Species diversity of dermal microfilariae of the genus Cercopithifilaria infesting dogs in the Mediterranean region

Filarial Nematodes in Dogs from the Northeast Region of Brazil

PURPOSE

Medical and veterinary filarial nematodes are transmitted by blood-feeding vectors. In dogs, these parasites are mainly represented by nematodes in which microfilariae dwell in the blood (Dirofilaria spp. and Acanthocheilonema spp.) or skin (Cercopithifilaria spp. and Onchocerca lupi). The aim of this study was to determine the prevalence of these filarial infections in dogs residing in a touristic, heavily populated location in the northeastern region of Brazil.

METHODS

Blood samples (n = 245) were assessed by a modified Knott test, followed by a qualitative ELISA test (SNAP® 4Dx® Plus, IDEXX Laboratory, Westbrook, Maine, USA) for the detection of antibodies against Anaplasma spp., Borrelia burgdorferi sensu lato, Ehrlichia spp. and antigens of Dirofilaria immitis. Skin samples (n = 71) were microscopically examined and molecularly assessed through a PCR targeting the 12 S rRNA gene.

RESULTS

Microfilariae and antigen of D. immitis were detected simultaneously in 15 (6.1%; 95% CI = 3.7-9.8) animals. Nine animals (3.6%; 95% CI = 1.9-6.8) were D. immitis antigen positive but microfilariae negative and nine other animals (3.6%; 95% CI = 1.9-6.8) were microfilariae positive but D. immitis antigen negative. D. immitis positive dogs were found in four different municipalities. No filarioids were detected in the skin after microscopical and molecular analyses.

CONCLUSION

Data from this study demonstrate that D. immitis is the main filarial nematode infecting dogs in coastal areas in northeastern Brazil. Based on the potential risk of infection in which animals are submitted, it is essential to perform tests to detect microfilariae and D. immitis antigen. Preventive measures must be adopted by using microfilaricidal compounds and anti-feeding insecticides to prevent canine infection.

Cercopithifilaria spp. of dogs: little known but prevalent filarioids beneath the skin

Filarioids of the genus Cercopithifilaria are little studied, yet widespread parasites, that are relatively unique in being one of the very few nematodes transmitted by hard ticks. These filarioids live in the subcutis while microfilariae are found in the dermis. Definitive hosts include domestic dogs as well as a wide range of vertebrates, such as ruminants, non-human primates, murids, marsupials, porcupines, viverrids, bears and lagomorphs. The genus Cercopithifilaria contains three taxa (i.e. C. bainae, C. grassii and a yet undescribed species, namely Cercopithifilaria sp. II) that are known to infect dogs worldwide, with their occurrence overlapping the distribution of the main tick vector, Rhipicephalus sanguineus sensu lato. In recent decades, more attention has focused on these filarioids since they have been associated with clinical signs of infection, such as dermatitis, chronic polyarthritis and cutaneous cysts, and possibly with facilitating infections caused by other tick-borne pathogens. Nevertheless, these parasites remain largely underdiagnosed in clinical practice due to the lack of awareness of veterinary practitioners and to major obstacles to their diagnosis. In this review, we have assessed currently available data on Cercopithifilaria spp. infecting dogs worldwide and discussed the biological, clinical and epidemiological aspects of these filarioids, with the overall aim to gain a better understanding of their potential role in skin diseases.

Cutaneous filarioid nematodes of dogs in the United States: Are they emerging, neglected, or underdiagnosed parasites?

Filarioid nematodes, which are vector-borne parasites of cosmopolitan distribution, of dogs are medically important. They are represented by species in which microfilariae were found to be circulating in the bloodstream (e.g., Dirofilaria sp., Acanthocheilonema sp., and Brugia sp.) or skin-dwelling (e.g., Cercopithifilaria sp. and Onchocerca sp.). Those species whose microfilariae are detected in blood have been extensively studied, especially Dirofilaria immitis, due to their clinical importance. In recent decades, there has been an increased interest by the scientific community in filarioid nematodes whose microfilariae are detected in the skin because of the zoonotic aspect of Onchocerca lupi. In the United States (US), although D. immitis has been considered the main filarioid infecting dogs, the intense animal movement and global canine filarioid diversity may indicate that the likely presence of cutaneous filarioid nematodes is more common than previously expected. Hence, a question remains: Are these canine filarioid nematodes emerging, neglected, or simply underdiagnosed in the US? In this review, we provide an overview of pertinent information that briefly summarizes the biology of the different canine filarioid nematode species, clinical signs associated with infections, and currently available diagnostic tools using molecular and microscopy-based methods and highlight knowledge gaps where research and surveillance efforts remain necessary. The data herein presented serve as an alert to the scientific community about the importance of filarioid nematodes infecting dogs other than D. immitis. Additionally, the zoonotic potential of several filarioid species reinforces the necessity of a proper diagnosis and the need for broader surveillance to understand their diversity and distribution, to highlight the potential introduction of certain species, and mitigate their establishment in the country and new animal and human cases.

