Innovative biosensors for the detection of microbial pathogens require selective and robust probes for target recognition. Filamentous bacteriophages, or phages, are viruses that multiply in bacterial cells. They are composed of a proteic shell, called capsid, which contains the single stranded DNA codifying for all the phage proteins and are very robust structures. A phage library is a population of genetically-modified phages, each displaying a random peptide on the capsid surface. Phages displaying target-specific peptides can be selected from the library and used as probes for biosensors. In this study, we selected phages able to recognize the protozoan parasite Leishmania infantum, which can cause a range of clinical manifestations, including visceral leishmaniasis (VL), a disease that can be fatal if untreated. Phages were evaluated in the ability to recognize and bind L. infantum-infected macrophages, with or without cell lysis. The specific interaction of the phages with whole or lysed infected macrophages was analysed by using an enzyme-linked immunosorbent assay (ELISA).