Course of infection with enteric parasites in hosts shifted from enteral to total parenteral nutrition.

UNLABELLED: Two groups of rats were kept on an oral diet after infection with 10(4) Trichinella spiralis or 10 Hymenolepis diminuta larvae. Sixteen days and 2 days after infection with H. diminuta and T. spiralis, respectively, 8 rats from each group were switched to intravenous (iv) alimentation, while the remaining animals were retained on oral nutrition as controls. Rats were killed during the following 21 days. The number of T. spiralis recovered from iv-fed rats was significantly higher than in controls, whereas the sex ratio and worm size were similar. Disaccharidase deficiencies normally associated with either infection or parenteral feeding were additive in the infected, parenterally nourished rats. The rise in peroxidase activity normally associated with intestinal trichinosis was not as great (P less than 0.05) in iv-fed rats. Intravenous feeding did not affect tapeworm number, but caused destrobilization. This was followed by secondary proglottization that led to development of worms of normal length and with gravid segments, but with an increased length: weight ratio.

CONCLUSIONS

oral food deprivation in the host does not adversely affect development of established T. spiralis. The larger worm burden in iv-fed rats may be due to reduced inflammation normally involved in worm expulsion. Exogenous food in the gut is not necessary for maintaining established H. diminuta; factors necessary for sustenance and growth can be acquired by the worm entirely from the exocrino-enteric circulation.