Estimated specific antibody-based true sero-prevalences of canine filariosis in dogs in Central Europe and the UK

Dirofilariosis is a vector-borne disease mainly caused by Dirofilaria immitis and Dirofilaria repens. In contrast to the known endemicity of dirofilariosis in southern and south-eastern Europe, information on the distribution of D. repens in Central-Europe is fragmentary. We tested 8877 serum samples from dogs from Austria, Denmark, Germany, Italy, Lithuania, Poland, Switzerland and the UK using an ELISA detecting filarial-specific antibodies, hypothesising higher occurrence of D. repens. Based on two overlapping frequency distributions, presumed negative samples had a mean optical density (OD) value of 0.097, representing 97.45% of all samples. Presumed positive samples, representing 2.55% of all sera, had a mean OD value of 0.287. Test prevalence based on the calculated cut-off was 3.51% for all sera (4.36% for Austria, 1.94% for Denmark, 1.39% for Germany, 3.37% for Italy, 6.90% for Lithuania, 6.99% for Poland, 0.77% for Switzerland and 0.0% for the UK, respectively). The bimodal distribution, representing overlapping distributions of OD values from positive and negative dogs, enabled the assignment of a probability of true infection status to each dog. Mean probabilities of true infection status across groups, based on the postal codes of origin, allowed us to estimate and map true prevalences. For all countries, except the UK, the true prevalence was lower than the test prevalence. The large number of serum samples and the use of a non-gold standard analytical method allowed us to create a more realistic picture of the distribution of D. repens in Central Europe and the UK.

Dermal microfilariae of dogs, jackals and cats in different regions of Iran

Background

Due to the complexity of retrieving skin-dwelling microfilariae, filarioids of dogs presenting dermal microfilariae (e.g. Cercopithifilaria spp., Onchocerca lupi) are relatively unknown compared to Dirofilaria spp. and Acanthocheilonema spp. whose microfilariae circulate in the blood. Although Cercopithifilaria spp. and O. lupi filarioids are distributed worldwide, there is a paucity of information on their occurrence in Iran. The aim of this study was to investigate these filarioids in a large population of dogs from different regions of Iran.

Methods

From October 2018 to September 2020, skin biopsies were obtained from dogs housed in shelters (n = 557) and privately owned dogs (n = 26) in seven provinces of Iran (Hamedan, Kermanshah, Yazd, Mazandaran, Khuzestan, Lorestan, Esfahan), as well as from three road-killed jackals (Canis aureus) and three cats (Felis catus) in Hamedan province. The skin biopsies were first soaked in saline solution at room temperature overnight, and examined for dermal microfilariae under the microscope. Positive skin specimens and sediments were tested by PCR for a 304-bp region of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene and amplicons were sequenced.

Results

Microfilariae of Cercopithifilaria spp. were found in skin biopsies of 32 of the 583 (5.5%) dogs tested, with infection rates of up to 25% in Kermanshah. No microfilariae were recovered from skin biopsy samples collected from dogs in Khorramabad and Ahvaz, nor from the examined jackals and cats. None of the privately owned dogs were found to be infected. Morphologic and morphometric characteristics of the microfilariae were consistent with C. bainae. Eighteen skin samples were positive for the cox1 gene, of which 15 sequences showed a nucleotide identity of 100% and three of 93.4% with the reference sequence of C. bainae available in GenBank (haplotype I; GenBank accession number: JF461457).

Conclusions

The data from this study broadens current knowledge on the geographical distribution of C. bainae in dogs in Middle Eastern countries. Further studies on different wild canine species in the country (e.g. jackal, fox, wolf) could provide further information on the epidemiology of these filarioids. A particular focus should be put on zoonotic O. lupi given the reports of its presence in human patients from this country.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-05141-2.

Haematological and biochemical abnormalities in hunting dogs infected with Acanthocheilonema reconditum, associated risk factors, and a European overview

Acanthocheilonema reconditum is a filarial parasite transmitted by arthropods (fleas, lice, and ticks) that infect dogs. There is minimal published data available to date on potential haematological and biochemical changes associated with this parasitic infection. Study aims were (i) provide an overview of A. reconditum in Europe, (ii) define A. reconditum prevalence and risk factors in a specific dog population (hunting) from southern Italy, and (iii) assess the frequency of haemato-biochemical abnormalities associated with infection. Blood samples collected from 3020 dogs were tested by a modified Knott's technique to count and identify microfilariae. Eighty-four dogs were infected by A. reconditum (2.78%; 95% CI 2.19-3.37%). Microfilariae ranged from 1 to 212/ml. Based on clinical examination, all but six dogs with non-specific symptoms were healthy. Haematological abnormalities included leucocytosis (n = 15), with eosinophilia (n = 14) and monocytosis (n = 13). Serum biochemical abnormalities included increased total serum proteins (n = 19), albumins (n = 7), total globulins (n = 14), ALT (n = 1), and ALP (n = 1); one dog was hypoalbuminemic, and BUN was mildly increased in 2 dogs. Risk factors included the province origin (Napoli, OR=5.4, 95%CI: 2.1-14.0; Caserta, OR=5.1, 95%CI: 2.5-10.6), hunting wild mammals (OR=2.8, 95% 95%CI: 1.6-4.8), and ectoparasite infestation (OR=1.9, 95%CI: 1.1-3.1). There was a negative correlation between microfilaraemic load and decreased albumin level (-0.37; p=0.021). Our results showed that A. reconditum circulates within the hunting dog population of southern Italy, with seemingly low pathogenic potential.

