[1] Western Resere Univ, Syphil Clin, Cleveland, OH USA
[2] Johns Hopkins Univ, Syphil Clin, Baltimore, MD USA
[3] Mayo Clin, Syphil Clin, Rochester, MN USA
[4] Univ Penn, Syphil Clin, Philadelphia, PA USA
[5] Univ Michigan, Syphil Clin, Ann Arbor, MI USA