Also, participants who acquired syphilis had significantly lower levels of seminal MCP-1 at baseline than those who did not acquire syphilis (median 1,141.6 pg/ml [IQR: 819.02046.4] compared with 2,436.4pgI/ml [1084.5–5339.4], p = 0.01, Fig 2B). This evidence concerns the gene CCL2 and syphilis.