Taenia spp

A feature of the research carried out on the physiology of the group is the relatively small number of species investigated - most experiments being carried out on Hymenolepis spp., Taenia spp., Moniezia spp., Echinococcus spp. and Mesocestoides spp. amongst the Cyclophyllidea, and various species of Diphyllobothriidae amongst the Pseudophyllidea. 

H. citelli, H. diminuta and H. microstoma, one of which is mitochondrial DNA (mtDNA) (394). The mtDNA of H. diminuta has been isolated (118) and has been shown to be a typical circular molecule. The characteristics of H. diminuta DNA are shown in Table 6.11. In contrast, E. multilocularis and E. granulosus produced two distinct DNA bands after fractionation in caesium chloride, but there was no evidence that the DNA from either band represented mtDNA (493). There is presumably so little mtDNA in comparison to nuclear DNA in these organisms that it is completely masked in preparations of total DNA by this method. That this is the case has been shown by a recent study (976), where a different procedure, based on the selective precipitation of nucleic acids by cetyltrimethylammonium bromide (CTAB), was employed to extract mtDNA from isolated mitochondria. Some 300 g and 50 g, respectively, of Taenia spp. and Echinococcus sp. tissue yielded approximately only 1 ng mtDNA. 

These are normally embryonated when laid so that embryonation is not affected by external environmental factors. On account of their important role in the epidemiology of cestodiasis, the effect of environmental factors has been much studied. In particular, the effect of various physico-chemical factors on the viability of eggs of Echinococcus spp. and Taenia spp. in soil, on pastures or in sewage has been extensively reviewed (82,106, 252, 253, 638,825,963,968,969). Results of some of these studies are summarised in Tables 7.7 and 7.8). 

Fig. 8.22. Jejunal villi of ruminant and non-ruminant showing paths followed by oncospheres of Echinococcus granulosus and Taenia pisiformis (and some other Taenia spp.). The larger diameter of the E. granulosus oncosphere probably enables it to reach the lymphatic before being translocated in a venule. (Reprinted with permission from International Journal of Parasitology, 1, Heath, D. D., The migration of oncospheres of Taenia pisiformis, T. serialis and Echinococcus granulosus within the intermediate host, 1971, Pergamon Journals Ltd.)...

Cyclophyllidea Hymenolepis nana, H. microstoma, H. diminuta, H. citelli, Echinococcus granulosus, E. multilocularis, Taenia spp., Meso-cestoides corti, M. lineatus. 

Mebendazole (14) The drug has been found to be active against cysts of Taenia spp. and Echinococcus granulosus in sheep, Moniezia spp. in cattle, Ci/sticerciis tmuicollis... 

An additional benzene ring on the acid part of the salicylanilide molecule gives rise to hydroxynaphthanilides with marked anthelmintic activity. Consequently, a number of l-hydroxy-2-naphthanilides have been prepared [38-40], of which 2 -chloro-l-hydroxy-4 -isothiocyanatonaphthanilide (24) was found to kill 100% of H. nana in rats at an oral dose of 7.5 mg/kg. The compound also showed high activity against H. diminuta in rats and Taenia spp. in dogs. Several other... 

Tapeworms Echinococcus and Taenia spp. Cattle, sheep and pigs... 

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