Vertical transmission of Treponema pallidum to various litters and generations of guinea pigs

The transmission of congenital syphilis was studied in a 4-generation guine a pig family with 10 litters and 38 offspring. By use of one or all of the following tests (ELISA-IgM, polymerase chain reaction, and rabbit infectivi ty), transplacental infection was demonstrated through 5 litters and up to 4 generations. Twenty-eight (93%) of 30 animals were positive by greater th an or equal to 1 test, and 2 (7%) were negative by 1 or 3 tests. While tran smission of the pathogen appeared to be unaffected by the maternal acquisit ion of immunity, signs of smoldering infection in the young was suggested b y the decline in humoral responses in successive progeny and by unusual rab bit infectivity test results. With each pregnancy there was a remarkable bo oster in the maternal humoral response, which dropped significantly prior t o term. These findings shed new light on the understanding and interpretati on of serologic testing during pregnancy and the perinatal period.