Development and evaluation of polyclonal antibody-based antigen detection ELISA and dot blot assays as a less costly diagnostic alternative for pathogenic Leptospira infection.

Leptospirosis is an infectious, zoonotic disease of worldwide distribution, the cause of which is infection by pathogenic Leptospira. In Chile, dairy cattle are recognized a significant source in the maintenance and transmission of this infection, which causes economic losses and represents an infection threat to workers in the dairy industry. The infection is underestimated in cattle, due to the lack of clinical, pathognomonic signs, as well as the low efficiency of current diagnostic techniques. In this study, we developed antigen ELISA and dot blot assays, based on polyclonal antibodies, to detect pathogenic Leptospira in the urine samples of dairy cattle. The proposed tests showed an acceptable diagnostic accuracy, based on an analytical sensitivity of 1·104 Leptospira per mL for ELISA, and 3.2·103 for dot blot. These results corresponded with those obtained by qPCR, and the use of urine samples allowed us to propose new diagnostic alternatives for pathogenic Leptospira infection at a low cost, which can provide information on active infection status, which is a key element in control programs both at individual and herd level.