Efficacy of a spot-on formulation containing moxidectin 2.5%/imidacloprid 10% for the treatment of Cercopithifilaria spp. and Onchocerca lupi microfilariae in naturally infected dogs from Portugal

BACKGROUND

Onchocerca lupi and Cercopithifilaria spp. are vector-borne filarioids of dogs, which harbour skin microfilariae (mfs), the former being of zoonotic concern. Proper treatment studies using compounds with microfilaricidal activity have not been performed. Therefore, this study aimed to assess the efficacy of a commercially available spot-on formulation containing moxidectin 2.5%/imidacloprid 10% for the treatment of O. lupi or Cercopithifilaria spp. skin-dwelling mfs in naturally infected dogs.

METHODS

Privately owned dogs (n = 393) from southern Portugal were sampled via skin biopsies to identify and count mfs in 20 µl of skin sediment. A total of 22 mfs-positive dogs were allocated to treatment group (n = 11; G1) or left untreated as a control (n = 11; G2). As a pilot investigation to test the treatment efficacy, five dogs assigned to G1 were treated four times at monthly intervals with moxidectin 2.5%/imidacloprid 10% spot-on formulation on SDs 0, 28 (± 2), 56 (± 2), and 84 (± 2). Based on the negative results for both O. lupi and/or Cercopithifilaria spp. mfs of dogs in the pilot study from SD28 onwards, the remaining six dogs in G1 were treated at SD0 and assessed only at SD28.

RESULTS

Of the 393 animals sampled, 78 (19.8%) scored positive for skin-dwelling mfs. At the pilot investigation, a mean number of 19.6 mfs for O. lupi was recorded among five infected dogs whereas no mfs were detected at SD28. At SD0, the mean number of Cercopithifilaria spp. larvae was 12.6 for G1 and 8.7 for G2. The mean number of mfs for G2 was 20.09.

CONCLUSIONS

Results herein obtained suggest that a single treatment with moxidectin 2.5%/imidacloprid 10% spot-on formulation is efficacious against skin-dwelling mfs in dogs. The microfilaricidal effect of moxidectin could also be useful in reducing the risk of O. lupi infection for humans.

Role of Zoo-Housed Animals in the Ecology of Ticks and Tick-Borne Pathogens-A Review

Ticks are ubiquitous ectoparasites, feeding on representatives of all classes of terrestrial vertebrates and transmitting numerous pathogens of high human and veterinary medical importance. Exotic animals kept in zoological gardens, ranches, wildlife parks or farms may play an important role in the ecology of ticks and tick-borne pathogens (TBPs), as they may serve as hosts for local tick species. Moreover, they can develop diseases of varying severity after being infected by TBPs, and theoretically, can thus serve as reservoirs, thereby further propagating TBPs in local ecosystems. The definite role of these animals in the tick-host-pathogen network remains poorly investigated. This review provides a summary of the information currently available regarding ticks and TBPs in connection to captive local and exotic wildlife, with an emphasis on zoo-housed species.

Molecular Approach for the Diagnosis of Blood and Skin Canine Filarioids

The zoonotic Onchocerca lupi and tick-transmitted filarioids of the genus Cercopithifilaria remain less well known due to the difficulties in accessing to skin samples as target tissues. Here, we proposed a molecular approach reliying on multiplex qPCR assays that allow the rapid identification of filarioids from canine blood, skin, and tick samples. This includes two newly developed duplex qPCR tests, the first one targeting filarial and C. grassii DNA (CanFil-C. grassii). and the second qPCR assay designed for the detection of Cercopithifilaria bainae and Cercopithifilaria sp. II DNAs (C. bainae-C.spII). The third one is a triplex TaqMan cox 1 assay targeting DNA of blood microfilariae (e.g., Dirofilaria immitis, Dirofilaria repens and Acanthocheilonema reconditum). The novel duplex qPCRs developed were validated in silico and by screening of known DNA collection. The qPCR assays were also used for screening the blood and tick samples of 72 dogs from Algeria. This allowed the identification of canine filariasis infection with 100% of specificity and 89.47% and 100% of sensitivity from naturally infected blood and tick samples, respectively. The prevalences of 26.39% for D. immitis and 5.56% for both D. repens and A. reconditum were reported in blood and tick samples. Cercopithifilaria DNAs were detected only in tick samples, with a prevalence of 4.17% and 5.56% for C. bainae and Cercopithifilaria sp. II, respectively. Co-infections were diagnosed in 6.94% and 13.89% of blood and tick samples, respectively. Whereas all samples were negative for C. grassii DNA. The use of engorged ticks instead of blood and skin samples could be an easier option for the surveillance of all canine filarioids herein investigated. The multiplex qPCR assays herein validated were shown to be useful in the detection of filarial co-infections by overcoming sequencing of positive samples.

