02 TROPICAL MEDICINE AND HYGIENE 



T^NIA. 



Tcenia. A large group, which includes the common 

 tapeworms found in man. The openings of the genital 

 pores are not all on the same lateral margin, but are 

 irregularly alternate (fig. 24, A). Tests are numerous. The 

 intermediate hosts and definitive hosts both belong to the 

 Mammalia. 



The armature of the scolex varies ; in some the hook- 

 lets persist throughout adult life, e.g., Tcenia solium. In 

 others there are no hooklets in the adult scolex, e.g., 

 T. saginata, and these are sometimes known as unarmed 

 tapeworms. They all have the four suckers and rostellum. 



T. solium is a large tapeworm, 2 to 3*5 metres in 

 length. There are some 800 proglottides. The ripe 

 proglottis is usually 10 to 12 mm. in length and 5 to 

 6 mm. in breadth. The uterus has about ten lateral 

 diverticula and often less. In the younger segments the 

 vagina passes through the ovary on the same side (fig. 32) 

 on its way to the genital pore. The rostellum is 

 surrounded at its base by a double circle of hooklets. 

 It is not widely distributed in the Tropics, as the inter- 

 mediate host is the pig, and therefore in Mahomedan 

 countries man has few opportunities of acquiring the 

 parasites. In non-Mahomedan tropical countries, such 

 as China and South Africa, where pigs are freely eaten, 

 this tapeworm is common. In non-tropical regions it 

 is most common where imperfectly cooked pork is 

 eaten, as in Germany. In many people the presence of 

 tapeworms produces ill-health, and often a neurasthenic 

 condition. 



Man can act as the intermediate host as well as the 

 definitive host of T. solium. This occurrence is most 

 frequent where human excreta are used for manure, as in 

 China, but may occur whenever the ova are introduced 

 into the stomach. Auto-infection is believed to occur as 

 a result of regurgitation of ripe segments from the intestine. 

 The cysticercus, when it occurs in man, is often subcu- 

 taneous, and then forms a rounded visible swelling, 



