At the time the causative agent was unknown but it was well known that it was spread sexually and also often from mother to child. Its association with sex, especially sexual promiscuity and prostitution, made it an object of fear and revulsion and a taboo. The magnitude of its morbidity and mortality in those centuries reflected that, unlike today, there was no adequate understanding of its pathogenesis and no truly effective treatments. Its damage was caused not so much by great sickness or death early in the course of the disease but rather by its gruesome effects decades after infection as it progressed to neurosyphilis with tabes dorsalis. Mercury compounds and isolation were commonly used, with treatments often worse than the disease.There is some evidence to suggest that syphilis was  a common childhood skin disease in the Old World, and did not originate in the New World. According to this hypothesis, syphilis was a mostly benign infection like chicken pox which for thousands of years had been common among the young who transmitted the disease among themselves—and as adults, they gained immunity and could not be reinfected. Once living conditions in Europe began to change and certain social classes began to practice greater hygiene, syphilis was driven out of the age group in which it was harmless.
False positives can also occur with lymphoma, tuberculosis, malaria, endocarditis, connective tissue disease, and pregnancy.Because of the possibility of false positives with nontreponemal tests, confirmation is required with a treponemal test, such as treponemal pallidum particle agglutination (TPHA) or fluorescent treponemal antibody absorption test (FTA-Abs). Treponemal antibody tests usually become positive two to five weeks after the initial infection. Neurosyphilis is diagnosed by finding high numbers of leukocytes (predominately lymphocytes) and high protein levels in the cerebrospinal fluid in the setting of a known syphilis infection. Direct testing
Dark field microscopy of serous fluid from a chancre may be used to make an immediate diagnosis. Hospitals do not always have equipment or experienced staff members, and testing must be done within 10 minutes of acquiring the sample. Two other tests can be carried out on a sample from the chancre: direct fluorescent antibody (DFA) and polymerase chain reaction (PCR) tests. DFA uses antibodies tagged with fluorescein, which attach to specific syphilis proteins, while PCR uses techniques to detect the presence of specific syphilis genes. These tests are not as time-sensitive, as they do not require living bacteria to make the diagnosis. Prevention
Vaccine
As of 2018, there is no vaccine effective for prevention. Several vaccines based on treponemal proteins reduce lesion development in an animal model but research continues. Sex
Condom use reduces the likelihood of transmission during sex, but does not eliminate the risk.