Angiostrongylus vasorum infection in dogs from a cardiopulmonary dirofilariosis endemic area of Northwestern Italy: a case study and a retrospective data analysis.

BACKGROUND: In Italy, Angiostrongylus vasorum, an emergent parasite, is being diagnosed in dogs from areas considered free of infection so far. As clinical signs are multiple and common to other diseases, its diagnosis can be challenging. In particular, in areas where angiostrongylosis and dirofilariosis overlap, a misleading diagnosis of cardiopulmonary dirofilariosis might occur even on the basis of possible misleading outcomes from diagnostic kits. CASE PRESENTATION: Two Cavalier King Charles spaniel dogs from an Italian breeding in the Northwest were referred to a private veterinary hospital with respiratory signs. A cardiopulmonary dirofilariosis was diagnosed and the dogs treated with ivermectin, but one of them died. At necropsy, pulmonary oedema, enlargement of tracheo-bronchial lymphnodes and of cardiac right side were detected. Within the right ventricle lumen, adults of A. vasorum were found. All dogs from the same kennel were subjected to faecal examination by FLOTAC and Baermann's techniques to detect A. vasorum first stage larvae; blood analysis by Knott's for Dirofilaria immitis microfilariae, and antigenic tests for both A. vasorum (Angio Detect™) and D.immitis (DiroCHEK® Heartworm, Witness®Dirofilaria). The surviving dog with respiratory signs resulted positive for A. vasorum both at serum antigens and larval detection. Its Witness® test was low positive similarly to other four dogs from the same kennel, but false positive results due to cross reactions with A. vasorum were also considered. No dogs were found infected by A. vasorum. Eventually, the investigation was deepened by browsing the pathological database of Veterinary Pathology Laboratories at Veterinary School of Milan University through 1998-2016, where 11 cases of angiostrongylosis were described. Two out of 11 dogs had a mixed infection with Crenosoma vulpis. CONCLUSION: The study demonstrates the need for accurate surveys to acquire proper epidemiological data on A. vasorum infection in Northwestern Italy and for appropriate diagnostic methods. Veterinary clinicians should be warned about the occurrence of this canine parasite and the connected risk of a misleading diagnosis, particularly in areas endemic for cardiopulmonary dirofilariosis.

Is Angiostrongylosis a Realistic Threat for Domestic Cats?

Three species of Angiostrongylus have been found in felids thus far, i.e., Angiostrongylus chabaudi, Angiostrongylus felineus and Angiostrongylus vasorum. Angiostrongylus chabaudi lives in the right heart and pulmonary arteries of the definitive natural host, the European wildcat (Felis silvestris), and non-patent infections have been reported in domestic cats (Felis catus). Angiostrongylus felineus, described in the Puma yaguarondi (Herpailurus yagouaroundi), has never been reported in domestic felids, while recently a non-patent infection by A. vasorum was unequivocally described in a F. catus. Nonetheless, epizootiological and clinical relevance of angiostrongylosis in domestic cats are practically unknown. This study investigated whether cases of angiostrongylosis may be missed in cats living in areas enzootic for Angiostrongylus spp. and other metastrongyloids. Overall, 100 cats that were either positive (n.50) or negative (n.50) for metastrongyloid larvae at the Baermann's test, were examined for Angiostrongylus spp. with DNA-based methods and with the serological test Angio Detect™ for circulating antigen. The PCR analysis confirmed the copromicroscopy results, where 25 cats scored positive for Aelurostrongylus abstrusus, 16 for Troglostrongylus brevior and 9 for both, while no cats were positive for Angiostrongylus-like larvae, including A. chabaudi. None of the 100 sera samples scored positive at the Angio Detect™ test. These data suggest that currently feline angiostrongylosis is a minor parasitosis for domestic cats. Nevertheless, it cannot be excluded that the epizootiological drivers which have favored the spillover of A. vasorum and T. brevior from wildlife to dogs and cats, could promote the emergence of feline angiostrongylosis, with an unpredictable health impact.

Use of a commercial serologic test for Angiostrongylus vasorum for the detection of A. chabaudi in wildcats and A. daskalovi in badgers.

Three species of the genus Angiostrongylus are known to infect European carnivores: A. vasorum (mainly in canids but also in other carnivores), A. chabaudi (in felids) and A. daskalovi (in mustelids). A. vasorum is responsible for clinically severe disease in domestic dogs, most commonly diagnosed based on fecal examination and serological detection of circulating antigens. Considering the poorly known host range and the challenging larval differentiation in the feces between the three species of Angiostrongylus infecting European carnivores, our aim was to evaluate the cross-reactivity of A. chabaudi and A. daskalovi with A. vasorum using a commercial serologic test developed for domestic dogs. Badgers (Meles meles) (n=10) and wildcats (Felis silvestris) (n=8) were examined between 2015 and 2016 by full parasitological necropsy with subsequent morphological and molecular identification of nematodes and by serology, using IDEXX Angio Detect™ tests. Five out of the ten badgers and two out of the eight wildcats were harboring nematodes in the pulmonary arteries. All nematodes were identified morphologically as A. daskalovi in badgers and A. chabaudi in wildcats, respectively. Serological examination of the plasma samples revealed the positivity of the same animals as found in necropsy. None of the animals negative at necropsy was positive at serology. The 100% correlation between the necropsy results and the serologic positivity to IDEXX Angio Detect™ in badgers infected with A. daskalovi and wildcats infected with A. chabaudi suggest that these rapid tests are able to identify circulating antigens of all species of Angiostrongylus found in European carnivores: A. vasorum, A. daskalovi and A. chabaudi. The possibility for future in-clinic use of this test in domestic cats should be further investigated.

Comparison of three methods for the detection of Angiostrongylus vasorum in the final host.

Angiostrongylosis is potentially fatal parasitic nematode infection affecting dogs which can be difficult to diagnose. In recent years several microscopical, serological and molecular detection methods have been developed, however there are few studies that have compared the relative performance of these methods. Screening necropsy material from an opportunistic sample of 140 foxes (82 of which were considered to be infected with Angiostrongylus vasorum), indicated sensitivities of 84.1% for dissection and visual examination of plucks, 69.5% for nested PCR of an 18S rRNA fragment and 76.8% for a canine A. vasorum antigen detection test (IDEXX Angio Detect) of tissue fluid samples respectively. Agreement between the tests ranged from 45.6 to 79.7%. A novel nested PCR-RFLP for the detection and identification of canid lungworm spp. is described.