46 TROPICAL MEDICINE AND HYGIENE 



be the only symptom and steady permanent convales- 

 cence occur. Death may occur from cachexia and 

 anaemia. The fatal cases in Singapore died of inter- 

 current disease. The eggs in size and shape are not 

 unlike ankylostome eggs. The numerous yolk-masses 

 in the eggs as seen in the tissues should distinguish them 

 from any of the nematode eggs, and in the faeces the 

 presence of a ciliated embryo, which is liberated on the 

 addition of water, would probably prevent any mistake. 



GENERAL EFFECTS OF TREMATODE INFECTIONS. 



Increasing observation is showing that trematode infec- 

 tions are of more importance and more general in the 

 Tropics than was thought formerly. The fact that 

 lesions are produced even if no direct symptoms are 

 caused cannot be ignored. 



GENERAL PROPHYLAXIS. 



The detailed knowledge of the life-history of the inter- 

 mediate hosts, if there are any, would be of great value 

 and show the lines on which prophylactic measures 

 should be based. Thrifty races like the Chinese are not 

 likely to abandon the use of human excrement as manure, 

 and the measures that can be economically adopted in the 

 preparation of the human excrement as manure do not 

 destroy the eggs in all cases. 



Only the first stage, the escape of the miracidium, in 

 the development of the Schistosomidae is known, and 

 there is no sufficient reason to assume that a mollusc is 

 the intermediate host, if there is any. That assumption 

 of an intermediate host, mollusc or fish, is justifiable in 

 the Fasciolidae. 



An examination of the snails and fish in padi fields 

 is required to find the species of the intermediate hosts. 



It is in the liver of the snails that the rediae develop, 

 so that by breaking off the apex of the shells and teazing 

 out the liver of the snails, the infection can be detected 

 on microscopic examination. The species of snail or fish 

 and its life-history shonld also be determined. 



