Cestode parasites

Several benzimidazoles are in use for the treatment of helminthic infections. Three of these, mebendazole, thiabendazole and albendazole, are described in this section. They have a broad range of activity against many nematode and cestode parasites, including cutaneous larva migrans, trichinosis, disseminated strongyloidiasis, and visceral larva migrans. A fourth, triclabendazole, is considered as the drug of choice for Easciola hepatica therapy. 

Siles-Lucas, M. and Hemphill, A. (2002) Cestode parasites application of in vivo and in vitro models for studies on the host-parasite relationship. Advances in Parasitology 51, 133-230. 

Fig. 9.1. Schemas showing the generalized life cycles of cyclophyllidean cestode parasite that must pass through intermediate and definite hosts and pseudophyllidean cestode parasites whose life cycle involves juvenile stages in two different intermediate hosts (the typical class of host is shown in parentheses for each life-cycle stage).

Potential Practical Impact of Vaccination Against Cestode Parasites.296... 

Lightowlers, M.W., Colebrook, A.L., Gauci, C.G., Gauci, S.M., Kyngdon, C.T., Monkhouse, J.L., Vallejo Rodriquez, C., Read, A.J., Rolfe, R.A. and Sato, C. (2003a) Vaccination against cestode parasites antihelminth vaccines that work and why. Veterinary Parasitology 1 1 5, 83-1 23. 

On the composition of intermediate hosts of cestodes, parasitic in the nine-spined stickleback. Angewandte Parasitologie, 26 147-50. 

The benzimidazoles possess weaker activity against animal cestode parasites than the nematodes. Cambendazole (5) was the first which was claimed to be effective against cestodes in sheep. This was later replaced by more effective benzimidazole anthelmintics such as mebendazole (14), fenbendazole (18), oxfendazole (19) and albendazole (20), because of their high activity and low toxicity [176]. 

Cestode Parasites Application of In Vivo and In Vitro Models for Studies of the Host-Parasite Relationship M. Siles-Lucas and A. Hemphill... 

Niclosamide [50-65-7] (2/5-dichloro-4 -nitrosahcylanihde) has been commonly used against tapeworms in small animals (5). Although tapeworms (cestodes) are frequently refractory to anthelmintics highly active against other intestinal parasites, they are sensitive to niclosamide as well as pra2iquantel [55268-74-1] and epsirantel. Pyrantel pamoate [22204-24-6] is probably the most common animal wormer used in the 1990s. 

The answer is d. (Hardman, p 1019J Niclosamide is a halogenated salicylanilide derivative. It exerts its effect against cestodes by inhibition of mitochondrial oxidative phosphorylation in the parasites. The mechanism of action is also related to its inhibition of glucose and oxyrgen uptake in the parasite. 

For many years, niclosamide (Niclocide) was widely used to treat infestations of cestodes. Niclosamide is a chlorinated salicylamide that inhibits the production of energy derived from anaerobic metabolism. It may also have adenosine triphosphatase (ATPase) stimulating properties. Inhibition of anaerobic incorporation of inorganic phosphate into ATP is detrimental to the parasite. Niclosamide can uncouple oxidative phosphorylation in mammalian mitochondria, but this action requires dosages that are higher than those commonly used in treating worm infections. 

Tapeworm. A parasitic intestinal cestode worm having a flattened, band-like form. The eggs of tapeworms are ingested by the intermediate host, they produce the larval stage in tissues. When the flesh of intermediate host is eaten, the larvae develop within the alimentary canal of the definitive host into adult tapeworms. 

Niclosamide (9.122), a salicylamide derivative, is the drug of choice for most tapeworm infestations. Niclosamide inhibits oxidative phosphorylation within the parasite, causing the cestode to be rapidly killed. 

Von Brand, T. Nylen, M. V. Martin, G. N., Churchwell, K. Composition and crystallization patterns of calcareous corpuscels of cestodes grown in different classes of hosts. J. Parasit. 53, 683 (1967)... 

Nieland, M. L, Von Brand, T. Electron microscopy of cestode calcareous corpuscle formation. Expl. Parasit 24, 279 (1969)... 

Each of the major lineages of parasitic flatworms shows remarkable adaptations to parasitism. Whilst larval forms, mode of development, mode of reproduction, life-cycle complexity, method of attachment, site of infection and host use differ enormously between the monogeneans, cestodes, aspidogastreans and digeneans, each lineage has exploited this heterogeneity to a great effect. 

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