Borrelia burgdorferi colonizes the mammary glands of lactating C3H mice: does not cause congenital Lyme disease.

Transplacental transmission of syphilis causing spirochete, Treponema pallidum subspecies pallidum, from mother to child results in congenital syphilis, an ever-expanding devastating disease worldwide. Although adverse effects of untreated gestational Lyme disease, caused by a related spirochete, Borrelia burgdorferi on fetus viability and development have been observed, cases of congenital Lyme disease are not reported. In this study, we show that B. burgdorferi colonizes mammary glands of C3H mice only postpartum; however, neither transmission of these spirochetes from dams-to-pups occurs nor congenital Lyme disease is observed in pups.