Cercopithifilaria species in dogs and ticks from Greece

Filarioids of the genus Cercopithifilaria (Spirurida, Onchocercidae) are parasites of wild and domestic animals in tropical and subtropical regions being transmitted by ixodid ticks. Though this filarioid species have been studied in canine and tick populations in Europe, data on their species diversity and geographical distribution in Greece is scant. Thus, the aims of this study were to investigate the presence of Cercopithifilaria spp. in dogs and ticks across Greece and to assess the possible risk factors. A total of 500 skin biopsies were collected from dogs, while 508 ticks were collected from 180 infested animals and examined. Sediments from skin biopsies were microscopically screened for detection of dermal microfilaria (mfs). Skin samples (n = 115) and tick specimens (n = 153) were molecularly subjected by PCR. Overall, 70 samples (14%) scored positive for mfs. Specifically, 68 samples (13.6%) were positive for Cercopithifilaria bainae and two (0.4%) were co-infected with C. bainae and Cercopithifilaria sp. II. Molecular analyses revealed that all sequences obtained belong to C. bainae. Haplotype I was the most frequent (92.6%), followed by haplotype XVIII (3%) and haplotypes II and IX (1.5%). Three new haplotypes of C. bainae, named XIX, XX, and XXI, were also identified. Among the risk factors examined, habitat, dog use, body weight, tick infestation history, and the use of acaricides were associated with the presence of C. bainae. The estimated prevalence of Cercopithifilaria spp. demonstrates that these filarioids are common in dogs and ticks in Greece. Finally, the identification of 7 haplotypes for C. bainae confirms their genetic variability.

Overview on Dirofilaria immitis in the Americas, with notes on other filarial worms infecting dogs

Canine dirofilariosis in the Americas is primarily caused by Dirofilaria immitis, a mosquito-borne filarial worm infecting dogs, which may also infect and cause disease in other mammalian hosts, including humans. Morphological and molecular evidence gathered in the past decades suggest that other Dirofilaria spp. may infect dogs in the American continent, though the actual taxonomic identity of them still needs to be elucidated. In addition, filarial worms belonging to distinct genera have also been reported in dogs in this part of the world, including Acanthocheilonema reconditum, Cercopithifilaria bainae, and Onchocerca lupi. Among these, O. lupi is a species of major clinical significance, which has been reported not only in dogs, but also in cats and humans in North America. The present article provides a current overview on canine dirofilariosis in the Americas, with notes on other filarial worms infecting dogs. It also provides some insights into outstanding research questions that should be responded to fill some of the several knowledge gaps related to this group of parasites in this continent.

Vector-borne nematode diseases in pets and humans in the Mediterranean Basin: An update

Vector-borne diseases (VBDs) are among the leading causes of morbidity and mortality in humans and animals. The scale of VBDs is increasing worldwide, including in the Mediterranean Basin, a region exposed to climate changes. Indeed, weather conditions may influence the abundance and distribution of vectors. The vector-borne nematode diseases of dogs and cats, such as dirofilariosis, onchocercosis, thelaziosis, Cercopithifilaria, and Acanthocheilonema infections, are some of these vectorized diseases, several of which are zoonoses. They are all caused by parasitic nematodes transmitted by arthropods, including mosquitoes (Dirofilaria spp.), black flies (Onchocerca lupi), drosophilids (Thelazia callipaeda), ticks (Acanthocheilonema dracunculoides and Cercopithifilaria bainae), and fleas and lice (Acanthocheilonema reconditum). The control and prevention of these infections and diseases require a multidisciplinary approach based on strengthening collaboration between the different actors in the fields of health, research, sociology, economics, governments and citizens, to improve human, animal, and ecosystem health. This is the concept of "one health." The review aimed to provide a general update on the spatial and temporal distribution of vector-borne nematodes diseases affecting companion animals and humans, as well as the vectors involved in the Mediterranean area. Simultaneously, certain epidemiological parameters, diagnosis, treatment, and control of these diseases based on the "one health" concept will also be discussed.

Dermatitis caused by autochthonous Cercopithifilaria bainae from a dog in Florida, USA: clinical, histological and parasitological diagnosis and treatment

BACKGROUND

Cercopithifilaria bainae is a tick-vectored filarioid nematode associated with erythematous dermatitis in dogs. It has not been reported previously in the United States.

HYPOTHESIS/OBJECTIVE

To describe clinical, histological and parasitological diagnosis and treatment of C. bainae in a dog.

ANIMALS

An 11-month-old golden retriever/standard poodle mixed breed dog from Florida (USA).

METHODS AND MATERIALS

The dog had no travel history within or outside the United States, was presented with a one month history of annular erythematous plaques on the head and ulcers on the medial canthi. Lesions were unresponsive to antibiotic treatment.

RESULTS

Histopathological evaluation of skin biopsies revealed an eosinophilic to lymphohistiocytic perivascular dermatitis with multiple microgranulomas and rare 5-10 μm diameter microfilariae within microgranulomas. Microfilarial morphology was consistent with C. bainae. PCR and sequencing of 18S rRNA and mitochondrial cytochrome oxidase subunit I genes confirmed the nematodes as C. bainae. The dog was treated with a commercial spot-on containing imidacloprid and moxidectin, and clinical resolution occurred.

