Development and validation of a latex-based lateral flow assay for the serological diagnosis of feline leishmaniosis caused by Leishmania infantum

Background Feline leishmaniosis is a vector-borne disease caused by Leishmania infantum parasites and transmitted by infected phlebotomine sand flies. The infection is emerging and diagnostically challenging, partly because cats tend to exhibit lower and more variable antibody responses than dogs. Methods In this study, a recombinant antigen-based diagnostic platform was developed and validated for the serological detection of L. infantum infection in cats, incorporating both enzyme-linked immunosorbent assay (ELISA) and lateral flow immunochromatographic assay (LFA) formats. Results A total of 1118 feline serum samples were analyzed. Negative samples were confirmed by indirect immunofluorescence test and a recombinant antigen-based ELISA, while positive samples were defined using a dual-ELISA approach based on recombinant and crude antigens to establish a high-confidence reference set. The performance of a latex-based LFA was evaluated and compared with that of a conventional colloidal gold-based lateral flow assay. The latex-based LFA demonstrated high specificity (99.5%, 95% confidence interval [CI]: 98.9–99.8) and a markedly improved sensitivity (88.9%, 95% CI 78.4–95.4) compared with the colloidal gold-based assay (46.0%, 95% CI 33.4–58.9). Quantitative analysis of test line intensity revealed a mean 3.08-fold increase in signal with the latex-based system. Notably, a substantial proportion of positive samples missed by the colloidal gold assay were successfully identified by the latex-based platform. Conclusions These findings indicate that the combination of recombinant antigen design with optimized latex-based detection significantly enhances the performance of lateral flow assays for feline leishmaniosis. This approach represents a promising strategy for the development of more sensitive and reliable point-of-care diagnostic tools in veterinary medicine.