THE TAPEWORM LARV.E 



201 



develop in almost an}- mannnal to which the}' find access. The hog, 

 however, is the most common host, and, from the point of view of public 

 health, the most important. 



As has been noted, the cysticercus of Tcenia solium (Cysticercus cel- 

 lulosce) is a more dangerous parasite than that of T. saginata, as it may- 

 lodge in organs such as the brain or eye with serious consequences. 

 Man can readily become a victim by auto-infection from his own armed 

 tapeworm, the eggs of which may reach his stomach by way of the 

 pyloris, or in being conveyed to the mouth by unclean fingers. By the 

 latter means, moustache twirlers and nail biters are especially exposed. 



Fortunatel}', the United States is favored by the rarity of the pork 

 tapeworm and consequently its cysts. Pig measles is most prevalent in 



Fig. 112. — Stages in tapeworm larval development: a, six-hooked larva K;"| 

 (hexacanth or onchosphere) of Taenia solium; b, cystic stage of same; c, same p-.^ 

 with head evaginated; d, ciliated larva of Diphyllobothrium latum; e, plero- \J 



cercoid of same — all enlarged (after Boas, by Kirkaldy and Pollard, from 

 Lcuckart). 



districts of foreign countries where Ijad hygienic conditions pi-evail; 

 where pigs are kept near dwellings, and their flesh is eaten raw or im- 

 perfectly cooked, conjoined with the practice of depositing human 

 excrement in the open or spreading it upon the fields as fertihzer. In 

 countries where sanitary control is of a more advanced standard the 

 prevalence of the ])ork tapeworm has been greatly- reduced. 



Location and Appearance. — The muscles most often invaded by the 

 cysts are those of the tongue, neck, and shoulder, then, in order of 

 frequencA', the intercostals, abdominal, psoas, the muscles of the thigh, 

 and those of the posterior vertebral region. Organs less often infested 

 are the liver, kidneys, heart, lungs, brain and eye. 



While the cysts may be scattered and few in number, the}^ are, on 

 the other hand, sometimes present in certain locations in enormous 

 numbers. Kuchenmeister in one case found one hundred and thirtA'- 



