The identification of risk and essential elements along the strobila of the rat tapeworm Hymenolepis diminuta.

The rat tapeworm Hymenolepis diminuta can bioconcentrate several elements to conspicuously higher concentrations than tissues of their definitive host. The main aim of this study was to locate parts of the tapeworm into which lead, cadmium, zinc, copper, manganese and iron are accumulated. Male Wistar rats were experimentally infected with H. diminuta and worms were exposed to two different forms of lead for 6 weeks through the oral exposure of their rat hosts. After the exposure period, the element levels were determined in the posterior and anterior proglottids of the tapeworm. In all cases, lead concentrations were higher in the anterior parts than the posterior parts. Concentrations of cadmium, copper, iron, manganese and zinc were also significantly higher in the anterior parts. Zinc concentrations showed an opposite trend, with higher zinc levels detected in the posterior part of the strobila, in the control group. The present study demonstrates that risk and essential elements are accumulated mainly into the anterior part of H. diminuta.