I40 INFECTIOUS AND PARASITIC DISEASES. 



The adult form of this cestode is found in 

 T^NiA EcHi- the dog, wolf, jackals, etc. Man harbors 

 Nococcus. the larvae. Infestment is practically only 

 encountered where dogs are kept in close 

 relationship with their masters, as in Iceland and 

 Australia. In other countries sporadic cases are 



occasionally reported, usu- 

 ally in foreigners, v/ho prob- 

 ably contracted the disease 

 elsewhere. The adult worm 

 /f P"^ WHW^ ^^ ^ ^^^^ cestode from 2.5-5 

 \\> ^i ^^BBW ^^illii^^ters in length, with 

 V flfel ^Hfflllr a head provided with four 



cup-shaped suckers and a 

 double row of booklets. 

 When man ingests the ripe 

 ova of this worm, visceral 

 infestment {Echinococcus 

 disease) ensues. Localiza- 

 tion may be in any organ, 

 the liver, lungs, kidney, 

 etc. Huge cysts enclosing 

 numerous other cysts are 

 stages in the developraent of 

 the embryos, countless numbers of which may develop 

 from a single (:^gg, thus differing from the cysticercus of 

 other cestodes in that a single egg gives rise to only 

 one embryo. 



Fig. 17. — TcBnia echinococcus: 

 a, adult; h, head from echinococcus 

 cyst. On left a detached hooklet, 

 as seen in fluid from cyst. (Coplin 

 and Bevan, after Leuckart.) 



