A SYBR green real-time PCR assay for the detection of the nematode Angiostrongylus vasorum in definitive and intermediate hosts

A Taq-Man-based multiplex quantitative PCR for the simultaneous detection and quantification of Angiostrongylus vasorum, Crenosoma vulpis, and species of respiratory capillarids in canids

In recent years, Angiostrongylus vasorum, Crenosoma vulpis, Eucoleus aerophilus (syn. Capillaria aerophila) and Eucoleus boehmi (syn. Capillaria boehmi), commonly referred to as canine lungworms, have gained a growing interest worldwide as the result of their geographical expansion. Each of these nematode species differs considerably in its biology and pathogenicity. Despite their impact on dogs' health, these parasites are often underdiagnosed owing to diagnostic challenges. Here, we describe the development and validation of a Taq-Man-based multiplex quantitative PCR (qPCR) for the simultaneous detection of the main species of canine lungworms in faeces of infected dogs. Using 10-fold serial dilutions of synthetic gene block fragments containing individual sequence targets of each lungworm species, the analytical sensitivity of the assay ascertained was 1.84 ng/μl for A. vasorum, 3.08 ng/μl for C. vulpis and 0.79 ng/μl for Eucoleus spp. The sensitivity of the assays and their ability to detect mixed species infections were compared with microscopy-based techniques (faecal floatation and Baermann technique) applied to faecal samples submitted for lungworm testing through an accredited diagnostic laboratory at the Institute of Parasitology, University of Zurich, Switzerland, and from community dogs as part of a research project on canine endoparasites in Cambodia. The multiplex qPCR displayed high diagnostic sensitivity (42/46, 91.3%; 95% Confidence Interval (CI): 79.1-97.1%) and a diagnostic specificity of 100% (45/45, 95% CI: 90.6-100%), and was able to detect 42.9% additional mixed lungworm species infections compared with microscopy-based methods. Kappa statistics showed substantial agreement between the qPCRs and microscopy for mixed infections (κ = 0.72, 95% CI: 0.4-1) and Eucoleus spp. (κ = 0.65, 95% CI: 0.45-0.85) and almost perfect agreement for C. vulpis (κ = 0.85, 95% CI: 0.63-1) and A. vasorum (κ = 0.92, 95% CI: 0.84-1). This multiplex qPCR enables timely, accurate, and sensitive diagnosis of canine lungworm species in faecal samples and can be used to monitor the geographical distribution and emergence of these parasitic species, globally.

Gut microbiota in parasite-transmitting gastropods

BACKGROUND

Gastropoda, the largest class within the phylum Mollusca, houses diverse gut microbiota, and some gastropods serve as intermediate hosts for parasites. Studies have revealed that gut bacteria in gastropods are associated with various biological aspects, such as growth, immunity and host-parasite interactions. Here, we summarize our current knowledge of gastropod gut microbiomes and highlight future research priorities and perspectives.

METHODS

A literature search was undertaken using PubMed, Web of Science and CNKI for the articles on the gut microbiota of gastropods until December 31, 2022. We retrieved a total of 166 articles and identified 73 eligible articles for inclusion in this review based on the inclusion and exclusion criteria.

RESULTS

Our analysis encompassed freshwater, seawater and land snails, with a specific focus on parasite-transmitting gastropods. We found that most studies on gastropod gut microbiota have primarily utilized 16S rRNA gene sequencing to analyze microbial composition, rather than employing metagenomic, metatranscriptomic, or metabolomic approaches. This comprehensive review provided an overview of the parasites carried by snail species in the context of gut microbiota studies. We presented the gut microbial trends, a comprehensive summary of the diversity and composition, influencing factors, and potential functions of gastropod gut microbiota. Additionally, we discussed the potential applications, research gaps and future perspectives of gut microbiomes in parasite-transmitting gastropods. Furthermore, several strategies for enhancing our comprehension of gut microbiomes in snails were also discussed.

CONCLUSIONS

This review comprehensively summarizes the current knowledge on the composition, potential function, influencing factors, potential applications, limitations, and challenges of gut microbiomes in gastropods, with a specific emphasis on parasite-transmitting gastropods. These findings provide important insights for future studies aiming to understand the potential role of gastropod gut microbiota in controlling snail populations and snail-borne diseases.

Comparative biology of parasitic nematodes in the genus Angiostrongylus and related genera

The rise to prominence of some Angiostrongylus species through associated emerging disease in humans and dogs has stimulated calls for a renewed focus on the biology of this genus and three related genera. Although significant research efforts have been made in recent years these have tended to focus on individual species and specific aspects such as diagnosis and treatment of disease or new records of occurrence and hosts. This comprehensive review takes a comparative approach, seeking commonalities and differences among species and asking such questions as: Which species belong to this and to closely related genera and how are they related? Why do only some species appear to be spreading geographically and what factors might underlie range expansion? Which animal species are involved in the life cycles as definitive, intermediate, paratenic and accidental hosts? How do parasite larvae find, infect and develop within these hosts? What are the consequences of infection for host health? How will climate change affect future spread and global health? Appreciating how species resemble and differ from each other shines a spotlight on knowledge gaps and provides provisional guidance on key species characteristics warranting detailed study. Similarities exist among species, including the basic life cycle and transmission processes, but important details such as host range, climatic requirements, migration patterns within hosts and disease mechanisms differ, with much more information available for A. cantonensis and A. vasorum than for other species. Nonetheless, comparison across Angiostrongylus reveals some common patterns. Historically narrow definitive host ranges are expanding with new knowledge, combining with very broad ranges of intermediate gastropod hosts and vertebrate and invertebrate paratenic and accidental hosts to provide the backdrop to complex interactions among climate, ecology and transmission that remain only partly understood, even for the species of dominant concern. Key outstanding questions concern larval dynamics and the potential for transmission outside trophic relations, relations between infection and disease severity in different hosts, and how global change is altering transmission beyond immediate impacts on development rate in gastropods. The concept of encounter and compatibility filters could help to explain differences in the relative importance of different gastropod species as intermediate hosts and determine the importance of host community composition and related environmental factors to transmission and range. Across the group, it remains unclear what, physiologically, immunologically or taxonomically, delimits definitive, accidental and paratenic hosts. Impacts of infection on definitive host fitness and consequences for population dynamics and transmission remain mostly unexplored across the genus. Continual updating and cross-referencing across species of Angiostrongylus and related genera is important to synthesise rapid advances in understanding of key traits and behaviours, especially in important Angiostrongylus species that are emerging causative agents of disease in humans and other animals.

Angiostrongylus vasorum in Estonia: Multi-center study in dogs with clinical signs suggestive of canine angiostrongylosis, survey of potential risk behaviors among the dogs, and questionnaire survey of knowledge about the parasite among veterinarians

Angiostrongylus vasorum is a parasite that can cause life-threatening disease in dogs. In recent years, A. vasorum has been reported spreading into new areas, in particular towards northeastern Europe. Despite being detected in wildlife in Estonia, no studies have focused on A. vasorum in domestic dogs in the country. We conducted a multi-center study in 2018-2019: at eight small animal clinics, altogether 115 dogs that had clinical signs that could be suggestive of canine angiostrongylosis were enrolled for testing using a commercial A. vasorum antigen detection test. In addition, we collected information on potential risk behaviors for acquiring A. vasorum infection - eating potential intermediate hosts and paratenic hosts - among the dogs, using a questionnaire for dog owners. Moreover, we surveyed knowledge about A. vasorum among veterinarians authorized to work in Estonia. None (0.0%, 95% confidence interval 0.0-2.6) of the 114 dogs included in the study tested A. vasorum antigen positive. Two (2.0%) of the 102 dogs included in the risk behavior analysis had been seen to eat slugs and/or snails, and this behavior was considered possible for further 17 (16.7%) of the dogs. Four (3.9%) of the dogs had been seen to eat frogs, and this behavior was considered possible for further 14 (13.7%) of the dogs. Thirty-eight (90.5%) of the 42 veterinarians who participated in the questionnaire survey selected the correct host and 28 (66.7%) selected the correct vectors of the parasite, from the provided options. Our results indicate that A. vasorum was either not established or not common in dogs in Estonia in 2018-2019, but this needs to be interpreted with caution due to the limited sample size, possible false negative results in recently infected dogs and the limited sensitivity of the test applied. Most local veterinarians seemed to know the parasite, and this awareness and knowledge among veterinarians should be maintained and further improved. Taken the presence of the parasite in local wildlife, it is prudent to include A. vasorum infection in the list of differential diagnoses for dogs with clinical signs that could be suggestive of canine angiostrongylosis in Estonia.