CONCLUSIONS AND CLINICAL IMPORTANCE

To the best of the authors' knowledge, this is the first report of C. bainae in a dog in the United States and the first description of dermatological lesions caused primarily by C. bainae.

Screening of Cercopithifilaria bainae and Hepatozoon canis in ticks collected from dogs of Northeastern Brazil

Rhipicephalus sanguineus sensu lato (s.l.) is one of the most widespread ixodid ticks and is a competent vector of several vector-borne pathogens of veterinary and medical concern. For instance, this tick species transmits nematodes of the genus Cercopithifilaria and protozoa of the genus Hepatozoon to carnivores, including dogs. Here we investigated the occurrence of Cercopithifilaria spp. and Hepatozoon spp. in a population of ticks collected from naturally infested dogs living in rural areas of Northeastern Brazil. From August 2016 to June 2017, 758 tick specimens (mean ticks per month = 68.9 ± 71.4) were sampled from 75 dogs (mean ticks per dog = 10.11 ± 5.2) and dissected under a stereomicroscope in order to visualize Cercopithifilaria spp. larvae and Hepatozoon spp. oocysts and sporocysts. R. sanguineus s.l. was the only species collected, peaking in September (n = 273) and decreasing in February 2017 (n = 39). Different larval stages of Cercopithifilaria bainae were identified in 7 out of 758 (0.93%) ticks. In addition, 4 specimens (0.53%) were positive for oocysts and free sporocysts of Hepatozoon canis. The identity of both species of parasites was molecularly confirmed. These results account for the predominance of R. sanguineus (s.l.) in domestic dogs from rural locations of the study area, as well as for the presence C. bainae and H. canis in these tick populations.

Detection of Cercopithifilaria bainae in western Romania

Cercopithifilaria species are tick-transmitted filarial parasites of mammals. In Europe, three Cercopithifilaria spp. are known to parasitize dogs, all occurring mainly in the Mediterranean countries. In Romania, Cercopithifilaria bainae has been reported in a single dog in eastern Romania but the occurrence in other parts of the country is not known. To further elucidate the geographic distribution of Cercopithifilaria spp. infection, 544 ticks were collected from dogs in several locations across Romania. The presence of Cercopithifilaria spp. was investigated with real-time PCR. A single Dermacentor reticulatus female tick was found to be infected with Cercopithifilaria bainae. The finding in the present study is geographically separated from the previous finding in Romania by 800 km, as well as by the Carpathian mountain range. Hence, C. bainae is more geographically widespread in Romania than previously recognized. However, the single detection does suggest that infection is rather uncommon in Romanian dogs. Nevertheless, further studies on Cercopithifilaria spp. distribution and prevalence are needed.

Cercopithifilaria bainae in Rhipicephalus sanguineus sensu lato ticks from dogs in Brazil

Rhipicephalus sanguineus sensu lato (s.l.) ticks act as intermediate host for a range of canine vector-borne pathogens, including nematodes ranked in the genus Cercopithifilaria. Though being the object of several studies in the last years, information on the distribution of these parasites is still lacking. In this study, the occurrence of Cercopithifilaria spp. was investigated in on-host population of R. sanguineus s.l. collected from naturally infested dogs. Ticks (n=1906, including one larva, 294 nymphs and 1611 adults) were sampled on domestic dogs (n=155) living in the municipality of Garanhuns (northeastern Brazil). Tick collections (n=36) were performed every 8 days, from October 2015 to June 2016. Filarioid larvae detected at tick dissection were morphologically and morphometrically identified at species level. At the end of the study, only R. sanguineus s.l. ticks were collected, with the highest number in January 2016 (n=254) and the lowest in June 2016 (n=26). Out of 1906 dissected ticks, 2.68% (51/1906) harboured Cercopithifilaria bainae larvae, whose identification was molecularly confirmed, with a nucleotide identity of 99% with C. bainae. Data here reported indicate that, in the study area, R. sanguineus s.l. is the predominant tick infesting domestic dogs. Accordingly, these animals are at a high risk of C. bainae infection.

Cercopithifilaria sp. II in Vulpes vulpes: new host affiliation for an enigmatic canine filarioid

Cercopithifilaria bainae and Cercopithifilaria grassii (Spirurida, Onchocercidae) are filarioids inhabiting the skin of dogs worldwide. The microfilariae of a third species namely, Cercopithifilaria sp. II sensu Otranto et al. 2013, have been morphologically and molecularly characterized but scientific knowledge of this parasite is minimal. The first case of infection of a red fox (Vulpes vulpes) with the filarioid Cercopithifilaria sp. II is herein described in Castro Marim, Portugal. Microfilariae from skin sediment of the fox's ear were morphological characterized, and the identification was confirmed molecularly in samples from skin sediment, skin samples, and from Rhipicephalus sanguineus group ticks collected from the animal (99% homology with Cercopithifilaria sp. II). Studies should evaluate if red foxes might play a role in the maintenance and distribution of Cercopithifilaria sp. II infection in dog populations.

