SOURCES AND MODES OF INFECTION. 731 



it seems very probable that in consequence of the increased commerce 

 on the shores of Lake Starenberg, the fish from which is carried as 

 far as Munich, there has arisen during the last decade a new centre 

 of infection of Bothriocephalus. It is likely that the infection was 

 carried to this district, which has recently been much visited, either 

 from Eussia or Switzerland, and that now it is itself a breeding- 

 place of the parasite. 1 It is uncertain whether the sporadic cases 

 which have been noted in London, St. Malo, Montpellier, Eome, and 

 other places on the Continent, are imported or autochthonic. 



According to the experiments of Braun, to which we have already 

 referred, it can no longer be doubted that the BotJiriocephalus is intro- 

 duced into man by eating fish, and particularly pike. It is true that 

 the danger of infection is not everywhere equally great. As may be 

 readily understood, its degree is determined by the occurrence and 

 frequency, not only of the fish, but of the host, which in its turn 

 infects the fish. The infection may also be furthered in a very high 

 degree by certain local arrangements, and particularly by those which 

 afford to the faecal masses an unhindered and speedy entrance into 

 the water, so that, as we have already seen, regular breeding-places of 

 the parasite arise, from which, in proportion to the means of com- 

 munication, it will be carried further and further by the intermediate 

 hosts. If the fish be properly prepared and sufficiently boiled or 

 fried, it may, of course, be eaten without injurious consequences, even 

 if it contain larvse of Bothriocephalus. But it is otherwise if the 

 culinary process be not sufficient to kill the latter. Smoked pike, 

 which in some places e.g., in Dorpat and its surroundings forms 

 a common article of food, is according to Braun especially dangerous, 

 being often so carelessly prepared that he has several times found in 

 the fish living larvae. The degree of temperature required to kill 

 them has not been thermometrically determined, but the fact that the 

 worms remain alive even in hard frozen pike suggests a great 

 power of resistance. We have already seen that only the pike and 

 burbot have been proved to transfer the Bothriocephalus. This, how- 

 ever, by no means excludes the possibility that other species, perhaps 

 even some of the most favourite edible fish, may yet be proved 

 equally dangerous (see p. 717). 



The oftener such fish are eaten, the greater is the danger of infec- 

 tion, and especially if little care be expended in cooking. Thus we 

 find, for example, in Dorpat, that the poorer classes, who live mainly 

 on the previously mentioned smoked pike, are the chief sufferers from 



1 Huber has recently reported an instance of the occurrence of Hothriocephalus in a 

 coachman who had never left Swabia and Lower Bavaria (Acrztliches Intelligenzblatt, No. 

 8, 1885). 



