Echinococcus adult worm

A virtually untapped area for studying diversity in Echinococcus is the use of microsatellite DNA. Some microsatellite markers are available for E. multilocularis, following the earlier studies of Bretagne et al. (1996) who were able to use microsatellite DNA to divide isolates of E. multilocularis into three groups European, North American (Montana) and Japanese. More recently Nakao et al. (2003) isolated two microsatellite loci that were used to demonstrate population-level polymorphisms in E. multilocularis adult worms derived from wild red foxes collected from a limited geographical area of Hokkaido, Japan. 

Fig. 9.5. Scolex of Echinococcus granulosus in the duodenum of the dog tissue fixed rapidly with hot Zenker s fluid. The rostellum is extended into a crypt of Lieberkuhn with the hooks lightly penetrating the epithelium, some cells of which have become flattened and destroyed. The adult worm must therefore be considered to be both a tissue and an intestinal parasite.

HOST-PARASITE SPATIAL RELATIONSHIP The surface topography of intestinal and tissue sites is usually elaborate and difficult to reproduce in vitro, as are the spatial relationships between the adult worms and the mucosa. These relationships have been shown to be especially important in some species (e.g. Schistocephalus, Ligula, Echinococcus), for, if they are not reproduced within reasonable limits in vitro, insemination may not take place (See Fig. 10.2). 

This is one of the most serious tapeworm infections caused by the hydatid cysts, formed by the larval stage of Echinococcus granulosus and E. multilocularis in man and domestic animals. The disease is prevalent wherever man is closely associated with cats, dogs and sheep. The adult worms live in the alimentary canal of the definite host (cats, dogs, wolves, foxes and jackals) and shed eggs from gravid pro-... 

Infections with helminths, or parasitic worms, affect more than two bilhon people worldwide. Pathogenic worms are classified into roundworms (nematodes) and two types of flatworms, flukes (trematodes) and tapeworms (cestodes). Immature forms invade humans via the skin or gastrointestinal (GI) tract and mature into adult worms with characteristic tissue distributions. With few exceptions, such as Strongyloides and Echinococcus, they cannot complete their life cycle and replicate themselves within the human host. 

Fig. 10.7. A stationary lift for the in vitro cultivation of adult Echinococcus granulosus, from protoscoleces. By use of cellulose tubing, the circulating medium is separated from the medium in the lower flask with the result that the interface between the worm and the solid substrate remains undisturbed nutrients and waste materials can be exchanged via the cellulose membrane. Up to six such systems can be connected to a single gas pipeline. (After Smyth, 1969.)...

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