Filarioids infecting dogs in northeastern Brazil

Species of filarial nematodes belonging to the genera Dirofilaria and Acanthocheilonema are recognised as common parasites of dogs throughout the world. Recently, other filarioids featured by the presence of dermal microfilariae (e.g., Onchocerca lupi and Cercopithifilaria spp.) have been recognised in Europe. In Brazil, reports of filarioids in dogs are limited to Dirofilaria immitis, Acanthocheilonema reconditum and Cercopithifilaria bainae. To investigate the distribution of filarial infections in dogs living in an endemic region from northeastern Brazil, blood and skin samples (n=104) were microscopically (modified Knott's test and skin snip sediment examination) and molecularly evaluated. Twenty-two dogs (21.15%) were positive at microscopic and/or molecular examination for at least one filarioid species, with 21 (20.19%) animals positive for blood microfilariae at molecular and/or at microscopic examination. Microfilariae of D. immitis were detected in 12 (11.54%) animals, with co-infection of D. immitis and A. reconditum observed in four (3.85%) individuals. One animal was positive for C. bainae at both microscopic and molecular examination. Analysis of sequence obtained in the present study showed significant alignment identity with that of C. bainae from Europe. Considering that in the area of study arthropod vectors (mosquitoes, fleas and ticks) are prevalent throughout the year, preventive measures should be disposed in order to avoid the animal infestation and pathogen infection.

Redescription of Cercopithifilaria rugosicauda (Böhm & Supperer, 1953) (Spirurida: Onchocercidae) of roe deer, with an emended diagnosis of the genus Cercopithifilaria and a genetic characterisation

Newly collected material of Cercopithifilaria rugosicauda from roe deer Capreolus capreolus was analysed and compared to descriptions of C. rugosicauda from Austria and Hungary. The present specimens were assigned to the genus Cercopithifilaria using both morphological and molecular analyses. Complementary morphological data on the males and microfilariae of C. rugosicauda were described. The main morphological characters of different species of Cercopithifilaria were outlined and an emended generic diagnosis proposed. A genetic characterisation based on the analyses of cox1 and 12S rDNA sequences was reported supporting that C. rugosicauda was included in the clade of the genus Cercopithifilaria distinctly from other congeneric species available. However, these molecular analyses did not solve the relationships between the species of Cercopithifilaria. These could be approached using morphological characters that might be representative of their evolutionary history. In addition, Wolbachia was not seen in C. rugosicauda, either by immunohistological or by molecular approaches.

Chronic polyarthritis associated to Cercopithifilaria bainae infection in a dog

Despite the widespread distribution of Cercopithifilaria bainae among canine and tick populations worldwide, this filarioid is currently considered of 'minor importance' in veterinary medicine, particularly when compared to related filarioids, such as Dirofilaria immitis and Dirofilaria repens. To date, only a single case of dermatological alterations possibly associated to infection by C. bainae had been reported in a dog. In the present study, we describe the first case of systemic alterations associated to C. bainae infection in a dog suffering from diffused chronic polyarthritis. The animal had a previous history of reluctance to move and stiff gait and displayed multiple joint pain during manipulation of limbs. No biochemical, haematological and X-ray alterations were detected; microfilariae were observed in the synovial fluids collected from the joints. In spite of the morphological and molecular identification of these microfilariae as C. bainae, the dog did not respond to multiple microfilaricidal treatments with milbemicyn oxyme. The potential role of C. bainae in the pathogenesis of this clinical condition is discussed. Given the potential pathogenicity of this parasite, improved knowledge of this little known tick-borne nematode is warranted in order to assist the development of novel and effective treatment strategies.

Diversity of Cercopithifilaria species in dogs from Portugal

Background

Filarioids belonging to the genus Cercopithifilaria (Spirurida: Onchocercidae) have been described in dogs in association with Rhipicephalus sanguineus group ticks, which act as their biological vectors. This study represents the first investigation on Cercopithifilaria spp. in dogs from Portugal.

Findings

Dogs (n = 102) from the Algarve region (south of Portugal) were sampled by skin snip collection and tissues were left to soak overnight in saline solution. Sediments were observed under a light microscope and the detected microfilariae identified according to their morphology. Twenty-four dogs (23.5%) were found infected with at least one species of Cercopithifilaria, namely C. bainae (9.8%), C. grassii (3.9%) and Cercopithifilaria sp. II sensu Otranto et al., 2013 (13.7%). Results were confirmed by molecular amplification of partial cytochrome c oxidase subunit I and 12S rRNA genes and sequence analysis. Co-infections with more than one Cercopithifilaria species were detected in 3.9% of the animals.

Conclusions

This is the first report of Cercopithifilaria spp. in dogs from Portugal. The estimated level of infection with C. bainae, C. grassii and Cercopithifilaria sp. II suggests that these filarioids are prevalent in the canine population of southern Portugal.

First report of Cercopithifilaria spp. in dogs from Eastern Europe with an overview of their geographic distribution in Europe

Dogs in Europe may be parasitized by a variety of species of filarioids. While some species have been studied for decades, others have been only recently reported, and their range of distribution is still unknown. The present study was aimed to investigate the occurrence of Cercopithifilaria spp., whose microfilariae reside in the dermis and are transmitted by Rhipicephalus sanguineus s.l. ticks, in a dog population from Romania and to present the current knowledge of their distribution in Europe. Sampling was performed in a rural locality from Danube Delta region of Romania, location chosen due to the presence of the only known vector for these species. Skin samples were collected from 39 dogs. The samples were tested for the presence of Cercopithifilaria spp. by PCR methods. One animal (2.56%) was positive, and the amplified sequence showed a 100% similarity to Cercopithifilaria bainae. This study reports C. bainae for the first time in Eastern Europe, extending the known range of the genus in Europe.

