256 THE ANIMAL PARASITES OF MAN 



relating to the principal districts of Germany. According to 

 Madelung, one case of echinococcus occurs to every 1,056 inhabi- 

 tants in the town of Rostock, in the district of Rostock one to 

 every 1,283, in Schwerin one to every 5,887, and in Ludwigsort 

 one to every 23,685 ; according to Peiper (in Up:er Pomerania), 

 one case occurs to every 3,336, in the district of Greifswald one 

 to every 1,535 inhabitants. The northern districts of Pomerania 

 are more affected than the southern ones. 



Accordingly, Echinococcus is also considerably more frequent in cattle. 

 On an average in Germany 10*39 per cent, oxen, 9*83 per cent, sheep, 

 and 6'47 per cent, pigs are infected, whereas in Upper Pomerania 

 37-73 per cent, oxen, 27-1 per cent, sheep and 12*8 per cent, pigs are 

 infected; in Griefswald, indeed, 64-58 per cent, oxen, 51-02 per cent, 

 sheep, but only 4-93 per cent, pigs are infected ; in accordance with 

 these figures Tania echinococcus must be frequent in dogs in Pomerania, 

 especially in Upper Pomerania ; on the other hand, the conjecture that 

 the frequency of Echinococcus in Mecklenburg is explained by the occurrence 

 of Tcenia echinococcus in foxes has not been confirmed. 



Beyond the European Continent, Echinococcus is frequent in 

 the inhabitants of Iceland as well as in those of Australia. In 

 Iceland, according to Finsen, one person is affected with Echino- 

 coccus to every forty-three inhabitants ; according to Jonassen the 

 proportion is i : 63 ; this is due either to the habits of the people of 

 Iceland or to the frequency of Tcenia echinococcus in dogs, and the 

 prevalence of the " bladder-worm " in cattle. In certain districts 

 of Australia it is just as frequent. In Cape Colony, Egypt and 

 Algeria Echinococcus is not rare, but it is scarce in America and 

 in Asia, with the exception of the Nomadic tribes by Lake 

 Baikal. 



Echinococcus attacks persons of every age, though it is rare 

 in children up to ten years of age and in old people. It occurs 

 most frequently between the ages of 21 and 40 years. According 

 to all statistics it preponderates in women (about two-thirds of 

 the cases). The liver is its favourite seat (50 to 69 per cent, of 

 the cases) ; next, in order come the kidneys, lungs, cranial cavity, 

 genitalia, organs of circulation, spleen, &c. As a rule one organ 

 only is invaded ; multiple occurrence may originate from one in- 

 fection, or eventually from a later infection, or it may come to 

 pass that from some cause (through the spontaneous rupture of 

 an echinococcus, or the rupture of one caused by an injury or 

 surgical operation) daughter cysts, brood capsules or scolices escape 



