The objectives of our study were to evaluate the sensitivity and specificity of the commercially available Serion ELISA classic Leptospira IgM using the MAT as imperfect reference test with patient sera from confirmed leptospirosis cases, blood donor sera, with sera from patients with other infections than leptospirosis (all European) and sera from a cross-sectional study in the indigenous population called “Wiwas” of the Sierra Nevada de Santa Marta, North-east of Colombia. This evidence concerns the gene CD40LG and infection.