Distribution of Angiostrongylus vasorum and its gastropod intermediate hosts along the rural–urban gradient in two cities in the United Kingdom, using real time PCR

Abstract

BackgroundAngiostrongylus vasorum is a highly pathogenic metastrongylid nematode affecting dogs, which uses gastropod molluscs as intermediate hosts. The geographical distribution of the parasite appears to be heterogeneous or patchy and understanding of the factors underlying this heterogeneity is limited. In this study, we compared the species of gastropod present and the prevalence of A. vasorum along a rural–urban gradient in two cities in the south-west United Kingdom.MethodsThe study was conducted in Swansea in south Wales (a known endemic hotspot for A. vasorum) and Bristol in south-west England (where reported cases are rare). In each location, slugs were sampled from nine sites across three broad habitat types (urban, suburban and rural). A total of 180 slugs were collected in Swansea in autumn 2012 and 338 in Bristol in summer 2014. A 10 mg sample of foot tissue was tested for the presence of A. vasorum by amplification of the second internal transcribed spacer (ITS-2) using a previously validated real-time PCR assay.ResultsThere was a significant difference in the prevalence of A. vasorum in slugs between cities: 29.4 % in Swansea and 0.3 % in Bristol. In Swansea, prevalence was higher in suburban than in rural and urban areas. Comparing the sampled slug fauna, Arion rufus was found in greater numbers in Swansea than Bristol, and was commonly infected (prevalence 41 %). This, alongside the timing of slug collections in summer rather than autumn, could explain low infection prevalence in the Bristol sample. In the absence of Ar. rufus as a preferred host for A. vasorum, Ar. flagellus and Limacus maculatus appear to act as versatile hosts that are present in suburban and urban areas in Swansea (prevalence in Ar. flagellus 33 %; in L. maculatus 44 %) and in Bristol (prevalence in Ar. flagellus 0.9 %). These slug species might provide A. vasorum with an alternative vehicle to reach the final host, when the main host Ar. rufus is scarce or absent.ConclusionWe conclude that the composition of the slug fauna varies spatially, and that this could help explain patchiness in the prevalence of A. vasorum. A suburban peak was found in the prevalence of infection in intermediate hosts, perhaps explained by a higher density of competent intermediate and/or definitive hosts.

Lungworms in Germany 2002 – 2016: Is there an Increase in Occurrence and Geographical Spread?

“…Current epidemiological data obtained from dogs with suspected lungworm infection support the hypothesis of the geographical spread of A. vasorum and C. vulpis as well (Maksimov et al 2017). (Aziz et al 2016). Finally, the influence of climate change is currently under discussion (Morgan et al 2009), but further studies are needed to clarify its role and mechanisms in the spread of A. vasorum.…”

“…These studies investigated different subpopulations and used different methodologies (summary in Table 1). A lot of effort has gone into researching the epidemiology of Angiostrongylosis, in particular in the wildlife reservoir fox (Table 2) and other species including mustelids (Simpson et al 2016) and wolves , but also in the intermediate hosts snails and slugs (Aziz et al 2016, Di Cesare et al 2015. Crenosoma vulpis is less the focus of research, probably because the pathology of this parasite is less severe and usually not life-threating, and veterinarians pay less attention to crenosomosis.…”

Evaluation of the Persistent Preventive Efficacy of 2.5 % Moxidectin/10 % Imidacloprid Spot-on (Advocate®, Advantage® Multi) in Dogs Experimentally Infected with Angiostrongylus vasorum

“…Growing prevalence in dogs and wildlife has been reported for A. vasorum (Taylor et al 2015, Barutzki et al 2017. There is also evidence for a growing infection rate in snails (Aziz et al 2016). Nowadays, improved diagnostic techniques are available which are less labour-intensive and more sensitive than the classical Baermann migration-sedimentation technique in detecting L1 of A. vasorum in faeces (Schnyder et al 2011 In endemic areas, regular monthly treatment throughout the period of the dog's potential exposure to infected snails and slugs will protect the dog from infection.…”

Standardization of a multiplex real-time PCR test for the identification of Angiostrongylus cantonensis, A. costaricensis and A. vasorum

“…que identificara las tres especies estudiadas en una sola reacción. En dos estudios sobre la PCR, se utilizaron secuencias ITS-2 como blanco de amplificación y solamente se identificó A. vasorum (44,48).…”