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Presently, 45% of the total human population of Europe, as well as their domestic and companion animals, are exposed to the risk of vector-borne helminths (VBH) causing diseases. A plethora of intrinsic biological and extrinsic factors affect the relationship among helminths, vectors and animal hosts, in a constantly changing environment. Although canine dirofilarioses by Dirofilaria immitis and Dirofilaria repens are key examples of the success of VBH spreading into non-endemic areas, another example is represented by Thelazia callipaeda eyeworm, an emergent pathogen of dogs, cats and humans in several regions of Europe. The recent finding of Onchocerca lupi causing canine and human infestation in Europe and overseas renders the picture of VBH even more complicated. Similarly, tick-transmitted filarioids of the genus Cercopithifilaria infesting the skin of dogs were recently shown to be widespread in Europe. Although for most of the VBH above there is an increasing accumulation of research data on their distribution at national level, the overall impact of the diseases they cause in dogs and humans is not fully recognised in many aspects. This review investigates the reasons underlying the increasing trend in distribution of VBH in Europe and discusses the diagnostic and control strategies currently available. In addition, this article provides the authors’ opinion on some topics related to VBH that would deserve further scientific investigation.

BackgroundThis study was aimed at investigating the distribution of a Cercopithifilaria sp. sensu Otranto et al., 2011 with dermal microfilariae recently identified in a dog from Sicily (Italy). A large epidemiological survey was conducted by examining skin samples (n = 917) and ticks (n = 890) collected from dogs at different time points in Italy, central Spain and eastern Greece.ResultsThe overall prevalence of Cercopithifilaria sp. in the sampled animal populations was 13.9% and 10.5% by microscopy of skin sediments and by PCR on skin samples, respectively. Up to 21.6% and 45.5% of dogs in Spain were positive by microscopical examination and by PCR. Cumulative incidence rates ranging from 7.7% to 13.9% were estimated in dogs from two sites in Italy. A low level of agreement between the two diagnostic tests (microscopical examination and PCR) was recorded in sites where samples were processed in parallel. Infestation rate as determined by tick dissection (from 5.2% to 16.7%) was higher than that detected by PCR (from 0% to 3.9%); tick infestation was significantly associated with Cercopithifilaria sp. infestation in dogs from two out of four sites. Developing larvae found in ticks were morphometrically studied and as many as 1469 larvae were found in a single tick.ConclusionsOur data suggest that, in addition to the most common species of filarioids known to infest dogs (i.e., Dirofilaria immitis, Dirofilaria repens and Acanthocheilonema reconditum), Cercopithifilaria sp. with dermal microfilariae should be considered due to its widespread distribution in southern Europe and high frequency in tick-exposed dogs.

Dirofilaria repens is a nematode affecting domestic and wild canids, transmitted by several species of mosquitoes. It usually causes a non-pathogenic subcutaneous infection in dogs and is the principal agent of human dirofilariosis in the Old World. In the last decades, D. repens has increased in prevalence in areas where it has already been reported and its distribution range has expanded into new areas of Europe, representing a paradigmatic example of an emergent pathogen. Despite its emergence and zoonotic impact, D. repens has received less attention by scientists compared to Dirofilaria immitis. In this review we report the recent advances of D. repens infection in dogs and humans, and transmission by vectors, and discuss possible factors that influence the spread and increase of this zoonotic parasite in Europe. There is evidence that D. repens has spread faster than D. immitis from the endemic areas of southern Europe to northern Europe. Climate change affecting mosquito vectors and the facilitation of pet travel seem to have contributed to this expansion; however, in the authors’ opinion, the major factor is likely the rate of undiagnosed dogs continuing to perpetuate the life-cycle of D. repens. Many infected dogs remain undetected due to the subclinical nature of the disease, the lack of rapid and reliable diagnostic tools and the poor knowledge and still low awareness of D. repens in non-endemic areas. Improved diagnostic tools are warranted to bring D. repens diagnosis to the state of D. immitis diagnosis, as well as improved screening of imported dogs and promotion of preventative measures among veterinarians and dog owners. For vector-borne diseases involving pets, veterinarians play a significant role in prevention and should be more aware of their responsibility in reducing the impact of the zoonotic agents. In addition, they should enhance multisectorial collaboration with medical entomologists and the public health experts, under the concept and the actions of One Health-One Medicine.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-3205-x) contains supplementary material, which is available to authorized users.

Canine vector-borne diseases (CVBDs) comprise a group of globally distributed and rapidly spreading illnesses that are caused by a range of pathogens transmitted by arthropods including ticks, fleas, mosquitoes and phlebotomine sandflies. In addition to their veterinary importance, some CVBD-causing pathogens are of major zoonotic concern. Recent studies using sophisticated and advanced methodologies and technologies have provided new insights into the epidemiology of many CVBDs. This review is the first of two articles and focuses on the zoonotic relevance of CVBDs, the significance of co-infection and the role of infected but clinically healthy dogs in spreading different pathogens among human and canine populations.

