Effects of host age on infection of ICR mice with Echinostoma caproni or E. trivolvis.

There was no significant difference in the number of E. caproni recovered 21 days post-infection from 1-, 2-, 4-, 5-, 6-, 7-, 12-, or 21-month-old ICR mice infected with 25 metacercarial cysts. A range of 10.8-17.3 worms was recovered from mice in the age groups. In a similar experiment with E. trivolvis, there was no significant difference in worms recovered in young vs old mice. A range of 0-1.7 worms was recovered from mice in each age group. Contrary to a previous study on E. caproni in NMRI mice, our results indicate that host age does not affect establishment of E. caproni or E. trivolvis in the ICR mouse.