The current situation of Angiostrongylus vasorum in Romania: a national questionnaire-based survey

Background

Angiostrongylus vasorum (Nematoda, Metastrongyloidea) is a vascular nematode that resides in the pulmonary arteries and the right side of the heart of a wide variety of carnivores, with an indirect life cycle using coprophagic gastropods as intermediate hosts. For domestic dogs, the infection with A. vasorum can be asymptomatic, but more frequently, it is associated with a wide range of clinical manifestations like cardio-respiratory signs, bleedings, neurological signs, and ocular problems which can lead to death when not treated accordingly. Angiostrongylosis was confirmed for the first time in Romania in red foxes (Vulpes vulpes) in 2017 and two years later a seroepidemiologic study was conducted among domestic dogs. However, to this date, no clinical canine angiostrongylosis cases were published in Romania. The aim of the present paper was to evaluate the knowledge about canine angiostrongylosis among veterinarians in Romania and to update the distribution of this disease using a national wide anonymous questionnaire.

Results

Overall, 147 unique responses were submitted, from 31 out of 42 counties. Twelve veterinarians (8%) from 8 counties (26%) acknowledged diagnosing a case of angiostrongylosis including 5 from the Bucharest and 1 from each of the remaining seven counties. All affected dogs had respiratory distress, 75% suffered cardiopathy, 16% coagulopathies and 8% neurological signs. Case diagnosis was based mostly on larval detection by coprology (67%) and serological antigen detection test (42%).

Conclusions

Romanian veterinarians are aware of canine angiostrongylosis and a significant number have clinical experience with the disease. Epidemiological studies are now needed to assess its distribution in the country, and further efforts are required to improve understanding of the disease, its diagnostic and treatment methods among veterinarians.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-03034-1.

Co-Occurrence of Domestic Dogs and Gastropod Molluscs in Public Dog-Walking Spaces and Implications for Infection with Angiostrongylus vasorum: A Preliminary Study

Simple Summary

Angiostrongylus vasorum is a serious parasitic disease increasing in range and prevalence in Europe. The parasite passes through land slugs and snails before it can infect dogs but contact between dogs and these intermediate hosts is not well studied. We surveyed dogs and slugs/snails in parks and on streets in an urban A. vasorum hotspot area in southern England, United Kingdom, with the aim of determining the conditions under which they overlap. We counted 1672 slugs/snails and 763 dogs across seven sites. We found that habitat types in which the hosts were present differed, with dogs occurring 15× more often on hard surfaces (e.g., concrete) than woodland/scrub, but also occurring on natural grassland. Large numbers of slugs/snails were present 5.82× more often in woodland/scrub and natural grassland than on hard surfaces. Slug and snail species at risk of a greater likelihood of infection with A. vasorum were present 65.12× more often in woodland/scrub and 62.17× more often in amenity grassland than other habitats. The results suggest that contact between dogs and slugs/snails is most likely in amenity and natural grassland but that infection risk with A. vasorum is greatest in amenity grassland and woodland/scrub.

Abstract

Angiostrongylusvasorum is a helminth parasite of domestic dogs that is increasing in range and prevalence. Its lifecycle requires terrestrial gastropod mollusc (“gastropod”) intermediate hosts, but research is lacking regarding contact risk in situ. We studied co-occurrence between dogs and gastropods in dog-walking spaces in an A. vasorum hotspot in southern England, United Kingdom, with the aim of quantifying environmental and spatio-temporal overlap. We surveyed 390 quadrats and 180 point-counts along 3 km transects at seven sites, yielding 1672 gastropod and 763 dog observations. Common gastropods comprised Arion, Cornu, Monacha, Deroceras, Tandonia, Cochlicella, and Trochulus species. Habitat was the most important factor structuring both gastropod and dog presence and abundance. Likelihood ratio comparisons from conditional probability trees revealed that dogs were 15× more likely to be present on hardstanding surfaces than other habitats but were also present on natural and amenity grassland. Presence of gastropod species associated with high A. vasorum prevalence was 65.12× more likely in woodland/scrub and 62.17× more likely in amenity grassland than other habitats. For gastropods overall, high abundance was 5.82× more likely in woodland/scrub and natural grassland. The findings suggest co-occurrence is highest in amenity and natural grassland, but infection risk is greatest in amenity grassland and woodland/scrub.

Rodent helminths in fragmented Atlantic Forest areas in the western region of the state of Paraná

Rodents are small mammals that can be parasitized by various helminths. This study aimed to identify and describe the ecological indicators of infection in rodents captured in fragments of the Atlantic Forest in the western region of Paraná State, Brazil. Sixty-eight specimens of five rodent species were collected, necropsied, and inspected in search of helminths. The parasites were stored in 70% ethanol, morphologically identified, and counted for calculation of infection indicators. Fourteen species of helminths and one species of Crustacea were recorded: ten in Akodon montensis, four in Mus musculus, two in Thaptomys nigrita, two in Oligoryzomys nigripes, and one in Euryoryzomys russatus. The registered species of parasites were: Rodentolepis akodontis, Angiostrongylus sp., Protospirura numidica criceticola, Trichuris navonae, Syphacia alata, Syphacia criceti, Syphacia evaginata, Trichofreitasia lenti, Stilestrongylus aculeata, Stilestrongylus eta, Stilestrongylus gracielae, Stilestrongylus franciscanus, Stilestrongylus moreli, Stilestrongylus sp., and Pentastomida gen. sp. A positive correlation between the intensity of infection of T. navonae and T. lenti was observed with the body condition index of the host A. montensis. For all species, this study represents a new register of locality, and for eight of them a new host.

Autochthonous Angiostrongylus cantonensis, Angiostrongylus vasorum and Aelurostrongylus abstrusus infections in native terrestrial gastropods from the Macaronesian Archipelago of Spain

The presence of zoonotic relevant Angiostrongylus cantonensis infections has recently been reported in rat final hosts and gastropod intermediate hosts in Tenerife, Spain. However, data on A. cantonensis, Angiostrongylus vasorum and Aelurostrongylus abstrusus prevalences in endemic gastropods for other islands of the Macaronesian Archipelago are still missing. In order to fill this gap, we conducted an epidemiological study on terrestrial native slug (Plutonia lamarckii) and snail (Cornu aspersum, Theba pisana, Rumina decollata) species in 27 selected locations of Tenerife, Gran Canaria, El Hierro, Lanzarote, La Palma and Fuerteventura. Overall, 131 terrestrial gastropods were collected in winter/spring season 2018/2019 and examined for the presence of metastrongyloid lungworm larvae via artificial digestion. The current data revealed a total prevalence of 4.6% for A. vasorum, 3.8% for A. abstrusus and 0.8% for A. cantonensis. In Tenerife, three lungworm species were detected, thereby re-confirming A. cantonensis endemicity for this island. Prevalences of snails (C. aspersum) originating from El Hierro were 5% for A. abstrusus and 15% for A. vasorum, respectively, with larval burdens up to 290 larvae per specimen. This epidemiological study indicates the presence of human, canine and feline lungworm species in Macaronesia, Spain. The current data-particularly those on anthropozoonotic A. cantonensis-call for a regular large-scale monitoring on intermediate hosts, paratenic hosts and definitive hosts to prevent further spread of lungworm-related diseases in humans and animals.

Molecular Detection of Gurltia paralysans by Semi-Nested PCR in Cerebrospinal Fluid and Serum Samples from Domestic Cats (Felis catus)

Simple Summary

Feline gurltiosis is a parasitic myelopathy caused by Gurltia paralysans. This nematode infects domestic cats without distinction of sex, breed or age, invading the venous system of the spinal leptomeninges and causing vascular congestion that mainly produces paralysis of the pelvic limbs, among other clinical signs of chronic myelopathy. To date, the definitive diagnosis of feline gurltiosis is only possible through post-mortem analysis that shows the location of the parasite in the vasculature of the spinal cord. For this reason, this investigation aimed to detect G. paralysans DNA, via semi-nested PCR, in samples of cerebrospinal fluid and serum from 12 domestic cats from potentially endemic areas in southern Chile, with compatible signs of feline gurltiosis. The presence of G. paralysans-specific DNA was detected in the cerebrospinal fluid of four out of nine cats and the sera of seven out of seven cats. These results allow us to suggest the implementation of a semi-nested PCR technique as a routine diagnostic test for early and timely detection of feline gurltiosis.

Abstract

Gurltia paralysans is an angio-neurotropic metastrongyloid nematode that infects domestic and wild cats, invading the veins of the subarachnoid space of the spinal cord and mainly causing progressive paralysis of the pelvic limbs. The definitive diagnosis of feline gurltiosis can only be achieved by post-mortem examination that reveals the presence of the nematode in the spinal cord vein vasculature. An early diagnosis with conclusive results is required since laboratory and imaging findings are not sufficient. Therefore, the purpose of this study was to detect the presence of G. paralysans, via semi-nested PCR, in samples of cerebrospinal fluid (CSF) and the sera of domestic cats naturally infected with the parasite. A total of 12 cats with a diagnosis suggestive of feline gurltiosis were selected, and they underwent a complete neurological and imaging examination. DNA samples were analysed by semi-nested PCR, with universal (AaGp28Sa1/AaGp28Ss1) and specific (Gp28Sa3/Aa28Ss2) primers, for G. paralysans (G. paralysans 18S rRNA gene, partial sequence; ITS 1, 5.8S rRNA gene, and ITS 2, complete sequence; and 28S rRNA gene, partial sequence) and Aelurostrongylus abstrusus, obtaining amplifications of 356 and 300 bp, which indicated the presence or absence of nematode DNA, respectively. The presence of G. paralysans was detected in the CSF of four out of nine cats, and the sera of seven out of seven cats. In the sera analysis of five out of seven cats, a mixed infection with A. abstrusus was found, despite no alterations of the respiratory tract being observed during the necropsies. It is proposed that serum samples could be more effective than CSF in detecting the parasite by PCR analysis. Sequencing analysis showed high percentages of identity with G. paralysans, which indicated the feasibility of detection and the sensitivity/specificity of the method used, suggesting the implementation of semi-nested PCR as a routine diagnostic test for early and timely detection of feline gurltiosis.

