Trypanosoma musculi: transfer of immunity from mother mice to litter.

Trypanosoma musculi infection in newborn and young CBA/J mice lasted longer and produced higher parasitemia than in adult mice. IgM, followed by IgG1 and IgG2 antibodies, appeared after 2 weeks following infection of 8-day-old mice. Baby mice that recovered from infection were immune. Mice born to normal mothers and nursed by immune ones were completely protected for approximately 1 month. Antibodies of the IgM, IgG1, and IgG2 classes were found in sera of lactating mice. Immune resistance of baby mice did not correlate with the amount of antibodies transferred from the mother either before or after birth.