Habitat Characteristics as Potential Drivers of the Angiostrongylus daskalovi Infection in European Badger (Meles meles) Populations

From 2016 to 2020, an investigation was carried out to identify the rate of Angiostrongylus spp. infections in European badgers in Hungary. During the study, the hearts and lungs of 50 animals were dissected in order to collect adult worms, the morphometrical characteristics of which were used for species identification. PCR amplification and an 18S rDNA-sequencing analysis were also carried out. Global and local spatial autocorrelation methods were used to detect high-rated and low-rated infected animal clusters. We conducted a binary logistic regression analysis along with hierarchical agglomerative clustering to determine the relation between selected biotic and abiotic variables, and the prevalence of an A. daskalovi infection. We found a high prevalence (72%) and moderate mean intensity (14.1) of Angiostrongylus sp. infection. Morphology and sequencing revealed that all animals were infected by A. daskalovi. The results of both spatial autocorrelations suggested that the spatial distribution of infected badgers was more spatially clustered than random. The results of an analysis of the correlation between habitat characteristics and infection showed that the infected animals could be associated with dry and open landscape habitats without extended and connected canopy. It is suggested that the territorial behaviour of badgers and the landscape-directed aggregation of potential intermediate hosts might be the drivers of an A. daskalovi infection.

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.

A rare cardiopulmonary parasite of the European badger, Meles meles: first description of the larvae, ultrastructure, pathological changes and molecular identification of Angiostrongylus daskalovi Janchev & Genov 1988

Background

Angiostrongylus daskalovi is a rare cardiopulmonary nematode infecting badgers. The parasite was described in 1988 and, since then, found only once in mustelids in Europe. The present study aims to report new cases of patent A. daskalovi infection in badgers from northern Romania and to provide new information on its ultrastructure, molecular diagnosis, and pathology.

Methods

Eight road-killed or hunted badgers originating from Maramureș and Alba counties in Romania were collected and necropsied. Adults and larvae of cardio-pulmonary nematodes were collected and examined by light and scanning electron microscopy (SEM). Genomic DNA was extracted from adults and first-stage larvae (L1). PCR amplification of the internal transcribed spacer 2 (ITS2, ∼500 bp) of the rRNA gene was performed. Amplicons were purified, sequenced, and compared to those available in the GenBank database. Histopathological examination of the lungs was performed and lesions described.

Results

The necropsy revealed the presence of nematodes in the pulmonary arteries of three animals. All parasites were mature adults and the coproscopic examination showed the presence of eggs and L1 larvae in all three positive animals. Light microscopy examination confirmed the morphological and morphometric similarity of parasites to Angiostrongylus daskalovi. SEM highlighted the typical angiostrongylid structure of the rays of the copulatory bursa and the anterior extremity, with the presence of six sensory papillae surrounding the mouth opening in which a triangular tooth was visible. The first-stage larva (L1) of A. daskalovi is described here for the first time. Histopathological examination of the lungs showed chronic interstitial verminous pneumonia due to the presence of adult parasites. Molecular analysis showed 100 % nucleotide similarity to an Angiostrongylus sp. isolate originating from a badger from Spain, tentatively identified as A. daskalovi.

Conclusions

Our study unequivocally demonstrates the presence of A. daskalovi in European badgers from Romania, provides the first description of the larvae and reveals new data about the ultrastructure of adult parasites and their pathological impact, contributing to the understanding of the phylogenetic relationships with other congeneric species.