First case of a natural infection in a domestic cat (Felis catus) with the canid heart worm Angiostrongylus vasorum

Cardiopulmonary nematodes in cats include different parasite species affecting feline lungs and the heart, with the metastrongyloid Aelurostrongylus abstrusus being the most frequent feline lungworm worldwide. The present case report describes an 11-month-old male neutered European short hair cat which presented with generalised subcutaneous oedema and pleural and peritoneal effusions. According to clinical examination, abdominal imaging and laboratory analyses, a tentative diagnosis of severe glomerulopathy with massive proteinuria was made. Due to worsening of the clinical signs despite therapeutic interventions and a poor prognosis, the cat was euthanised. Necropsy and histological examinations revealed severe bilateral collagenofibrotic glomerulopathy, generalised oedema and a focal verminous pneumonia with thrombosis in arterial lung vessels containing nematode cross sections. A serum sample was tested for the presence of antibodies against the cat lungworm A. abstrusus, resulting negative. Genetic analyses confirmed the presence of nematode DNA; after exclusion of common lung and heart parasites occurring in cats, DNA of the canid heart worm nematode Angiostrongylus vasorum was identified. This is the first description of a naturally occurring infection with A. vasorum in a cat. Previous experimental studies demonstrated the development of adult male and female A. vasorum worms containing eggs in cats, but no larval excretion in the faeces. Although cats did not become patent, A. vasorum infections were clinically relevant. As A. abstrusus and A. vasorum are both gastropod transmitted nematodes, they may share the same intermediate hosts within overlapping areas. In addition, especially chronic A. abstrusus infected cats become non-patent and do not excrete L1. Considering that patent A. vasorum infections are widespread in the dog and fox population in Switzerland (and several other countries) but are apparently not patent in cats, we cannot exclude that infections with A. vasorum may occur more frequently than expected.

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Angiostrongylus vasorum is a cardiopulmonary nematode of dogs and other canids

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First natural infection of a cat (Felis catus) with Angiostrongylus vasorum

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Histological nematode sections identified in pulmonary arteries, confirmed by PCR

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Aberrant, non-patent infection in the cat with clinical relevance

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Such infections may occur more frequently particularly in highly endemic areas

The first seroepidemiological survey for Angiostrongylus vasorum in domestic dogs from Romania

Background

Angiostrongylus vasorum is a metastrongyloid nematode localized in the right heart and the pulmonary arteries of domestic dogs. The number of reports in Europe has recently increased, presumably as a consequence of a growing awareness among clinicians, animal owners and researchers, but also due to a growing incidence and territorial spread. So far, no studies have been conducted to assess the prevalence and distribution of A. vasorum in domestic dogs in Romania, and the awareness among veterinarians is limited or absent. The aim of the present study was to evaluate the countrywide seroprevalence of circulating antigens of A. vasorum and specific antibodies against A. vasorum in domestic dogs from Romania.

Methods

Between November 2016 and July 2017, blood was sampled from a total of 1545 domestic dogs from 23 counties of Romania. Details about their gender, age, breed, housing, use and origin were collected. All serum samples were tested for the presence of A. vasorum circulating antigens (AG) using monoclonal and polyclonal antibodies in a sandwich ELISA. Additionally, a sandwich ELISA using A. vasorum adult somatic antigen purified by monoclonal antibodies was used for specific antibody (AB) detection.

Results

A total of 33 dogs (2.14%, 95% CI: 1.82–3.56%) were seropositive for A. vasorum antigen or antibodies against the parasite. Three dogs were positive for antigen only (0.19%, 95% CI: 0.07–0.57%) and 30 dogs (1.94%, 95% CI: 1.36–2.76%) were positive for antibodies only. No dog was positive for both tests. The overall prevalence (AB or AG) and the AB prevalence were significantly higher in pure breed dogs compared to mixed breeds and mongrel dogs (P < 0.05) and in shepherd dogs compared to other groups (P < 0.05). There was no significant difference between males and females, between urban and rural dogs, between dogs with unrestricted access and with restricted access to the environment, and between dogs living outdoors and indoors.

Conclusions

Our data suggest that the disease is present in Romania in dogs, as it was previously demonstrated in foxes. However, so far, no clinical case has been reported in the country and this may be related to a low awareness among vets.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3481-0) contains supplementary material, which is available to authorized users.

A grid-cell based fecal sampling scheme reveals: land-use and altitude affect prevalence rates of Angiostrongylus vasorum and other parasites of red foxes (Vulpes vulpes)

In view of the role of foxes as a reservoir for Angiostrongylus vasorum, a nematode of the heart and lungs of dogs and foxes, its occurrence across Switzerland was investigated in foxes applying a standardized sampling scheme for fox fecal samples. In 72 study areas, which consisted of three 1-km² grid cells, a total of 1481 samples were collected by walking transects following linear features in the terrain, and analyzed by a flotation-sieving method. The overall prevalence rate of A. vasorum in fecal samples was 8.8% (95% confidence interval, CI 7.4-10.3%), being significantly higher in the Swiss Plateau (11.4%, CI. 9.4-13.8%) compared with other bioregions, and more prevalent in areas with less than 50% of cultivated land (p = 0.043). Prevalence rates increased with decreasing altitudes being significantly higher below 400 m above sea level (20.6%, 95% CI 15.2-26.9%), while all samples collected above 900 m asl were negative. Eggs of Toxocara sp. (12.1%), Taeniidae (10.5%), Capillaria spp. (8.3%), Trichuris vulpis (5.5%), hookworms (5.3%), Toxascaris leonina (1.3%) and Strongyloides sp. (0.4%) were furthermore identified. Taeniid eggs were positively and Capillaria spp. negatively associated with the amount of cultivated land. The prevalence rates based on our fecal analyses were generally lower compared with previous studies from Switzerland which were based on fox necropsies. However, the grid cell-based sampling scheme with replicable transects for fox feces collection proved to be a suitable, non-invasive method for parasitic large-scale surveys providing information on the relative infectious pressure for the local dog population.

The invasive giant African snail Lissachatina fulica as natural intermediate host of Aelurostrongylus abstrusus, Angiostrongylus vasorum, Troglostrongylus brevior, and Crenosoma vulpis in Colombia

BACKGROUND

Several metastrongyloid lungworms are unreported pathogens in Colombia. Angiostrongylus vasorum and Crenosoma vulpis target the cardiopulmonary system of domestic and wild canids. Aelurostrongylus abstrusus and Troglostrongylus brevior infect felids and considering that six wild felid species exist in Colombia, knowledge of feline lungworm infections is important for their conservation. The zoonotic metastrongyloids Angiostrongylus costaricensis and Angiostrongylus cantonensis can cause severe gastrointestinal and neurological diseases. Angiostrongylus costaricensis has been reported in Colombia, while Ang. cantonensis is present in neighbouring countries. Research on the epidemiology of metastrongyloids in Colombia and South America more broadly requires evaluating the role that gastropods play as intermediate hosts in their life cycles. This study assessed the prevalence of metastrongyloid larvae in populations of the invasive giant African snail, Lissachatina fulica, in Colombia.

METHODOLOGY/PRINCIPAL FINDINGS

A total of 609 Lissachantina fulica were collected from 6 Colombian municipalities. The snails were then cryo-euthanized, artificially digested and the sediments examined microscopically for the presence of metastrongyloid larvae. Based on morphological characteristics 53.3% (56/107) of the snails from Puerto Leguízamo (Department of Putumayo) were infected with Ael. abstrusus larvae, 8.4% (9/107) with Ang. vasorum larvae, 6.5% (7/107) with T. brevior larvae and 5.6% (6/107) with C. vulpis larvae, being the region with highest prevalences of the four species. Snails from Andes (Department of Antioquia) and Tulúa (Department of Valle del Cauca) were positive for Ang. vasorum larvae with a prevalence of 4.6 (11/238) and 6.3% (4/64), respectively. Species identifications were confirmed by PCR and sequencing.

CONCLUSIONS/SIGNIFICANCE

This epidemiological survey reports for first time the presence of Ael. abstrusus, T. brevior, C. vulpis and Ang. vasorum in L. fulica in a number of regions of Colombia.

