Angiostrongylus vasorum in foxes (Vulpes vulpes) and wolves (Canis lupus italicus) from Abruzzo region, Italy

Abstract

In Europe wildlife animals such as the red fox (Vulpes vulpes) are considered the main reservoir for Angiostrongylus vasorum as well as a potential threat for domestic dog infection. Though this parasite is endemic in fox populations, data on A. vasorum infection in wolves (Canis lupus italicus) are still scant, having only recently been described in Northwestern Spain, in Italy, in Croatia and in Slovakia. Based on the rising number of cases of canine lungworm infection in Central Italy (Abruzzo region), the aim of the present study was to investigate the infection by A. vasorum in fox and wolf populations sharing the same geographical area of dogs. From October 2008 to November 2019, A. vasorum specimens were collected, through routine post-mortem examination, from 56 carcasses (44 foxes and 12 wolves). Adult parasites were searched for in the right side of the heart and in pulmonary artery of all carcasses. First stage of larvae (L1) was searched in faeces using the Baermann technique and in lungs by tissue impressions. Overall, 230 adult specimens were collected and identified on a morphological basis. To confirm the morphological identification, 4 adult specimens (n = 3 from fox, n = 1 from wolf) were molecularly identified as A. vasorum by amplification of partial fragment of nuclear 18S rRNA (~1700 bp) genes. The anatomo-pathological and parasitological examinations indicated the presence of A. vasorum in 33 foxes (75%) and in 8 wolves (66.7%). The level of prevalence of infested wolves was higher than the previous one reported in other European countries. Interestingly, the prevalence of infection in foxes herein recorded was higher than that described in dogs (8.9%) living in the same geographical area. This result may confirm the hypothesis that the spread of canine angiostrongylosis is linked to fox populations infection.

Keywords: Abruzzo region; Angiostrongylus vasorum; Fox; Italy; Wolf.

Graphical abstract

Fig. 1

Map of the geographical areas of Europe where the presence of Angiostrongylus vasorum was reported before and after 2000 in definitive and intermediate hosts. This map was created by placing the reports of the literature in Eurostat's nomenclature units for statistics (NUTS).

Fig. 2

Province of Chieti, showing the municipalities of origin in which tested foxes resulted positive for Angiostrongylus vasorum.

Fig. 3

Province of Chieti, showing the municipalities of origin in which tested wolves resulted positive for Angiostrongylus vasorum.

Fig. 4

Angiostrongylus vasorum: scanning electron micrographies (SEM). A higher magnification of A) anterior end of adult worm, enface view showing the oral orifice; B) anterior end of adult worm, lateral view; C) posterior end of adult male, enface view showing copulatory bursa and spicules; D) detail of posterior end of adult male at higher magnification; E) posterior end of adult male, showing lateral rays of copulatory bursa.

Fig. 5

Lungs of wolf infested with Angiostrongylus vasorum in mild severity involvement.

Fig. 6

Lung of red fox: adult nematode within a pulmonary artery (A). Lung of wolf: nematode larvae were observed in alveolar spaces causing a thickening of connective tissue and a fibrotic response (B). Two nematode larvae were visible in the mediastinal lymph node of a red fox (C). Lymphocytic and eosinophilic infiltrates were present in brain tissue of a red fox infected with A. vasorum (D). Hematoxylin and Eosin (H&E) stain. Final magnification: × 100 (A–B), ×200 (C), × 400 (D). Scale bar: 200 μm (A–B), 100 μm (C), 50 μm (D). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)