Evidences of increasing risk of dirofilarioses in southern Italy

Abstract

Given the spread of Aedes albopictus from northern to southern Italy, and the lack of updated data on Dirofilaria infections, this study was carried out to assess the infection risk for dogs and cats in Apulia region. During a 2-year study, 175 A. albopictus female specimens and samples of blood from 427 dogs (309 privately owned dogs and 118 shelter dogs) and 12 cats were collected. All blood samples were subjected to a modified Knott method, to a test for the detection of circulating Dirofilaria immitis antigen, and to a Dirofilaria species-specific real-time PCR for the simultaneous detection of D. immitis and Dirofilaria repens, targeting on partial cytochrome oxidase subunit 1 and internal transcribed spacer-2, respectively. Two abdomen and one thorax pools from A. albopictus were positive for D. immitis, with minimum infection rates of 1.14 and 0.51, respectively, and a probability of a single positive specimen to be infected of P = 0.6% (95% confidence interval (CI) = 0.12-1.73). Out of 439 examined subjects, 22 (5.0%) tested positive for Dirofilaria spp. in at least one diagnostic test. A specific D. immitis infestation rate of 3.5% was found among the privately owned dogs, while shelter dogs tested positive only for D. repens with a prevalence of 3.4%; one cat tested molecularly positive for D. immitis. There was a significantly higher rate of positivity among guard dogs for D. immitis (odds ratio, 6.24, 95% CI, 1.26-25.28; P < 0.05). The increasing risk of D. immitis infection in southern Italy is supported by the noteworthy positivity of A. albopictus populations and the cat. Our data highlight the usefulness to include filarioid infestation in routine diagnosis.