GSTM1 and syphilis: The impact of syphilis and its treatment on renal function markers (serum creatinine, GFR), liver enzymes (gamma‐GT, ALT, AST), inflammatory parameters and blood count (CRP, Hb, LDH) and immune response (leucocytes, CD4 count, CD8 count, CD4/CD8 ratio) was investigated three to six months before, at time of syphilis diagnosis, and three to six months after treatment.