Concurrent infections of Hymenolepis diminuta and Trichinella spiralis in the rat intestine.

The intestinal distribution of Trichinella spiralis and Hymenolepis diminuta in rats was studied in single and concurrent infections. Results showed that the location of T. spiralis was not significantly changed in concurrent infections, but higher populations of T. spiralis in single and concurrent infections resulted in a posterior shift in position. Trichinella spiralis affected H. diminuta distribution significantly by causing a posterior shift in the position of scoleces and biomass and a loss of circadian rhythm. Infection with 4,000 T. spiralis larvae resulted in decreased tapeworm weight and fecundity, and destrobilation of H. diminuta from day 8 to 18 of the T. spiralis intestinal stage. Hymenolepis diminuta moved anteriorly to its preferred microhabitat as the T. spiralis intestinal stage decreased.