Studies reported Eotaxin-2 [22], G-CSF [22], GM-CSF [22, 33], IFN-γ [22], IL-1β [22], IL-2 [35], IL-4 [22], IL-6 [21, 22, 26, 31, 33, 34], IL-7 [22], IL-8 [21, 23, 26, 31, 33, 36], IL-10 [21, 22, 26, 31, 36], IL-11 [22], IL-12P40 [28], IL-13 [22], IL-17 [22], IL-21 [20], IL-23 [20], IP-10 [27, 33], MCP-1 [22, 33], MIG [27], MIP-1δ [22], sTNFR1 [22], TNF-α [20–22, 31, 34, 35] and VEGF [33] as elevated among leptospirosis patients. This evidence concerns the gene IL21 and leptospirosis.