Cercopithifilaria rugosicauda (Spirurida, Onchocercidae) in a roe deer and ticks from southern Italy

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First report of Cercopithifilaria rugosicauda in a roe deer and ticks from Italy.

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This study provides new morphological data on this little known nematode.

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The genetic data provide for the first time information on mitochondrial genes of C. rugosicauda.

Cercopithifilaria rugosicauda (Spirurida, Onchocercidae) is a subcutaneous filarial nematode of the European roe deer (Capreolus capreolus) transmitted by Ixodes ricinus (Acari, Ixodidae). At the necropsy of a roe deer from the Parco Regionale di Gallipoli Cognato (Basilicata region, southern Italy), two female nematodes of C. rugosicauda were found. Following the necropsy, seven skin snips were sampled from different body regions and 96 I. ricinus ticks were collected. In addition, 240 ticks were collected by dragging in the enclosure where the roe deer lived. Samples were examined for the presence of C. rugosicauda larvae and assayed by PCR targeting cytochrome c oxidase subunit 1 (cox1, ∼300 bp) and 12S rDNA (∼330 bp) gene fragments. Female nematodes, microfilariae from skin samples and eight third stage larvae (L3) from ticks were morphologically and molecularly identified as C. rugosicauda. Phylogenetic analyses clustered this species with other sequences of Cercopithifilaria spp. This study represents the first report of C. rugosicauda in a roe deer and ticks from Italy and provides new morphological and molecular data on this little known nematode.

Incidence of Cercopithifilaria bainae in dogs and probability of co-infection with other tick-borne pathogens

Background

Cercopithifilaria bainae is a filarioid parasite that infects dogs, being transmitted by Rhipicephalus sanguineus group ticks in many countries of the Mediterranean basin. This study assessed the incidence density rate (IDR) of infection by C. bainae in dogs and the probability of co-infection with other tick-borne pathogens (i.e., Anaplasma platys, Babesia vogeli and Hepatozoon canis), in an area of high endemicity in southern Italy.

Methodology/Principal Findings

From March 2011 to October 2012, a field study involving 58 young dogs naturally exposed to tick infestation was conducted. Skin and blood samples obtained from each dog six times during an 18-month period were tested for C. bainae by parasite detection within skin snip sediments, with subsequent confirmation through PCR and DNA sequencing. Dogs examined monthly for ticks and A. platys, B. vogeli and H. canis were microscopically and/or molecularly diagnosed and after the first and the second summer seasons, the IDR for positive animal-month at risk was 3.8% and 1.7% in November 2011 and October 2012, respectively. All 58 C. bainae-infected dogs were simultaneously infected with at least one other tick-borne pathogen. After the first summer season (assessment in November 2011), a C. bainae-infected dog had a 33% probability of being infected with H. canis or A. platys, whereas after the second tick season (assessment in October 2012) the probability of co-infection was 78%, 22% and 11% for H. canis, A. platys and B. vogeli, respectively.

Conclusions

Our data indicate that tick-infested dogs are at risk of acquiring infection by C. bainae. In addition, the detection of C. bainae microfilariae indicates a prior tick exposure and, should stimulate testing for other tick-borne disease causing pathogens.

Cutaneous distribution and circadian rhythm of Onchocerca lupi microfilariae in dogs

BACKGROUND

Among the arthropod-borne nematodes infesting dogs, Onchocerca lupi (Spirurida: Onchocercidae) is of increasing zoonotic concern, with new human cases of infection diagnosed in Turkey, Tunisia, Iran and the USA. Knowledge of the biology of this nematode is meagre. This study aimed at assessing the distribution and periodicity of O. lupi microfilariae from different body regions in naturally infested dogs.

METHODOLOGY/PRINCIPAL FINDINGS

Skin samples were collected from six dogs infested with O. lupi but without apparent clinical signs. Two skin samples were collected from 18 anatomical regions of dog 1 at necropsy. In addition, single skin biopsies were performed from the forehead, inter-scapular and lumbar regions of dogs 2-6, in the morning, afternoon, and at night. Two aliquots of the sediment of each sample were microscopically observed, microfilariae counted and morphologically and molecularly identified. Most of the 1,667 microfilariae retrieved from dog 1 were in the right ear (59.6%), nose (26.5%), left ear (6.7%), forehead (3.0%), and inter-scapular (2.9%) regions. In dogs 2-6, the overall mean number of microfilariae was larger on the head (n = 122.8), followed by the inter-scapular (n = 119.0) and lumbar (n = 12.8) regions. The overall mean number of microfilariae was larger in the afternoon (153.4), followed by night (75.4) and morning (25.8).