Molecular detection of Angiostrongylus vasorum in gastropods in Surrey, UK

Surrey, a county in southern England, is a hot spot for angiostrongylosis in domestic dogs but there have been no investigations into the intermediate hosts of Angiostrongylus vasorum in this area. This study aimed to determine the prevalence of A. vasorum in gastropods in Guildford, the most populous town in Surrey, and to ascertain which gastropod species can act as intermediate hosts for A. vasorum. Gastropods (n = 97) were sampled in six locations, representing urban, suburban and rural environments, and identified to species based on morphological features. A PCR assay was used to detect A. vasorum DNA in gastropod tissue and the species of infected specimens was confirmed by sequencing of mitochondrial genes. 4.1% (4/97) of sampled gastropods and 9.1% (4/44) of sampled slugs were A. vasorum positive. Infected gastropod species were Arion rufus (n = 3) and Deroceras invadens (n = 1), the first description of the latter species as a potential intermediate host for A. vasorum. Two infected slugs were sampled in urban environments and two in suburban environments. The results demonstrate that there is a risk of transmission of A. vasorum to domestic dogs from the gastropod population in urban and suburban areas of Guildford.

Detection of Toxocara canis DNA in tissues of experimentally infected mice

The main etiological agent of toxocariasis is the helminth Toxocara canis. Several difficulties are found in the diagnosis of this disease, because of nonspecific clinical signs and possible cross-reactions that may occur in the available test, the indirect ELISA. Therefore, molecular diagnosis has been indicated as an alternative to conventional diagnosis. The purpose of this study was to evaluate the polymerase chain reaction (PCR) technique for the identification of T. canis in tissues of experimentally infected mice. To this end, nine mice were inoculated with 1500 embryonated eggs and were divided into two groups, the first euthanized 48 h (G1) and the other 30 days post inoculation (G2). Lungs, brain, liver and blood were collected from all the animals for DNA Extraction and tissue digestion, also was collected blood samples for DNA extraction and ELISA test (serum). Toxocara canis DNA was identified in all the inoculated animals using the ITS-2 target gene. The PCR test successfully identified the parasite in the brain, lung and liver of the animals euthanized 48 h PI and 30 days PI. This technique yielded good results in the identification of the parasite in the brain, being more sensitive than the method for the recovery of larvae, in the group with acute infection (48 h PI). The infection was confirmed by PCR within 48 h after infection, while the ELISA indicated serological conversion occurred only 14 days after inoculation. This study demonstrates the ability of PCR to identify T. canis in the liver, lungs and brain during acute and chronic infection.

Genetic diversity and population structure of Angiostrongylus vasorum parasites within and between local urban foxes (Vulpes Vulpes)

Angiostrongylus vasorum is a nematode parasite of the pulmonary arteries and heart that infects domestic and wild canids. Dogs (Canis familiaris) and red foxes (Vulpes vulpes) are the most commonly affected definitive hosts. Recent studies suggest that angiostrongylosis is an emerging disease, and that red foxes may play an important role in the epidemiology of the parasite. Genetic analyses of parasites collected from dogs and foxes throughout Europe have shown that the same parasite haplotypes are commonly shared between different host species. However, the extent of genetic diversity within local A. vasorum populations and individual hosts is unknown. The objective of the present study was to assess the occurrence of genetic diversity among A. vasorum (a) recovered from different foxes within the Greater London area (a localised population, single worm per fox dataset); and (b) hosted within single foxes (multiple worms per fox dataset). During 2016, A. vasorum worms were collected from foxes culled for other purposes in London. DNA was extracted from each parasite and a partial fragment of the mitochondrial cytochrome oxidase subunit 1 (mtCOI) gene was amplified and sequenced. Sequences from the single worm dataset were compared with those published elsewhere. Combined, 19 haplotypes were described of which 15 were identified from foxes found in London, indicating that considerable genetic diversity can be detected within a local geographic area. Analysis of the multiple worm dataset identified 22 haplotypes defining worms recovered from just six foxes, emphasising the relevance of wild canines as reservoirs of genetic diversity. This is the first study to explore the genetic complexity of individual fox-hosted A. vasorum populations.

Angiostrongylus vasorum and Aelurostrongylus abstrusus: Neglected and underestimated parasites in South America

The gastropod-borne nematodes Angiostrongylus vasorum and Aelurostrongylus abstrusus are global causes of cardio/pulmonary diseases in dogs and cats. In the last decade, the number of reports on canine and feline lungworms has increased in several areas of Europe and North America. The unspecific clinical signs and prolonged course of these diseases often renders diagnosis challenging. Both infections are considered as emerging and underestimated causes of disease in domestic pets. In South America, little information is available on these diseases, apart from occasional reports proving the principle presence of A. vasorum and A. abstrusus. Thus, the purpose of this review is to summarize reports on infections in both domestic and wildlife animals in South America and to increase the awareness on gastropod-borne metastrongyloid parasites, which also include important zoonotic species, such as A. cantonensis and A. costaricensis. This review highlights the usefulness of diagnostic tools, such as the Baermann funnel technique, serology and PCR, and proposes to include these routinely on cases with clinical suspicion for lungworm infections. Future national epidemiological surveys are recommended to be conducted to gain a deeper insight into the actual epidemiological situation of gastropod-borne parasitoses in South America.

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

INTRODUCTION

Angiostrongyliasis is a disease caused by Angiostrongylus nematodes that is present worldwide. The infections with the highest impact on human and animal health are caused by A. cantonensis, A. costaricensis, and A. vasorum. Clinical forms of the disease in humans are eosinophilic meningitis and abdominal angiostrongyliasis, while the most common effect on dogs are cardiopulmonary damages. It is deemed as an emerging disease as the result of the global dissemination of the African snail Lissachatina fulica, an intermediary host of these parasites. The few diagnostic methods for Angiostrongylus spp. are unspecific, costly, and not very sensitive. It is urgent to develop a sensitive, specific and accessible diagnostic tool for the control of human and animal angiostrongyliasis.

OBJECTIVE

To develop a qPCR multiple test to identify the three pathogenic species of Angiostrongylus.

MATERIALS AND METHODS

Through a bio-informatic analysis, we selected a sequence of the ITS-2 region of the Angiostrongylus genome to guarantee the specificity of primers and probes. We extracted DNA from adult parasites as positive control, and from larvae using the DNeasy Blood&Tissue® kit. Quantitative PCR reactions were conducted on a Smartcycler Cepheid® thermocycler using a master mix QuantiTect® kit. DNA from human beings, other parasites and the African snail was used as negative control.

RESULTS

The threshold cycle values for positive DNA controls were: 21 for Angiostrongylus cantonensis, 22 for A. costaricensis, and 31 for A. vasorum. In negative controls, the threshold cycle was zero. qPCR showed an amplification efficiency of 2 (100%).

CONCLUSIONS

A multiple qPCR was standardized at the laboratory for three clinically significant species of Angiostrongylus.

Molecular identification of potential intermediate hosts of Aulonocephalus pennula from the order Orthoptera

Aulonocephalus pennula is a heteroxenous nematode that commonly infects a declining game bird, the northern bobwhite quail (Colinus virginianus). There is a lack of information on the life cycle of A. pennula and the potential effects of infection on bobwhites. In order to better understand the life cycle of this parasite, various species from the order Orthoptera were collected from a field site in Mitchell County, Texas. Using polymerase chain reaction (PCR), nine potential intermediate hosts were identified from the 35 orthopteran species collected. Later, ten live specimens were collected to identify larvae within the potential intermediate hosts. Larvae were present in three of these and were sent for sequencing. Similarly, the presence of larvae was confirmed from extra tissues of samples identified as positive with PCR. This was the first study to document potential intermediate hosts, but future studies are needed to confirm that these species are capable of transmitting infection to bobwhite. However, this study demonstrates that PCR has increased sensitivity and may be a valuable tool when determining intermediate hosts.

Prevalence of Angiostrongylus vasorum, Aelurostrongylus abstrusus and Crenosoma vulpis larvae in native slug populations in Germany

Metastrongyloid parasites represent sparsely studied parasites of dogs and cats in Germany. Recent European surveys indicate that these parasites are spreading in Europe. Actual data on prevalence of Angiostrongylus vasorum in dogs and foxes reveal several endemic foci in Germany. However, actual data on the prevalence of A. vasorum and other metastrongyloid lungworm larvae in a wide range of slug and snail intermediate hosts, such as Arion lusitanicus, are missing for Germany. To fill this gap, we conducted an epidemiological survey on native German slugs in selected regions of Hesse and Rhineland-Palatinate. The focus was on slugs, because in study areas slugs appear to be more abundant than snails. Slugs were collected throughout different seasons of the year in areas that were previously proven to be hyperendemic for A. vasorum fox infections. Overall, a total of 2701 slugs were collected and examined for lungworm larvae via artificial digestion. The number of A. vasorum larvae per slug varied considerably (1-546 larvae per specimen). Some hotspot areas with high A. vasorum prevalence in slugs (up to 19.4%) were identified. The overall A. vasorum prevalence varied with season with largest number of slugs infected in summer (9.1%) and lowest number in winter (0.8%). The current study revealed a total A. vasorum prevalence of 4.7% in slugs based on microscopic analyses. Confirmation of lungworm species was made by specific duplex-real-time PCRs. Hence, these data demonstrate that final hosts are at a permanent risk for A. vasorum infections during all seasons when living in investigated areas. Besides A. vasorum, other lungworm larvae were also detected, such as Crenosoma vulpis (the fox lungworm, 2.3%) and Aelurostrongylus abstrusus (feline lungworm, 0.2%).

