Nodular lesions due to infestation by Dirofilaria repens in dogs from Italy

Abstract

Background Canine subcutaneous dirofilariosis caused by Dirofilaria repens is an important cause of human dirofilariosis in the Old World. Objectives To describe the clinical and pathological features of infestation by D. repens in dogs with cutaneous nodules and to discuss key diagnostic procedures. Animals Sixteen privately owned dogs of different breeds, ages and genders with subcutaneous nodules were positive for D. repens on at least one diagnostic test. Methods Diagnostic tests included cytological examination of fine‐needle aspiration biopsies, detection of circulating larvae by Knott's test, morphological and molecular identification of adult parasites and microfilariae, and histopathological examination of excised nodules. Results Twelve animals were positive for D. repens microfilariae, using cytology and at least one other diagnostic test. Four of twelve dogs screened by Knott's test had circulating D. repens microfilariae, and three of them were co‐infected with Dirofilaria immitis. In eight dogs, adult nematodes were morphologically identified as D. repens. Nodular panniculitis was observed in all cases, with nodules containing either one or several cross‐sections of nematodes and microfilariae. The nematodes extracted were identified as D. repens by an RT‐PCR on the second internal transcribed spacer (ITS‐2). Conclusions and clinical importance Adults and larvae of D. repens can induce skin nodules in dogs, and these lesions should be carefully evaluated in endemic areas. Clinicians should be aware that correct tissue sampling (including the storage of part of a sample in ethanol instead of formalin) is pivotal to achievement of a specific diagnosis. Cytology of fine‐needle tissue aspirates was shown to be useful.

Dirofilaria repens infection in a dog imported to Norway

“…Recently, Albanese et al [19] described the clinical and histopathological features of D. repen s infections in 16 dogs in Italy presenting with cutaneous nodules. In each case one to six nodules, measuring from 0.5 to 4 cm and located in different anatomical sites, were reported.…”

Filarioid infections in wild carnivores: a multispecies survey in Romania

“…In Europe, eight species of filarioids of four genera ( Dirofilaria : 2 species; Acanthocheilonema : 2 species; Cercopithifilaria : 3 species; and Onchocerca lupi ) have been reported in domestic dogs. Among these, most of the research has been focused on the zoonotic species, namely D. immitis , which causes a severe and life-threatening cardio-pulmonary disease in dogs [2], D. repens , which resides in the subcutaneous tissues of the canine host and is associated with a variety of dermatological conditions [3, 4] and, more recently, O. lupi , which is localized in the connective tissue of the sclera or in the retrobulbar regions of the eye of dogs [5]. Acanthocheilonema spp.…”

Human Dirofilaria repens infection of the zygomatico-temporal region

“…The microfilariae are taken up by various mosquito species that serve as intermediate hosts and transmit the disease to final or aberrant hosts (Genchi et al, 2011). The classical hosts of D. repens and D. immitis are dogs, but the reservoir for dirofilariae has extended to other carnivores such as cats, wolves, bears and foxes (Genchi et al, 2011, Pampiglione and Rivasi, 2000, Simón et al, 2012, Albanese et al, 2013. Furthermore, other species of the dirofilariae can eventually infect humans.…”

“…Dirofilariasis is caused by the canine filarial nematodes Dirofilaria (D.) repens and D. immitis (Genchi et al, 2011, Pampiglione and Rivasi 2000, Simón et al, 2012. Dirofilariae constitute a group of filarial nematodes infecting a number of carnivores as definitive hosts (Albanese et al, 2013). Adult dirofilariae are able to release microfilaria into the host's blood.…”