The Modern Classification of Dysenteries is Based on Etiology Rather than upon Clinical Manifestations
Owing to the great importance of the two main kinds of dysentery, amoebic, or that caused by Entamoeba histolytica, and bacillary, or that caused by some strain of Bacillus dysenteriae, we shall consider them separately from the other causes of the dysenteric symptom-complex.
A. Dysenteries caused by animal parasites.
Protozoal dysenteries.
1. Amoebic dysentery (Entamoeba histolytica).
2. Flagellate dysenteries (Lamblia intestinalis, Trichomonas intestinalis and Chilomastix mesnili).
While in adults these intestinal flagellates usually cause only a diarrhoea, with at times marked nervousness, they may produce dysenteric symptoms in young children. The onset in children under three years of age may be insidious and attended with fever. The stool contains much mucus with only a little blood.
In cases of amoebic dysentery, the diarrhoeal attacks, which at times occur, are often associated with an abundance of flagellates, which may well be the cause of the complication. Cases of dysenteric diarrhoea have been reported from Gallipoli in which Lamblia (Giardia) were apparently the only parasites involved. Such stools are often of a yellow ochre color. Relapses are common features of Lamblia infections. Lamblia is an inhabitant of the upper intestine while Trichomonas and Chilomastix belong to the large intestine, especially in the region of the caecum. While these last named flagellates are often found in the stools of those convalescent from dysentery there is a general opinion that they are nonpathogenic. These organisms may be present in diarrhoeal conditions in which case it is common to designate such diarrhoeas as flagellate diarrhoeas. Fantham and Porter have reported 187 cases of pure lambliasis.
In diagnosis it is important to recognize the encysted Lamblia. These are oval cysts, about 10 × 7µ and show a curved central line, with two lateral dots. When stained these dots show as chromatin areas. These cysts may be found in the faeces in great numbers. The vegetative Lamblia has 4 pairs of flagella, is about 15µ long and has a tumbling motion. Calomel alone or calomel and ipecac give good results at times. Enemata of organic silver salts may be of benefit.
Porter recommends bismuth salicylate. Low has noted the tendency of lambliasis to recur and thinks many of the reported cases of cures are only temporary. His experience with bismuth, salol, thymol and cyllin has not been encouraging.