Effects of Starvation and Lack of Bile upon Growth, Egg Production and Egg Viability in Established Rat Tapeworms, Hymenolepis diminuta

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Abstract
Sixty-nine Wistar rats were fed single cysticercoids of the rat tapeworm, Hymenolepis diminuta. Fifty-six revealed the presence of tapeworm eggs in the feces from a total of 65 rats which lived for 20 days after infection. On day 20 after infection 16 infected rats were starved, 25 infected ones had operations performed to reroute bile to the caecum via a cannulary by-pass and were subsequently retained on a normal diet, and 15 infected rats remained on a normal diet. Feces collected from 31 rats (9 starved, 15 bileless, and 7 normal) during the next 7 days were subjected to egg counts, and random samples of daily collections of eggs were offered to starved flour beetles, Tribolium confusum. After the 7-day experimental period all rats were sacrificed, and place of attachment, length, and wet weights of recovered tapeworms were recorded. Twenty days after tapeworm eggs had been offered to beetles they were sacrificed and all cysticercoids counted. Statistical analysis showed that starved rats lost weight at rates significantly different from bileless or normal; bileless and normal rats gained weight at the same rate; tapeworms in bileless hosts were more posteriorly located in the small intestine; worms from starved rats were as long as from normal hosts, but were shorter from bileless hosts; worms in bileless and starved rats weighed less than worms from normal hosts; egg output by tapeworms in bileless and starved hosts was equal, but was less than from normal hosts; and finally, although beetles had received the same number of eggs, significantly different recovery rates of cysticercoids occurred from eggs of the experimental groups.