Considering the growing need for a faster method to identify severe forms of leptospirosis and its treatment, and regarding the limited available data on the role of the major pro-inflammatory markers, the present study aimed to investigate the role of acute phase serum cytokines including IL-6, IL-8, IL-10, IL-12 and TNF-α concentrations in the progression of leptospirosis. This evidence concerns the gene TNF and leptospirosis.