Background: For long time, canine leishmaniosis (CanL) was considered endemic in the southern, central, and insular regions of Italy, whereas heartworm disease (HW) by Dirofilaria immitis in the northern region and in the swampy Po valley. Following the reports of new foci of both diseases, in this study we update the distribution patterns and occurrence of new foci of CanL and HW discussing the main drivers for the changes in the epidemiology of these two important zoonotic canine vector-borne diseases. Methods: Based on the statistical analyses of serological assays (n=90,633) on L. infantum exposure and D. immitisinfection performed by reference diagnostic centres in Italy over a ten-year period (2009–2019), the distribution patterns of both pathogens were herein presented along with the occurrence of new foci. Results: Results highlighted the changing distribution patterns of L. infantum vs D. immitis infection in Italy. CanL is now endemic also in the northern regions and HW has endemic foci in central and southern regions and islands.Significant differences in L. infantum exposure and HW infection prevalence among the study macroareas were detected. The overall prevalence of L. infantum exposure was 28.2% in southern Italy and Islands, 29.6% in central Italy and 21.6% in northern Italy and that of HW of 2.83% in northern Italy, 7.75% in central Italy and 4.97% in southern Italy and islands. HW prevalence significantly varied over years (χ2=108.401, d.f.=10, p<0.0001), gradually increasing from 0.77% in 2009 to 8.47% in 2016-2017. Conclusions: The new epidemiological scenarios have been discussed according to a range of factors (e.g. environmental modifications, occurrence of competent insect vectors, transportation of infected animals to non-endemic areas, chemoprophylaxis or vector preventative measures), which may affect the current distribution. Overall, results advocate for epidemiological surveillance programs, more focussed preventative and control measures even in areas where few or none cases of both diseases have been diagnosed.

Background: For long time, canine leishmaniosis (CanL) was considered endemic in the southern, central, and insular regions of Italy, whereas heartworm disease (HW) by Dirofilaria immitis in the northern region and in the swampy Po valley. Following the reports of new foci of both diseases, in this study we update the distribution patterns and occurrence of new foci of CanL and HW discussing the main drivers for the changes in the epidemiology of these two important zoonotic canine vector-borne diseases.Methods: Based on the statistical analyses of serological assays (n=90,633) on CanL and HW performed by reference diagnostic centres in Italy over a ten-year period (2009–2019), the distribution patterns of both diseases were herein presented along with the occurrence of new foci.Results: Results highlighted the changing distribution patterns of CanL vs HW disease in Italy. CanL is now also endemic in the northern regions and HW has endemic foci in central and southern regions and islands. Significant differences in CanL and HW prevalence among the study macroareas were detected. The overall prevalence of CanL was 28.2% in Southern Italy and Islands, 29.6% in Central Italy and 21.6% in Northern Italy and that of HW of 2.83% in northern Italy, 7.75% in central Italy and 4.97% in southern Italy and islands. HW prevalence significantly varied over years (χ2=108.401, d.f.=10, p<0.0001), gradually increasing from 0.77% in 2009 to values ranging from 5.19-8.47% in 2016-2017.Conclusions: The new epidemiological scenarios have been discussed according to a range of factors (e.g. environmental modifications, occurrence of competent insect vectors, transportation of infected animals to non-endemic areas, chemoprophylaxis or vector preventative measures), which may affect the current distribution. Overall, results advocate for epidemiological surveillance programs, more focussed preventative and control measures even in areas where few or none cases of both diseases have been diagnosed.