58 DIPHYLLOBOTHRIUM LATUM 



B. Order Pseudophyllidea 



Cestodes with one or two groove like suckers on the scolex; 

 without proboscis or rostellum; vitellaria are numerous and 

 follicular; a uterine pore present; reproductive organs do 

 not atrophy as the uterus develops; whole segments are not 

 given off when ripe as in the members of the other group; 

 eggs oval with operculum; onchosphere surrounded by 

 ciliated membrane. 



Diphyllobothrium latum (Dibothriocephalus latus) is the 

 most important human tapeworm of this group. Three 

 other species of the Pseudophyllidea, D. cordatus, D. parvus 

 and Diplogonoporus grandis, which are probably only inci- 

 dental in man have been described. Three larval forms 

 of this group (plerocercoids) Sparganum mansoni, Sparganum 

 baxteri and Sparganum proliferum have been reported from 

 the tissues of man. 



Diphyllobothrium latum (Dibothriocephalus latus), (Plate 

 VII, Fig. 3 e, /), or the fish tape worm. Length 2 to 9 

 meters; 3,000 to 4,200 proglottids; scolex almond-shaped, 

 2 mm. to 3 mm. in length with two deep suctorial grooves; 

 proglottids except in posterior third of strobila broader 

 than long; vagina and cirrus open close together on mid- 

 ventral surface; uterine pore just behind other genital pores; 

 eggs given off constantly after maturity and not stored in 

 the uterus; ciliated larva from egg swims freely in water and 

 invades a small crustacean Cyclops developing into a 

 procercoid ; further development into plerocercoid in muscles 

 of fresh-water fish; man gets infestation by ingesting plero- 

 cercoid from raw or partly cooked fish; adult lives in the 

 intestine of cat, dog, fox and man; sometimes produces 

 severe anaemia; centers of distribution are French Switzer- 

 land, and the Baltic Provinces of Russia; found also in 

 Italy, Scandinavia, Finland, Turkestan, Japan, Africa, 

 Madagascar and North America. 



