Abstract
The primary infection of breeding female rates with N. brasiliensis was examined as an experimental model for the study of the effect of lactation on host-parasite relationships.Self-cure was inhibited when the period of infection corresponded with lactation, and a majority of worms could persist to day 34 when lactation was prolonged. A normal self-cure occurred during pregnancy, when litters were removed at birth or when the suckling litter was reduced to 3 young.