Prevalence survey on lungworm (Angiostrongylus vasorum, Crenosoma vulpis, Eucoleus aerophilus) infections of wild red foxes (Vulpes vulpes) in central Germany

Background

Angiostrongylus vasorum, Crenosoma vulpis and Eucoleus aerophilus are a source of increasing concern, potentially causing significant pulmonary and severe cardiac/systemic diseases in domestic dogs and wild canids, especially red foxes (Vulpes vulpes). To investigate the prevalence and geographical distribution of these parasites in central Germany, a total of 569 foxes were examined by dissection.

Methods

Pluck (heart and lung) and faecal samples of red foxes were collected from three regions of Germany. Lungs, hearts and adjacent vessels were processed for adult nematode detection. Parasitological diagnoses of faecal samples were performed by SAF technique, Giardia- and Cryptosporidium-Coproantigen-ELISAs and by a duplex copro-PCR for the detection of A. vasorum and C. vulpis DNA.

Results

Foxes originated from three Federal States of central Germany: Thuringia (n = 359); Rhineland-Palatinate (n = 121) and Hesse (n = 89). High prevalences for all three nematodes were detected, with E. aerophilus (69.4%; 395/569), followed by C. vulpis (32.3%; 184/569) and A. vasorum (14.1%; 80/569). In case of A. vasorum, prevalences varied significantly between Federal States, with the highest prevalence of 27.3% in Rhineland-Palatinate, followed by 19.1% and 8.4% in Hesse and Thuringia, respectively. The presence of A. vasorum in fox populations showed a rather patchy distribution, increasing from north-eastern to south-western regions. Analyses on C. vulpis revealed prevalences of 35.1%, 30.3% and 25.6% (Thuringia, Hesse and Rhineland-Palatinate, respectively). The most prevalent lungworm nematode was E. aerophilus, with a prevalence of 75.2%, 71.9% and 66.9% (Rhineland-Palatinate, Hesse and Thuringia, respectively) and an almost area-wide equal distribution. Significant differences for single parasite prevalences within geographical regions of the Federal States could be detected whilst no correlation between age or gender and parasite occurrence was estimated. Weak seasonality for the winter months for A. vasorum, stronger correlation to spring and late summer for C. vulpis and no correlation to any season for E. aerophilus were detected. The method of dissection revealed a significantly higher sensitivity for C. vulpis when compared with the results of the duplex copro-PCR.

Conclusions

A sylvatic cycle was confirmed for all three lungworm nematodes in the examined area. The prevalences for all three lungworm nematodes are some of the highest recorded so far in German foxes. The data suggest that A. vasorum might be spreading from south-western to north-eastern parts of Germany.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2672-4) contains supplementary material, which is available to authorized users.

Canine angiostrongylosis in Sweden: a nationwide seroepidemiological survey by enzyme-linked immunosorbent assays and a summary of five-year diagnostic activity (2011-2015)

Background

For the first time in Sweden, Angiostrongylus vasorum was detected on the island of Sydkoster in foxes and dogs in 2003. After sporadic detection of the parasite in foxes in southern Sweden, the first positive canine faecal sample on the mainland was found in 2011. Since then a total of 2882 faecal samples have been analysed with the Baermann test at the National Veterinary Institute (SVA) during the years 2011–2015; 20 of them being positive. Contemporaneously, of over 525 fox necropsies, only three were found to be infected. To gather a more accurate knowledge of A. vasorum occurrence in Sweden, a large scale seroepidemiological survey was performed and totally 3885 serum samples from dogs were tested for both the presence of circulating antigens and of specific antibodies to A. vasorum.

Results

In total, 0.10% (n = 4, 95% Confidence Intervals, CI 0.03–0.26%) of the dogs were positive for both antigen and antibodies, whereas 0.51% (n = 20, CI 0.31–0.79%) of the tested dogs were only antigen positive and 0.88% (n = 34, CI 0.61–1.22%) only positive for specific antibodies. Seropositive animals, as well as the majority of A. vasorum-positive faecal samples tested during the same period, were spread over central and southern Sweden. Annual prevalence of positive faecal dog samples and of necropsied A. vasorum positive foxes (coming from southern Sweden) varied from 0.3 to 0.9% (overall: 0.7%, CI 0.4–1.1%) and 0.0 to 1.4% (overall: 0.3%, CI 0.1–0.9%), respectively.

Conclusions

The findings confirmed that A. vasorum has become established in various geographical areas of central and southern Sweden. Veterinarians and dog owners should be aware of the potential risks of infection in large areas of the country, since canine angiostrongylosis may be a fatal disease if left untreated.

Meerkats (Suricata suricatta), a new definitive host of the canid nematode Angiostrongylus vasorum

Angiostronglyus vasorum is a cardiopulmonary nematode infecting mainly canids such as dogs (Canis familiaris) and foxes (Vulpes vulpes). Natural infections have also been reported in mustelids and red pandas (Ailurus fulgens fulgens). We report the occurrence of natural A. vasorum infections in a group of captive meerkats (Suricata suricatta), housed at a university facility in Switzerland. A. vasorum first-stage larvae (L1) were initially identified in a pooled faecal sample. Individual samples, investigated with the Baermann-Wetzel technique, revealed that 41% (7/17) of the meerkats were infected, with ranges of 2–125 L1/g faeces. PCR and sequencing of part of the ITS-2 region resulted in 100% identity with A. vasorum. Infected animals did not show clinical signs. One meerkat died two days after diagnosis. Upon necropsy one adult specimen was recovered; histological examination of the lung revealed granulomatous pneumonia caused by A. vasorum larvae and eggs as well as intima and media hyperplasia and isolated arteriosclerosis of larger lung vessels. However, the cause of death was a spleen rupture with associated blood loss. All meerkats were topically treated with 10 mg imidacloprid/2.5 mg moxidectin per animal, after which they became negative in all follow up faecal examinations. Potential intermediate (gastropods) and paratenic hosts (birds) were collected from within or outside the meerkats enclosure. Gastropods were examined by PCR and bird samples by digestion. Four out of 193 (2.1%) gastropod samples were positive for A. vasorum, whereas none of the bird samples were positive. Meerkats, belonging to the Herpestidae, therefore are suitable definitive hosts for A. vasorum, with production and excretion of live L1. Meerkats kept in captivity in areas where A. vasorum is endemic and with potential contact to intermediate hosts are at risk of infection. Regular faecal examinations including Baermann-Wetzel technique should be considered.

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Meerkats are suitable definitive hosts for Angiostrongylus vasorum.

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This is the first case of A. vasorum in the Herpestidae family.

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A. vasorum larvae and eggs caused granulomatous pneumonia in an infected meerkat.

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2% of gastropods around the meerkats enclosure were positive for A. vasorum L3.

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Captive animal species in areas where A. vasorum is endemic are at risk of infection.

Redescription and first molecular characterization of the little known feline neurotropic nematode Gurltia paralysans (Nematoda: Metastrongyloidea)

Gurltia paralysans is a poorly documented metastrongyloid nematode of cats, which mainly parasitizes the veins in the spinal cord subarachnoid space and parenchyma. Parasitic paraparesis caused by G. paralysans is a lesser-known spinal cord disease affecting domestic and wild felids of South America. Regions where feline gurltiosis is endemic include the southern parts of Chile and Argentina. Intra vitam diagnosis of feline gurltiosis remains challenging and is based primarily on neurological signs and the exclusion of other ethiologies for feline myelopathies. In view of the lack of information in the literature for this neglected feline neurological parasitosis, we have undertaken a detailed redescription and molecular characterization to expand on the previously available details in the original descriptions by Wolffhügel in 1993. The specimens used in this study were collected from spinal cord lesions of gurltiosis-affected domestic cats. Female and male specimens were morphologically and morphometrically examined using light and scanning electron microscopy. Molecular characterization was performed by sequencing a partial region of the nuclear ribosomal DNA and cytochrome oxidase gene of this parasite, and phylogenetic trees were constructed from the 28S D2-D3 and ITS2 regions using the Maximum Likelihood method. Sequence matching and phylogenetic analysis with these new sequences were consistent with the morphological classification of G. paralysans being within the Metastrongyloidea superfamily, but no consistent relation to a specific metastrongyloid family. The newly developed G. paralysans-specific PCR described here not only provides a useful diagnostic tool for feline gurltiosis in domestic cats living in endemic areas, but could also be used in large-scale epidemiological surveys on the intermediate mollusk host and the final host. By combining the morphology, molecular, and phylogenetic data we have reliably identified G. paralysans and confirmed its taxonomic status within the Metastrongyloidea.

