Incidence of Dirofilaria immitis and Leishmania infantum infections in sheltered dogs from Southern Italy

Leishmania infantum and Dirofilaria immitis are among the most important vector-borne pathogens in Europe, affecting animal and human health. In endemic areas, the epidemiology of both infections is conditioned by abundance of vectors and chemoprophylaxis measures. However, knowledge on the incidence of heartworm (HW) and Leishmania infections occurring in sympatry is still scant. Thus, this study aimed to evaluate the incidence of both infections in two dog shelters from southern Italy, which represent hotspots for these two diseases. In June and in October 2020, all dogs that previously scored negative for L. infantum (n = 111, site 1; n = 70, site 2) and D. immitis (n = 58, site 1; n = 61, site 2) in 2019 were tested for the estimation of the incidence of both infections. Anti-L. infantum IgG was detected by immunofluorescence antibody test, whereas D. immitis infection was diagnosed by modified Knott's test, SNAP 4Dx Plus test and real-time PCR. The overall D. immitis and L. infantum infection incidence values were both higher in site 2 (i.e. 63.9% and 10%, respectively) than site 1 (i.e. 39.7% and 1.8%, respectively). The dog shelter in site 2 was shown to be more suitable for the development of the mosquito/sand fly populations and, consequently, for the spreading of both parasites representing a potential threat for animal and human health. The high incidence of both infections recorded in this study suggests the need for chemoprophylaxis measures and vector monitoring and control to minimize the risk for animals and humans living in shelters or in their neighbourhoods.