Isolation of Leishmania infantum from a red fox (Vulpes vulpes) and vector competence of Phlebotomus perniciosus

Red foxes (Vulpes vulpes) have been reported as potential reservoirs of Leishmania infantum in the Mediterranean region; however, their capacity to infect sand fly vectors has not been previously demonstrated. Here, we isolated L. infantum from lymph node aspirates of a naturally infected red fox and, for the first time, performed xenodiagnosis in this wild canid species using Phlebotomus perniciosus sand flies. Promastigotes were detected in the guts of 92.1% (n = 151/164) dissected sand fly females, with a heavy parasite load observed in 58.9% (n = 89/151) and moderate in 27.1% (n = 41/151). Parasites retrieved from sand flies were molecularly confirmed as L. infantum. Isolation from the lymph node aspirate was successful, with promastigotes first detected after 4 days of culturing, followed by a marked increase thereafter. These findings demonstrate that L. infantum can persist and visceralize in red foxes and that symptomatic foxes could be highly infectious to P. perniciosus. Collectively, the results support the role of red foxes as reservoirs of L. infantum in endemic areas and highlight their relevance for disease control programs within a One Health framework.