Impact of heat treatment on antigen detection in sera of Angiostrongylus vasorum infected dogs

Background

In the last decade serological tests for detection of circulating Angiostrongylus vasorum antigen and specific antibodies have been developed and adopted for individual diagnosis and epidemiological studies in dogs. Although confirmed positive at necropsy, antigen detection was not possible in single experimentally, as well as naturally infected dogs, possibly due to immune complex formation. The aim of this study was to evaluate the effect of heat treatment on detection of A. vasorum antigen in sera of experimentally (n = 21, 119 follow-up sera) and naturally (n = 18) infected animals. In addition, sera of dogs showing clinical signs consistent with angiostrongylosis (n = 10), of randomly selected dogs (n = 58) and of dogs with other parasitic infections (n = 15) were evaluated. Sera were subjected to heat treatment at 100 °C after addition of 0.5 M EDTA (dilution 1:5) and tested with ELISAs for detection of circulating A. vasorum antigen before and after treatment.

Results

Between 5 and 11 weeks post-inoculation (wpi) the percentage of positive untreated samples (experimentally infected dogs) increased over time from 33.3 to 90%. Single samples were still negative between 12 and 15 wpi. Overall, between 5 and 15 wpi, 50.6% (45/89) of the available samples were seropositive. From 3 to 6 wpi EDTA/heat treatment caused a change in 8/34 (23.5%) of the samples, with most (n = 6, 17.6%) converting from positive to negative. In contrast, from 7 to 10 wpi, treatment induced a change in 19/52 (36.5%) samples, with all but one converting from negative to positive. Thirteen of 18 naturally infected dogs were antigen positive before and 15 after EDTA/heat treatment, respectively. Untreated samples of 3 dogs with suspected angiostrongylosis were antigen positive, of which only one remained positive after EDTA/heat treatment. One of 58 untreated random samples was antigen positive; this sample became negative after treatment, while another turned positive. One of 15 dogs infected with other parasites than A. vasorum was positive before but negative after treatment.

Conclusion

Although heat treatment improves A. vasorum antigen detection between 7 and 10 wpi by immune complex disruption, we do not recommend systematic pretreating sera because of reduced antigen detection between 3 and 6 wpi and impairment of antibody detection, if performed contemporaneously.

The effect of host age and inoculation dose on infection dynamics of Angiostrongylus vasorum in red foxes (Vulpes vulpes)

BACKGROUND

Infections and clinical cases of Angiostrongylus vasorum in dogs are found increasingly across Europe, thus rendering knowledge on its infection biology more important. We used red foxes as a carnivore model to examine the effect of host age and infection dose on the establishment of adult A. vasorum in single experimental infections.

METHODS

Fourteen juvenile and fourteen adult red foxes, free of metastrongyloid infections, were given a low (50) or high (200) dose of third-stage larvae (L3) of A. vasorum. Two groups of three foxes of each age group served as uninfected controls. Larval excretion by Baermann and blood parameters were followed for ten weeks. Worm counts were performed at necropsy by sequential perfusion, dissection and Baermann method.

RESULTS

The establishment rate (i.e. recovery in percentage of inoculation dose) of A. vasorum primary infections in red foxes was associated with host age and inoculation dose. In the low dose juveniles, 61% (range 52-72%) of the infection dose was recovered as worms in the pulmonary arteries and heart at necropsy while only 35% (21-50%) were recovered in the high dose. Corresponding establishment rates for adults were 39% (18-98%) and 8% (1-21%). In juveniles, a higher dose resulted in significantly higher adult worm counts, higher larval excretion and more pronounced pathophysiological changes, particularly in coagulation parameters. Earlier onset of patency was also found in the juveniles. In contrast, the larval excretion in high dose adults was very low and two infected animals never reached patency. However, a few adults showed only limited resistance as judged by excretion of larvae. The increase to very high larval excretion levels (> 4,000 larvae per g of faeces) after several months in a single animal, indicated that any potential acquired immunity does not affect worm fecundity.

CONCLUSIONS

Resistance to a primary A. vasorum infection was generally higher in older animals, and this age resistance was reflected in lower worm counts and reduced excretion of larvae. The juvenile red foxes were fully susceptible, as reflected in high establishment rates. Although severe clinical disease was never observed in the foxes, A. vasorum infections in red foxes appear to be chronic and moreover, to resemble infections in dogs. The results underline the red fox as a suitable model as well as natural reservoir for the parasite.

Trematode Fluke Procerovum varium as Cause of Ocular Inflammation in Children, South India

Larvae of this fluke are novel causes of granulomatous eye disease in children.

Trematodes are recognized as a group of emerging parasites in tropical countries. We identified a trematode as a cause of ocular granulomas that developed in children who bathed in ponds or rivers in South India. DNA was isolated from patients’ surgically excised granulomas and from the trematode cercariae (larvae) released by the snail Melanoidestuberculata in water in which the children bathed. Real-time and conventional PCRs were performed that targeted ribosomal DNA regions spanning the internal transcribed spacer 2 and 28S sequences of this trematode. The PCR-amplified products were subjected to bidirectional sequencing. Analysis of sequences for the granuloma samples and the trematode cercariae showed maximum sequence similarity with Procerovumvarium (family Heterophyidae). Our results confirmed the etiology of the ocular infection, implicating snail vectors as environmental risk factors for ocular parasitosis.

Comparative imaging of European eels (Anguilla anguilla) for the evaluation of swimbladder nematode (Anguillicoloides crassus) infestation

This study compares diagnostic imaging tools in detecting the parasitic swimbladder nematode Anguillicoloides crassus in Anguilla anguilla (L.) and focuses on ultrasound in an attempt to develop a non-destructive, field diagnostic test. Ultrasound use could allow the parasite to be diagnosed without decreasing the number of critically endangered European eels through post-mortem. In the preliminary study, eels were examined with computed radiography, computed tomography, magnetic resonance imaging, 14 MHz high-end ultrasound and 5 MHz low-end portable ultrasound, and the results were compared with post-mortem findings. This ultrasound scanning technique did not produce any promising results. A second batch of eels was examined using the same high-end and low-end ultrasounds, but employing a different scanning technique and comparing the results with post-mortem. This second study, scanning along the midline from below, allowed for the detection of anomalies associated with moderately infected animals. None of the eels used in this study were severely infected; thus, no conclusions can be made regarding the use of ultrasound in those animals. Overall, it was found that none of the techniques were useful in diagnosing mildly infected individuals; therefore, no single diagnostic imaging tool is sensitive enough to replace post-mortem for definite diagnosis.

Seroprevalence of circulating Angiostrongylus vasorum antigen and parasite-specific antibodies in dogs from Portugal

Angiostrongylus vasorum is a nematode that lives in the pulmonary arteries and right cardiac ventricle of domestic dogs and wild canids. It is increasingly being reported in several European countries and North America. This parasite induces inflammatory verminous pneumonia, causing severe respiratory disease in dogs. In some instances, coagulopathies, neurological signs and even death may occur. Scant data are available regarding the occurrence of A. vasorum in Portugal. Therefore, sera of 906 shelter dogs from North to South mainland Portugal were collected. ELISAs to detect A. vasorum circulating antigen and specific antibodies against this parasite were performed. A total of six dogs [0.66 %, 95 % confidence intervals (CI) 0.24–1.43] were positive for both A. vasorum antigen and antibody detection, indicating an active infection, and 12 dogs (1.32 %, CI 0.68–2.30) were A. vasorum antibody-positive only. Regions with antigen- and antibody-positive animals overlapped and were distributed over nearly all sampled areas in the country. This is the first large-scale ELISA-based serological survey for A. vasorum in dogs from Portugal. The endemic occurrence of A. vasorum in dogs from different geographical areas of Portugal is therefore confirmed.

Comparison of three methods for the detection of Angiostrongylus vasorum in the final host

Angiostrongylosis is potentially fatal parasitic nematode infection affecting dogs which can be difficult to diagnose. In recent years several microscopical, serological and molecular detection methods have been developed, however there are few studies that have compared the relative performance of these methods. Screening necropsy material from an opportunistic sample of 140 foxes (82 of which were considered to be infected with Angiostrongylus vasorum), indicated sensitivities of 84.1% for dissection and visual examination of plucks, 69.5% for nested PCR of an 18S rRNA fragment and 76.8% for a canine A. vasorum antigen detection test (IDEXX Angio Detect) of tissue fluid samples respectively. Agreement between the tests ranged from 45.6 to 79.7%. A novel nested PCR-RFLP for the detection and identification of canid lungworm spp. is described.

Detection of Angiostrongylus vasorum in Red Foxes (Vulpes vulpes) from Brandenburg, Germany

Angiostrongylus (A.) vasorum is a nematode that causes angiostrongylosis in domestic and wild canids. Red foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) are suspected of providing a wildlife reservoir for A. vasorum infections in pet dogs. To obtain data on the occurrence of A. vasorum in wildlife, red fox and raccoon dog carcasses (hunted or found dead) were collected from January to September 2009 in the Federal State of Brandenburg, Germany. Lung tissue samples were subjected to DNA extraction and examined for the presence of A. vasorum DNA by means of real-time PCR. A. vasorum DNA was detected in 11 out of 122 (9.0 %) lungs of red foxes and in none of the lung samples of raccoon dogs. These data suggest that red foxes are a reservoir of A. vasorum infections for pet dogs in this area.