BackgroundThe taxonomic status of the brown dog tick (Rhipicephalus sanguineus sensu stricto), which has long been regarded as the most widespread tick worldwide and a vector of many pathogens to dogs and humans, is currently under dispute.MethodsWe conducted a comprehensive morphological and genetic study of 278 representative specimens, which belonged to different species (i.e., Rhipicephalus bursa, R. guilhoni, R. microplus, R. muhsamae, R. pusillus, R. sanguineus sensu lato, and R. turanicus) collected from Europe, Asia, Americas, and Oceania. After detailed morphological examination, ticks were molecularly processed for the analysis of partial mitochondrial (16S rDNA, 12S rDNA, and cox1) gene sequences.ResultsIn addition to R. sanguineus s.l. and R. turanicus, three different operational taxonomic units (namely, R. sp. I, R. sp. II, and R. sp. III) were found on dogs. These operational taxonomical units were morphologically and genetically different from R. sanguineus s.l. and R. turanicus. Ticks identified as R. sanguineus s.l., which corresponds to the so-called “tropical species” (=northern lineage), were found in all continents and genetically it represents a sister group of R. guilhoni. R. turanicus was found on a wide range of hosts in Italy and also on dogs in Greece.ConclusionsThe tropical species and the temperate species (=southern lineage) are paraphyletic groups. The occurrence of R. turanicus in the Mediterranean region is confirmed. A consensual re-description of R. sanguineus s.s. and R. turanicus will be necessary to solve the taxonomic problems within the so-called R. sanguineus group.

With the exception of Aelurostrongylus abstrusus, feline lungworms have been poorly studied. Information on their distribution is patchy and mostly limited to case reports. In this study, the occurrence of feline lungworms and co-infecting gastrointestinal parasites has been investigated in 12 European countries (i.e. Austria, Belgium, Bulgaria, France, Greece, Hungary, Italy, Portugal, Romania, Spain, Switzerland and the United Kingdom). An average of 10 domestic cats, with regular outdoor access, was sampled each month for 12months, and freshly passed faeces were collected. Stools were processed using a McMaster assay and a quantitative Baermann-Wetzel method. Animals positive for lungworms and/or gastrointestinal parasites were treated with a formulation containing fipronil, (S)-methoprene, eprinomectin, and praziquantel (Broadline®, Merial), and re-sampled 28days post-treatment. The association between lungworm infection and risk factors was analysed using statistical medians/means and the efficacy of the treatment against each lungworm species was assessed. Of 1990 cats sampled, 613 (30.8%) were positive for at least one parasite, while 210 (10.6%) were infected by lungworms. The prevalence of lungworm infection varied between the sampled sites, with the highest recorded in Bulgaria (35.8%) and the lowest in Switzerland (0.8%). None of the cats from Austria or the United Kingdom were infected by lungworms. Aelurostrongylus abstrusus was the species most frequently detected (78.1%), followed by Troglostrongylus brevior (19.5%), Eucoleus aerophilus (14.8%) and Oslerus rostratus (3.8%). The overall efficacy of the treatment was 99% for A. abstrusus and 100% for T. brevior, O. rostratus and E. aerophilus. Data presented provide a comprehensive account of the diagnosis, epidemiology and treatment of feline lungworms in Europe, as well as of the occurrence of co-infections by gastrointestinal parasites.

BackgroundDomestic cats can be infested by a large range of parasite species. Parasitic infestations may cause very different clinical signs. Endoparasites and ectoparasites are rarely explored in the same study and therefore multiparasitism is poorly documented. The present survey aimed to improve knowledge of the prevalence and risk factors associated with ecto- and endoparasite infestations in owned cats in Europe.MethodsFrom March 2012 to May 2013, 1519 owned cats were included in a multicenter study conducted in 9 veterinary faculties throughout Europe (Austria, Belgium, France, Hungary, Italy, Romania and Spain). For each cat, ectoparasites were checked by combing of the coat surface associated with otoscopic evaluation and microscopy on cerumen samples. Endoparasites were identified by standard coproscopical examinations performed on fresh faecal samples. Risk factors and their influence on parasitism were evaluated by univariate analysis followed by a multivariate statistical analysis (including center of examination, age, outdoor access, multipet status, and frequency of treatments as main criteria) with logistic regression models.ResultsOverall, 50.7% of cats resulted positive for at least one internal or one external parasite species. Ectoparasites were found in 29.6% of cats (CI95 27.3-32.0%). Otodectes cynotis was the most frequently identified species (17.4%), followed by fleas (15.5%). Endoparasites were identified in 35.1% of the cats (CI95 32.7-35.7%), including gastro-intestinal helminths in 25.7% (CI95 23.5-28.0), respiratory nematodes in 5.5% (CI95 4.2-7.0%) and protozoans in 13.5% (CI95 11.8-15.3%). Toxocara cati was the most commonly diagnosed endoparasite (19.7%, CI95 17.8-21.8%). Co-infestation with endoparasites and ectoparasites was found in 14.0% of the cats, and 11.9% harbored both ectoparasites and gastro-intestinal helminths.Age, outdoor access, living with other pets, and anthelmintic or insecticide treatments were significantly associated with the prevalence of various parasites.ConclusionsThis survey demonstrates that parasitism is not a rare event in European owned cat populations. The prevalence of multi-parasitism is significantly greater than expected by chance and hence there is tendency for some individual cats to be more prone to infestation by both endo- and ectoparasites due to common risk factors.