Leishmania infantum and Dirofilaria immitis infections in Italy, 2009-2019: changing distribution patterns

Abstract

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.

Leishmania spp. in Squamata reptiles from the Mediterranean basin

“…Indeed, the detection of samples (i.e., blood, heart, liver) positive to L. infantum using kDNA specific qPCR (Francino et al., 2006), which is routinely used in endemic areas of CanL, suggests recent infections with a low parasitic load. In addition, positive samples to this protozoan species were detected in reptiles from dog shelters and island environments, which are known to be endemic for CanL (Otranto et al., 2017; Mendoza‐Roldan et al., 2020b). These areas share similar characteristics such as concentrated populations of dogs and cats, high abundance of sand flies and reptiles.…”

“…This sympatric occurrence of reptiles, domestic animals, and humans may facilitate the transmission of parasites and pathogens among them by predation, direct contact, or by vectors, such as in the case of Leishmania spp. (Mendoza‐Roldan et al., 2020b).…”

“…However, Leishmania tarentolae , a species of the subgenus Sauroleishmania , has a sympatric occurrence with L. infantum (Akhoundi et al., 2016; Klatt et al., 2019). In particular, L. tarentolae was isolated from the blood of Tarentola mauritanica geckoes collected near the city of Monopoli, Apulia (Pozio et al., 1986), a highly endemic region for canine leishmaniosis (CanL) in Italy (Mendoza‐Roldan et al., 2020b). This species was also isolated from Mediodactylus kotschyi (Pozio et al., 1983) in Italy and Tarentola annularis in Sudan (Elwasila, 1988).…”

Leishmania (Sauroleishmania) tarentolae isolation and sympatric occurrence with Leishmania (Leishmania) infantum in geckoes, dogs and sand flies

“…Geckoes, lizards, and sand flies were collected from May to November 2021 in two locations endemic for CanL, near Valenzano municipality (with 4.2 km of distance between each other), Apulia region, Italy [ 9 ]. These locations were Campus of Veterinary Medicine, University of Bari “Aldo Moro” (site 1; 41°1’31.584"N, 16°54’3.6288"E) and a private owned dog shelter (site 2; 41°03’04.3"N, 16°53’39.7"E), where dog blood samples were also collected and screened ( Fig 2 ).…”

“…Indeed, ecological and anthropic drivers (i.e., climate changes, animal translocation, wildlife movements, or globalization) have amplified the risk of alien Leishmania spp. introduction [ 8 ], and the spreading of sand fly populations in new localities results in the northward shift of leishmaniasis [ 9 ].…”