Combined Serological Detection of Circulating Angiostrongylus vasorum Antigen and Parasite-specific Antibodies in Dogs from Hungary

The occurrence of the nematode Angiostrongylus vasorum, also known as the French heartworm, is increasingly being reported from various European countries. The adults of this parasite species live in the pulmonary arteries and right cardiac ventricle of wild canids and domestic dogs. Larval stages and eggs in the lungs induce inflammatory verminous pneumonia, causing severe respiratory disease in dogs. Furthermore, haematological and neurological signs and even death may occur. In Hungary, A. vasorum has been identified in red foxes, golden jackals and in two dogs and some slugs. In this first large-scale survey, 1247 sera from pet dogs were collected and tested by an ELISA for the detection of circulating antigen of A. vasorum and by a separate ELISA to detect specific antibodies against the parasite. A total of 1.36% (n = 17, 95 % confidence intervals, CI: 0.80 - 2.17 %) of the animals were positive in both ELISAs, while 1.76 % (n = 22, CI: 1.11 - 2.66 %) of the tested dogs were antigen-positive only and 2.73 % (n = 34, CI: 1.90 - 3.79 %) were positive for specific antibodies only. Regions with antigen- and antibody-positive animals overlapped and were distributed over nearly the whole sampled areas of the country. A considerable number of cases was observed in Budapest and also in the southern part of the country bordering Croatia, while in the most eastern part bordering Ukraine no positive samples were detected. These results confirm the endemic occurrence of A. vasorum in dogs originating from different parts of Hungary and the significant advantages of A. vasorum serology in epidemiological studies.

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

Background

Angiostrongylus 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.

Methods

The 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.

Results

There 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.

Conclusion

We 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.

Comparison of coprological, immunological and molecular methods for the detection of dogs infected with Angiostrongylus vasorum before and after anthelmintic treatment

Timely diagnosis of the nematode Angiostrongylus vasorum in dogs is important in view of severe and permanent lung and cardiovascular lesions that may occur. The performance of the classical Baermann coprological method was compared with ELISAs for the serological detection of circulating antigen and specific antibodies and with Polymerase chain reaction (PCR) performed on EDTA blood, feces and tracheal swabs of serial samples from experimentally inoculated dogs over 13 weeks post inoculation (wpi) (n = 16) and following anthelmintic treatment (n = 6). Patency was observed from 6.7 to 7.6 wpi in all dogs, Baermann results were then mostly positive (116/119, 97%) during the patent period, with wide variations in the numbers of first stage larvae numbers. Blood PCR was tested positive on 1-2 occasions in 11/16 dogs in the pre-patent period, while all tested positive by antibody-detection ELISA by 6 wpi. The proportion of dogs testing positive by fecal PCR and antigen-detection ELISA rose early in the patent period. Tracheal swabs were occasionally DNA-positive in 3/16 dogs starting from 10 wpi. Following treatment, larval excretion stopped within 3 weeks and blood PCR results became negative within 1 week (5/6 dogs), while 4/6 dogs were positive for parasite DNA in tracheal swabs. Parasite antigen and specific antibodies both persisted in the blood for 3-9 weeks after treatment, with average optical densities and the proportion of positive dogs falling gradually, while results using other tests were much more variable. Results indicate that the earliest and most consistent results are obtained by the ELISAs, which can also be used for monitoring dogs after anthelmintic treatment.

Epidemiological survey of Angiostrongylus vasorum in dogs and slugs around a new endemic focus in Scotland

The nematode parasite Angiostrongylus vasorum is an increasingly important cause of respiratory and other diseases in dogs. Geographical spread from previously limited endemic foci has occurred rapidly. This paper investigates parasite epidemiology around the location of the first reported case in Scotland in 2009: by detection of A vasorum-specific DNA in gastropod intermediate hosts, and in dogs circulating DNA and specific antibodies, and first stage larvae in faeces. Overall prevalence in gastropods was 6.7 per cent (16/240), with parasite DNA found in slugs in the Arion ater and Arion hortensis species aggregates and the snail Helix aspersa (syn. Cornu aspersum). Of 60 dogs presenting with clinical signs compatible with angiostrongylosis, none tested positive using PCR on peripheral blood or Baermann test on faeces, and none of 35 tested for circulating anti-A vasorum antibodies were positive. PCR prevalence in gastropods was highest (11 per cent) in the park frequented by the canine angiostrongylosis index case. Molecular survey for infection in gastropods is a potentially informative and efficient method for characterising the distribution of A vasorum and therefore local risk of canine infection. However, there appears to be a complex relationship between prevalence in gastropods and emergence of canine clinical disease, which requires further work to advance understanding of parasite transmission and geographical disease spread.

Seroepidemiological survey for canine angiostrongylosis in dogs from Germany and the UK using combined detection of Angiostrongylus vasorum antigen and specific antibodies

Dogs infected with Angiostrongylus vasorum, a potentially lethal parasite parasitizing the heart and pulmonary arteries, may present severe respiratory, haematological and neurological signs. In this first large-scale seroepidemiological survey, 4003 sera originating from Germany and 4030 from the UK were tested by an ELISA for the detection of circulating antigen of A. vasorum, and by a separate ELISA detecting specific antibodies. In Germany, where mainly western federal states were sampled, 0·3% (n = 13, CI: 0·2–0·6%) of dogs were positive in both ELISAs, whereas in total 0·5% (n = 20, CI: 0·3–0·8%) were antigen-positive and 2·25% (n = 90, CI: 1·8–2·8%) were positive for specific antibodies. Regions with antigen- and antibody-positive animals were overlapping. In the UK, where mainly the south of the country was sampled, 0·97% (n = 39, CI: 0·7–1·3%) of dogs were antigen- and antibody positive. In total, 1·32% (n = 53, CI: 1·0–1·7%) were antigen-positive, and 3·2% (n = 129, CI: 2·7–3·8%) were positive for specific antibodies, again in overlapping regions. These results confirm the occurrence of A. vasorum in a random dog population originating from large parts of the countries investigated. The use of the tests alone or in combination was considered as a function of their sensitivities and specificities, in order to guide efficient clinical and epidemiological application.

Canine angiostrongylosis: recent advances in diagnosis, prevention, and treatment

Angiostrongylus vasorum is a parasitic nematode affecting the heart and pulmonary arteries of wild (eg, foxes) and domestic canids. The parasite has an indirect life cycle in which slugs and snails act as intermediate hosts. In the last few years the parasite has spread outside the traditional endemic foci, and there is a rise of documented cases of canine angiostrongylosis across Europe. Angiostrongylus vasorum causes cardiopulmonary disorders and coagulopathies, along with different nonspecific clinical signs. Fatal infections are frequently reported. Given the severity of the infection and the recent geographic spreading of the parasite, this article reviews and discusses the current knowledge of A. vasorum, with a special focus on recent insights on diagnosis, prevention, and treatment of dog angiostrongylosis.

Recent advances in the epidemiology, clinical and diagnostic features, and control of canine cardio-pulmonary angiostrongylosis

The aim of this review is to provide a comprehensive update on the biology, epidemiology, clinical features, diagnosis, treatment, and prevention of canine cardio-pulmonary angiostrongylosis. This cardiopulmonary disease is caused by infection by the metastrongyloid nematode Angiostrongylus vasorum. The parasite has an indirect life cycle that involves at least two different hosts, gastropod molluscs (intermediate host) and canids (definitive host). A. vasorum represents a common and serious problem for dogs in areas of endemicity, and because of the expansion of its geographical boundaries to many areas where it was absent or uncommon; its global burden is escalating. A. vasorum infection in dogs can result in serious disorders with potentially fatal consequences. Diagnosis in the live patient depends on faecal analysis, PCR or blood testing for parasite antigens or anti-parasite antibodies. Identification of parasites in fluids and tissues is rarely possible except post mortem, while diagnostic imaging and clinical examinations do not lead to a definitive diagnosis. Treatment normally requires the administration of anthelmintic drugs, and sometimes supportive therapy for complications resulting from infection.

Molecular identification of novel intermediate host species of Angiostrongylus vasorum in Greater London

Angiostrongylus vasorum is a parasitic nematode that can cause serious and potentially fatal disease in dogs and other canids. The aim of this study was to determine the intermediate slug species infected in nature by sampling sites in Greater London and Hertfordshire located within a known hyperendemic region. Overall, A. vasorum larvae were recovered from 6/381 slugs (1.6%) by tissue digestion, and their identity was confirmed by PCR. Infected slugs originated from three different sites in the Greater London area: one in Waltham Forest and two in Bromley. Slugs parasitised by A. vasorum were identified by a combination of external morphological characteristics and molecular techniques and belonged to three different families: the Arionidae, the Milacidae and the Limacidae. This includes two new host records for the parasite: Arion distinctus and Tandonia sowerbyi. This is the first record of A. vasorum in the family Milacidae, indicating that the parasite has a broader intermediate host range than previously recognised.

