PASSIVE TRANSFER OF IMMUNE SERUM REDUCES THE L1 ADULT RATIO OF WORMS RECOVERED FROM THE INTESTINES OF STRONGYLOIDES STERCORALIS-INFECTED GERBILS/

In Strongyloides stercoralis-infected gerbils it had been observed pre viously that the ratio of first-stage larvae to adult worms decreases after 3 wk of infection. Serum obtained from gerbils after this decrea se in fecundity, but before worms were expelled, was transferred passi vely to other infected gerbils during the peak of worm fecundity. The immune serum caused a significant decrease in the L1/adult ratio but h ad no effect on the number of uterine eggs, the length, or the intesti nal and ovarian ultrastructure of adult worms. Apparently a factor(s) in the immune serum either killed eggs, after oviposition, or the hatc hed larvae, without damaging the adult worms.