First local infection phase of early syphilis. The primary effect is a local, plasma cell-rich, painless inflammation of the skin at the site of inoculation of Treponema pallidum subsp pallidum (primary effect).
Clinically, a 0.4-0.6cm reddish papule or plaque develops 2-6 weeks (mean: 3 weeks) after infaction and is generally ignored. This ulcerates in a maximum period of 14 days. The ulcer that develops is also painless. It is surprisingly coarse indurated and spirochete-rich and thus highly contagious. In some cases, the primary effect also occurs extragenitally (mainly orally; rarely on fingers or nipples). Spread of the pathogen to the regional lymph nodes leads to swelling of the lymph nodes, which is also almost painless. Indolent regional lymphadenitis (bubo) + primary effect form the primary complex, the stage of a still regional infection by Treponea pallidum subsp pallidum.