EN
Cross-resistance between Toxocara canis and Trichinella spiralis was studied in CBA/J mice exposed to varying doses of T. canis and 14 days later challenged with 400 larvae of T. spiralis. Intestinal burden of T. spiralis on day 7 post infection (PI) in mice given 25 ova of T. canis was 70% of challenge control burden, but in mice given 250 ova the burden was consistently below 20% of the control value. Male worms were preferentially expelled from mice exposed to T. canis. Recovery of muscle larvae was reduced in mice given 250 ova, but not in mice given 25 ova. Intestinal burdens of T. spiralis in T. canis-sensitized mice (250 ova) was 58% of the control values at 36 h PI, and most of the remaining worms were expelled between 5 and 7 days PI. Worms from mice given 250 ova released lower numbers of newborn larvae in vitro.