ECHINOCOCCUS 71 



do not contain scolices. The commonest situation for 

 these tumours is in the liver, but they are not uncommon 

 in the peritoneum, lungs, brain and elsewhere. 



The adult tapeworm grows and matures rapidly, the full 

 development, from the time the scolices are ingested by 

 the dog to that in which the terminal segment becomes 

 mature and eggs are passed with the faeces, is only forty 

 days. 



FlG. 38. Section through an Echinococcus cyst with brood-capsules. 

 (From a wax model.) 



The eggs may be deposited on vegetables, and it is 

 probable that this is the common way in which infection 

 occurs in man in Australia, but where dogs are kept 

 about a house there are many ways in which the eggs 

 may be ingested by man. The time required for the 

 development of the cysticercoid tumours is much longer ; 

 two or three years is a comparatively short period, and 

 the tumour may continue to increase for many years. 



Treatment is necessarily surgical. Aspiration is not 

 advisable ; the cyst should be opened and drained. Very 

 strict antiseptic precautions are necessary, and as there 

 is usually no immediate danger it is advisable that such 

 operations, whether on the liver, lungs, or brain, should 

 only be undertaken where such precautions are practicable. 



The diagnosis has to be made from other tumours in 

 the same regions. It is only when the cysts are in con- 

 tact with the parietes that the " hydatid thrill " can be 

 obtained, or that we can be sure of the fluid nature of 

 the tumour. 



