Canine leishmaniosis on Favignana Island: a prospective observational study on infection dynamics, clinical outcomes and field safety in dogs receiving both vaccination (LETIFEND®) and an antifeeding collar (SCALIBOR®)

Abstract Background Canine leishmaniosis (CanL) is endemic in Italy and is an important veterinary and public health concern. Integrated preventive strategies combining vaccination and vector control are recommended in endemic areas, and field data supporting the safety and effectiveness of this concurrent use are limited. Methods A longitudinal field study conducted on Favignana Island (Sicily, Italy) evaluated the concurrent use of a vaccine (LETIFEND ® , Leti) and sandfly repellent collar (SCALIBOR ® , MSD Animal Health). Client-owned dogs (154) were prescreened by clinical examination, serology, quantitative polymerase chain reaction (qPCR) and serological testing (SNAP ® 4Dx ® Plus, IDEXX). Leishmania -negative dogs (62) were enrolled in the study, vaccinated, fitted with a deltamethrin-impregnated sandfly repellent collar, and monitored every 6 months for 24 months (2 transmission seasons). Follow-up evaluations included clinical examination, serological testing (SNAP ® Leish ® Test, IDEXX), and conjunctival swab qPCR; sera were stored for subsequent indirect immunofluorescence antibody testing (IFAT). After 12 months, dogs that remained negative received a booster vaccination and replacement collar. Results The proportion of dogs positive for CanL in the prescreen was 12.3% (19/154). Two dogs in the enrolled group (3.22%, 2/62) developed clinical signs compatible with CanL and tested positive (SNAP ® Leish ® ,IDEXX) during the study. IFAT testing of enrolled dogs found low antibody titres in nine additional clinically healthy dogs corresponding to a cumulative infection incidence of 14.5% and an incidence density of 0.61% per dog-month. No local or systemic adverse reactions associated with the combined preventive protocol were recorded. Conclusions Concurrent vaccination (LETIFEND ® , Leti) and preventive collar administration (SCALIBOR ® , MSD Animal Health) resulted in no adverse events, although there was a low incidence of clinical CanL and seroconversion over two consecutive transmission seasons. These findings support the use of integrated preventive strategies to limit the development of clinical disease in dogs living in endemic areas.