Transmission of syphilis
There T. pallidum (syphilis) quickly perishes outside of the body, an infection presupposes the direct transition from one organism to the other, i.e. through contact with the mucous membrane of all kinds, most often through Sexual intercourse.
The pathogen can also enter the new host through the uninjured mucous membrane, whereby contact with the mucous membrane of less than a minute can be sufficient. About the injured skin the pathogen can also penetrate, but not through the uninjured one. The risk of transmission through contact with an infected person is believed to be 30-60%. Patients are highly infectious Stage I of syphilis, here is the risk of transmission 100%. In stage II of syphilis, the patients are infectious and in stage III it persists despite severe symptoms no risk of infection (no transmission) more. You can find more information about the individual stages at: Syphilis symptoms
The main sources of infection are the weeping ones Skin changes the early secondary stage in diseased sexual partners, they contain plenty of pathogens. Non-sexual transmission is also possible, e.g. B. by a kiss, at Obstetricians, Dermatologists (Dermatologist) or through Blood transfusion. Additionally is T. pallidum crosses the placenta, i.e. the bacterium can pregnancy about the placenta or at the birth of the blood circulation get into the child's bloodstream from the mother and infect the child.
More on this topic at: Infections in pregnancy
A single bacterium is likely to be sufficient for infection / transmission.
After the bacterium has penetrated, the body spreads and becomes infected in the stages Incubation, Generalization and Organ manifestation. When incubating it penetrates T. pallidum due to its mobility actively into the tissue and forms a primary complex with swollen regional Lymph nodes. During generalization, the bacterium spreads through the bloodstream (hematogenous). It is assumed that T. pallidum an enzyme can loosen the walls of small arteries so that it can better penetrate the vessel. This leads to inflammation and narrowing of small arteries, which leads to an insufficient supply of the tissue with oxygen and thus to death (necrosis) of the tissue. This organ manifestation shows up in the secondary and tertiary stages.