618 THE ANIMAL PARASITES OF MAN 



I. AMCEBIC DYSENTERY. 



Amoebic dysentery, due to Entamceba histolytica (see pp. 34-41), 

 is present throughout the tropical world and also occurs in temperate 

 zones. 



Walker and Sellards 1 (1913) conducted important experiments 

 with amoebae on prisoners in the Philippine Islands. They showed 

 experimentally that cultural amoebae are non-pathogenic. As regards 

 experiments with Entamceba coli, after feeding to twenty individuals 

 they concluded that E. coli is a parasite of the human intestine but 

 non-pathogenic and non-culturable. In a third series of experiments, 

 after feeding with motile Entamceba histolytica, tetragena cysts were 

 found in the stools later; when tetragena cysts were administered, 

 motile E. histolytica were present in the subsequent stools. Some of 

 the histolytica cases developed dysentery after a time. They lay stress 

 on the necessity for the frequent examination of stools in order to 

 detect carriers. The incubation period of entamcebic dysentery is 

 usually long. 



With regard to the symptomatology of amcebic dysentery, Castellan i 

 and Chalmers distinguish four types the acute, chronic, latent, and 

 mixed types. 



The acute type has an abrupt onset ; pain is felt in the lower part 

 of the abdomen, and the motions, rarely exceeding thirty daily, are 

 accompanied by much griping and straining. Blood and mucus are 

 present in the motions, and occasionally greyish material, consisting 

 of leucocytes, mucus, Charcot-Leyden crystals, amoebae, and bacteria, 

 sometimes with particles of tissue. Nausea and vomiting may occur, 

 Digestion is usually deranged. The abdomen is sunken, the liver and 

 spleen are normal, but tenderness is felt along the course of the large 

 intestine. The urine may be diminished in quantity. 



The chronic type may succeed the acute, or appear like diarrhoea, 

 the motions being faeculent and containing mucus. Between exacerba- 

 tions, constipation may occur. The number of motions may only be 

 twelve to fourteen per diem. Gangrenous complications may occur 

 at any time, and chronic dysentery may persist for many years. 



The latent type is important, as the patients, though free from 

 dysenteric symptoms, harbour amoebae and act as parasite carriers. 

 The latent condition may lead to acute attacks or to liver abscess. 



The mixed type occurs where amcebic and baciilary dysentery are 

 combined. There is much fever, nausea, and vomiting. The motions 

 are numerous and often very offensive. 



Treatment. The most modern method of treatment, due to 

 Leonard Rogers, is by emetine. According to Castellani and 

 Chalmers, it is well to relieve griping and straining by either a hypo- 

 dermic injection of morphia or by small enemata of 40 minims of 



1 Philippine Journ, Sc., B, viii, p. 253. 



