Strategic surveillance plan for zoonotic leishmaniosis in Portugal

Leishmania infantum is a vector-borne zoonotic parasite causing zoonotic leishmaniosis across Southern European countries, with poor prognosis for immunocompromised humans or animals. Improved monitoring and control of zoonotic leishmaniosis at the level of animal reservoir is critical to support One Health coordinated responses aligned with the objectives set out in the WHO roadmap for Neglected Tropical Diseases.

We evaluate the suitability of a leishmaniosis surveillance system grounded on the network of public municipal animal shelters in Portugal (CROA), using dogs and cats as sentinels for sandfly exposure and L. infantum infection. Unowned dogs (n = 1194) and cats (n = 478) admitted at 34 CROA and four private shelters between 2021 and 2024, representing 90 municipalities distributed over six geographical regions of mainland Portugal, were clinically evaluated and serologically tested for antibodies to Leishmania parasites and Phlebotomus perniciosus salivary proteins by means of a multi-antigen enzyme linked immunosorbent assay (ELISA).

Canine (CanL) and feline (FeL) leishmaniosis seroprevalences were estimated at 11.8% and 5.0%, respectively. Serological evidence of exposure to P. perniciosus was found in 18.2% and 6.3% for dogs and cats, respectively. Significant regional differences in CanL and FeL seroprevalences were observed across the country, reflecting areas of differential endemicity. The study concluded that CROA network can substantially strengthen zoonotic leishmaniosis surveillance in Portugal, by enabling a geographically distributed sampling of animal reservoirs across multiple regions of mainland Portugal. When analysed using the proposed multi-antigen ELISA, these samples provide easily accessible, potentially useful and cost-effective epidemiological information.