment of one organism and that practically only two intestinal 

 forms had been discovered, which he renamed E. histolytica and 

 E. coli. The latter he regarded as a harmless parasite and the 

 former as the inciter of amebic dysentery. 



Amebic dysentery differs from bacillary dysentery in that it 

 is a chronic infection of the colon which starts insidiously and 

 is characterized by relapses and recurrences. It occurs sporadi- 

 cally or in endemic form in the tropics and not unfrequently in 

 the temperate zones and in about 20 per cent of cases is compli- 

 cated by liver abscesses. Emetin administered hypodermically 

 has proved of such therapeutic value that it is accepted as a spe- 

 cific. Bacillary dysentery, on the other hand, is an infection of the 

 small intestine, has an acute onset, marked symptoms of toxemia, 

 occurs in epidemic form, usually has no sequelae, and is not influ- 

 enced by emetin. 



Amebic dysentery runs an irregular course over a period of a 

 few weeks to several years. In severe forms the stools are watery 

 and contain varying amounts of blood and mucus ; they vary in 

 number from twenty to fifty in twenty-four hours. The amebae 

 penetrate between the epithelial cells to the submucosa, multiply 

 there, and by their presence irritate the tissues. At first there 

 is an edematous local swelling ; soon the mucous membrane becomes 

 ulcerated, and gangrenous sloughs result. The ulcers thus formed 

 have an irregular overhanging border with a much larger cavity 

 in the submucosa than the opening into the mucous membrane 

 indicates. 



When liver abscesses occur as a complication they are usually 

 single and of a large size, or occasionally numerous small ones 

 may be seen. The contents usually consist of a gelatinous pink 

 fluid containing necrosed tissue, blood, and amebae. It not 



