It has been the experience that clinical histories, pathologic findings and the Wassermann test may indicate syphilis in many cases in which it is impossible to demonstrate the presence of T. pallidum in any of the tissues outside of the primary and secondary lesions accessible to external examination. This may in part be accounted for by the stage of the disease, the effects of treatment, and the difficulty encountered in getting the organisms present in a given preparation to reveal their presence when staining methods or silver impregnation are applied.
This disease, in both its acquired and its congenital forms, is perhaps as common on the Isthmus of Panama as elsewhere, yet it almost never happens that the demonstration of T. pallidum, either in smears or in sections, can be made from selected material taken at autopsy from the various tissues, such as liver, placenta, bone-marrow, spleen, heart, aorta, etc.
CLARK HC, GATES IN. TREPONEMA PALLIDUM FOUND AT AUTOPSY, IN THE BLOOD-STREAM AND ELSEWHERE, IN A CASE OF CONGENITAL SYPHILIS. Am J Dis Child. 1915;IX(2):126-131. doi:10.1001/archpedi.1915.04100440047003