Serosurvey of Leishmania infantum in equids in different European countries

Leishmaniosis is a vector-borne and zoonotic disease with major sanitary implications at global scale. In Europe, Leishmania infantum is the only endemic etiologic agent, which has been previously reported in a wide range of mammal. However, the information about the role of equids in the L. infantum epidemiology is limited. We aimed to assess the seroprevalence and identify potential risk factors associated with L. infantum seropositivity in equine populations across several European countries. A total of 1364 equids, including 1005 horses, 240 donkeys and 119 mules/hinnies from Spain, Italy, United Kingdom and Ireland were sampled between 2011 and 2023. The overall seroprevalence of L. infantum was 9.8 % using indirect immunofluorescence test. A significant higher prevalence of anti-L. infantum antibodies was found in donkeys (27.9 %) and mules/hinnies (21.1 %) compared to horses (4.0 %). By country, significantly higher seropositivity was detected in equids from Italy (17.7 %; 70/395) compared to Spain (11.2 %; 63/561), while no positivity was found in animals from Ireland and UK. Our results indicate a moderate and heterogeneous spatial circulation of L. infantum in equids from southern Europe. The variable 'species' (donkeys and mules/hinnies) was identified as risk factor associated with L. infantum seropositivity. This survey constitutes the largest seroepidemiological study evaluating the circulation of L. infantum in equids at global scale. Additionally, we report for the first time L. infantum exposure in mules/hinnies in Europe. Our findings suggest the potential role of equids in the L. infantum epidemiological cycle in southern Europe and the need to implement specific surveillance programs in these species.