CONCLUSIONS

Onchocerca lupi microfilariae were more common in the head (i.e., ears and nose) than in the remaining part of the dog's body, indicating they tend to aggregate in specific body regions, which are the best sites to collect skin samples for diagnostic purposes. The periodicity pattern of microfilariae of O. lupi and their concentration in specific body regions is most likely a result of the co-evolution with their as-yet-unknown vector. The detection of skin microfilariae in asymptomatic animals, suggests the potential role of these animals as carriers and reservoirs of O. lupi.

Cercopithifilaria spp. in dogs in Sardinia Island (Italy)

A survey on Cercopithifilaria spp. was carried out on owned and kennelled dogs in Sardinia, Italy. A total of 180 dogs were sampled and tested by microscopic detection or PCR of dermal microfilariae in skin snip sediments. The overall prevalence for Cercopithifilaria spp. at both microscopy and molecular tests was 9.4 % (17/180), while 8.3 % (15/180) of dogs scored positive at microscopic detection of sediments only. Of the 225 microfilariae measured, 212 were identified as Cercopithifilaria bainae and the remaining as Cercopithifilaria sp. II. All samples were molecularly processed for specific amplification of cytochrome oxidase subunit 1 (cox1) and ribosomal 12S gene fragments. The Basic Local Alignment Search Tool analysis of the cox1 and 12S sequences here obtained showed a high nucleotide similarity (99 and 100 %, respectively) with those of C. bainae available in GenBank. In particular, cox1 haplotype I (HI; n=14), haplotype HXVIII (n=2), and a new haplotype, named HXIX (n=1), differing for a single polymorphism from HI, were detected. This study reports data on the occurrence, distribution, and genetic makeup of C. bainae and Cercopithifilaria sp. II infesting dogs in Sardinia, suggesting that these filarioids are spread in areas where Rhipicephalus sanguineus sensu lato ticks occur.

Redescription of Cercopithifilaria bainae Almeida & Vicente, 1984 (Spirurida, Onchocercidae) from a dog in Sardinia, Italy

Background

Three species of the genus Cercopithifilaria have been morphologically and molecularly characterized in dog populations in southern Europe: Cercopithifilaria grassii (Noè, 1907), Cercopithifilaria sp. sensu Otranto et al., 2011 (reported as Cercopithifilaria sp. I), and Cercopithifilaria sp. II sensu Otranto et al., 2012. The adults of Cercopithifilaria sp. I have remained unknown until the present study.

Methods

The material originated from a dog from Sardinia (Italy) diagnosed with dermal microfilariae of Cercopithifilaria sp. I. The holotype and three paratypes of Cercopithifilaria bainae Almeida & Vicente, 1984, described from dogs in Brazil, were studied as comparative material. A cox1 (~689 bp) and 12S (~330 bp) gene fragments were amplified and phylogenetic analysis carried out.

Results

The highest numbers of adult nematodes (82%) were collected in the sediment of the subcutaneous tissues of the trunk (n = 37) and forelimbs (n = 36). The morphology of the adult nematodes and microfilariae collected from the dog in Sardinia corresponded to those of C. bainae. All cox1 and 12S gene sequences showed a high homology (99-100%) with sequences from microfilariae of Cercopithifilaria sp. I.

Conclusions

The morphological and molecular identity of the microfilariae of C. bainae overlap those described previously as Cercopithifilaria sp. sensu Otranto et al., 2011 (=Cercopithifilaria sp. I). Therefore, the present study reports the occurrence of C. bainae in Europe, for the first time after its description and the single record in Brazil. C. bainae appears to be highly diffused in dog populations in southern Europe. The phylogenetic analyses based on cox1 and 12S do not reveal the three species of Cercopithifilaria parasitizing dogs as a monophyletic group, which suggests that they have derived independently by host switching.

Infective larvae of Cercopithifilaria spp. (Nematoda: Onchocercidae) from hard ticks (Ixodidae) recovered from the Japanese serow (Bovidae)

Hard ticks taken from the Japanese serow, Capricornis crispus, in Yamagata Prefecture, Honshu, harboured infective larvae of onchocercid filariae after incubation from the 22nd to the 158th day. Haemaphysalis flava and H. japonica contained one to eight filarial larvae; females, males and a nymph of the ticks were infected. The 44 infective larvae recovered were 612-1,370 μm long, and 11 of them, 930-1,340 μm long, were studied in detail. The larvae possessed the morphologic characteristics of the larvae of the genus Cercopithifilaria, namely an oesophagus with a posterior glandular part, no buccal capsule and a long tail with three terminal lappets. Five types (A to E) of infective larvae were identified based on the morphologic characteristics. While to date five species of Cercopithifilaria have been described from the Japanese serow, a specific identification of the larvae found in this study was generally not possible. Only type E larvae could be tentatively assigned to Cercopithifilaria tumidicervicata, as they had a cervical swelling similar to that of the adults of this species. A key for the identification of the five larval types is presented. The study presents circumstantial evidences indicating that H. flava and H. japonica may transmit Cercopithifilaria spp. to Japanese serows. It also suggests the possibility that such filarial larvae will be found in hard ticks anywhere, because Cercopithifilaria is distributed worldwide, though this genus generally goes unnoticed, as its microfilariae occur in the skin, not in the blood, of host animals.

Vector-borne helminths of dogs and humans in Europe

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.