Evaluation of a rapid device for serological in-clinic diagnosis of canine angiostrongylosis

Background

Angiostrongylus vasorum is a potentially fatal canine nematode. Due to the high variability of clinical signs and the often chronic and subtle course of the infections, the diagnosis is particularly challenging. A rapid in-clinic assay (Angio Detect™ Test, IDEXX Laboratories, Westbrook, Maine, USA) for the serological detection of circulating antigen and intended for routine in-clinic diagnosis has been evaluated.

Methods

Sensitivity was calculated with sera from 39 naturally infected dogs confirmed by Baermann-Wetzel analysis, while sera of 38 experimentally infected dogs were used for follow-up analyses, of which 10 were treated with imidacloprid/moxidectin. Cross-reactivity was tested with a total of 123 samples from dogs with proven parasitic infections with Toxocara canis (n = 21), Ancylostoma caninum (n = 4), Crenosoma vulpis (n = 18), Oslerus osleri (n = 3), Eucoleus aerophilus, (n = 6), Dirofilaria immitis (n = 28), Dirofilaria repens (n = 20), Acantocheilonema reconditum (n = 10) or Dipetalonema dracunculoides (n = 10) or multiple infections (n = 3). All sera were tested with the Angio Detect™ Test and with an ELISA for detection of circulating antigen of A. vasorum.

Results

The sensitivity of the Angio Detect™ Test was 84.6% (95% C.I. 69.5 - 94.1%), while specificity was 100% (95% C.I. 97.6 - 100%). The sensitivity of the ELISA (94.9%, 95% C.I. 82.7 – 99.3%) was comparable with previous evaluations. In experimentally infected dogs, earliest positive results with the Angio Detect™ Test were observed 9 weeks post inoculation and 5 weeks later all sera were Angio Detect™ Test positive. After anthelmintic treatment, seropositive dogs turned negative again within 3 to 7 weeks after treatment. The evaluation of the colour intensity of the test strips confirmed the delay of approximately 3-4 weeks for antigen detection by the Angio Detect™ Test compared to the ELISA and its correlation with the time after infection.

Conclusions

This study provided evidence of a good sensitivity and a very high specificity of the rapid device Angio Detect™ Test for detection of circulating A. vasorum antigen in dogs with suspected canine angiostrongylosis, representing a very simple and useful tool to be broadly applied in veterinary practices. The rapid detection of infected dogs is a key point for initiating an indispensable and urgent therapy.

Canine angiostrongylosis in naturally infected dogs: clinical approach and monitoring of infection after treatment

Canine angiostrongylosis is an increasingly reported disease in Europe which can be fatal if left untreated. The wide range of clinical presentation along with the absence of pathognomonic alterations can make the diagnosis challenging; thus any additional information that may provide clues to an early diagnosis may be of value, in order to ensure adequate anthelmintic treatment. Aim of the study was to assess a clinicopathological scoring system associated with natural Angiostrongylus vasorum infection diagnosed in canine patients during clinical practice, to clinically and paraclinically monitor infected dogs after treatment, and to monitor the presence of L1 larvae in faecal samples by Baermann's test. Of the total 210 enrolled animals A. vasorum infection was diagnosed in 7 dogs. These dogs were clinically and paraclinically investigated and monitored after specific treatment. Further 3 symptomatic dogs were retrospectively included in the monitoring. Results suggest that the computed scoring system can help to increase the clinical suspicion of infection particularly in asymptomatic dogs before the onset of potentially lethal lesions. Data of faecal monitoring suggested that treatment may control parasite burden but be unable to eradicate infection. Thus, a continued faecal monitoring after treatment is advisable for identification of still infected or reinfected dogs.

Angiostrongylus vasorum in wolves in Italy

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Nematodes found in dead wolves in Rome province, Italy, were confirmed to be Angiostrongylus vasorum.

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Molecular evidence further showed homology with lungworm larvae in sympatric dogs.

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It is not known whether wolves represent ancentral hosts or are subject to more recent spill-over from dogs and foxes.

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The parasite is pathogenic, emerging, and should be borne in mind in wolf conservation programmes in endemic areas.

In the past decade, the parasitic nematode Angiostrongylus vasorum has attracted attention for its emergence in previously free areas and for the rise in clinical cases in domestic dogs. Italy is regarded as one of the countries where this potentially life-threatening parasite is spreading, especially due to bridging infections between wildlife and domestic dogs. The present article describes the presence of A. vasorum in wolves from Italy. Nematodes were observed in histological sections of three wolves found dead in Rome province, central Italy. Morphological and molecular identification of the nematodes, by polymerase chain reaction of rDNA ITS-2 and sequencing, confirmed the nematodes to be A. vasorum, with 99% genetic homology with A. vasorum from sympatric dogs. This is the second report of this species in wolves and the first in this host in Italy, and coincides with increasing records of A. vasorum in dogs and foxes in Italy. Implications for the epidemiology of this emerging parasite and for wildlife health are concisely discussed.

Development and validation of real-time PCR for rapid detection of Mecistocirrus digitatus

Hematophagous activity of Mecistocirrus digitatus, which causes substantial blood and weight loss in large ruminants, is an emerging challenge due to the economic loss it brings to the livestock industry. Infected animals are treated with anthelmintic drugs, based on the identification of helminth species and the severity of infection; however, traditional methods such as microscopic identification and the counting of eggs for diagnosis and determination of level of infection are laborious, cumbersome and unreliable. To facilitate the detection of this parasite, a SYBR green-based real-time PCR was standardized and validated for the detection of M. digitatus infection in cattle and buffaloes. Oligonucleotides were designed to amplify partial Internal Transcribed Spacer (ITS)-1 sequence of M. digitatus. The specificity of the primers was confirmed by non-amplification of DNA extracted from other commonly occurring gastrointestinal nematodes in ruminants. Plasmids were ligated with partial ITS-1 sequence of M. digitatus, serially diluted (hundred fold) and used as standards in the real-time PCR assay. The quantification cycle (Cq) values were plotted against the standard DNA concentration to produce a standard curve. The assay was sensitive enough to detect one plasmid containing the M. digitatus DNA. Clinical application of this assay was validated by testing the DNA extracted from the faeces of naturally infected cattle (n = 40) and buffaloes (n = 25). The results were compared with our standard curve to calculate the quantity of M. digitatus in each faecal sample. The Cq value of the assay depicted a strong linear relationship with faecal DNA content, with a regression coefficient of 0.984 and efficiency of 99%. This assay has noteworthy advantages over the conventional methods of diagnosis because it is more specific, sensitive and reliable.

Cross-reactions of sera from dogs infected with Angiostrongylus vasorum in commercially available Dirofilaria immitis test kits

Background

Dirofilaria immitis and Angiostrongylus vasorum are both important potentially fatal canine nematodes with overlapping endemic areas, especially in Europe. The preadult and adult stages of both species are living in the Arteria pulmonalis and the right heart, and diagnostically detectable circulating parasite antigens have been demonstrated for both species. For the detection of D. immitis infections, a variety of commercial tests have been developed, however, they have not been evaluated for cross-reactions against circulating antigens of A. vasorum.

Methods

In this study, potential cross-reactions of sera from 16 dogs, which were experimentally infected with A. vasorum and which had circulating antigens as confirmed by a species-specific ELISA, were evaluated for the detection of A. vasorum antigen in six commercially available D. immitis test kits.

Results

In three fast tests (Witness® Dirofilaria, SensPERT® Canine Heartworm, SNAP® 4Dx® Plus), all sera were negative. One fast membrane ELISA (SNAP® HTWM RT Test) was positive with four sera (25%), and one serum delivered a non-valid result twice. In the PetChek® HTWM PF Test, depending on the interpretation protocol, 5 or 8 dogs (31.2 – 50%) were positive. With the DiroCHEK®-ELISA, a single A. vasorum-infected dog (6.2%) tested positive.

Conclusions

Due to potential cross-reactions with A. vasorum in commercially available test kits for the detection of D. immitis antigen, the simultaneous use of highly specific diagnostic methods for the differentiation of these two canine heart worms is recommended.

Parasite epidemiology in a changing world: can molecular phylogeography help us tell the wood from the trees?

SUMMARY Molecular phylogeography has revolutionised our ability to infer past biogeographic events from cross-sectional data on current parasite populations. In ecological parasitology, this approach has been used to address fundamental questions concerning host-parasite co-evolution and geographic patterns of spread, and has raised many technical issues and problems of interpretation. For applied parasitologists, the added complexity inherent in adding population genetic structure to perceived parasite distributions can sometimes seem to cloud rather than clarify approaches to control. In this paper, we use case studies firstly to illustrate the potential extent of cryptic diversity in parasite and parasitoid populations, secondly to consider how anthropogenic influences including movement of domestic animals affect the geographic distribution and host associations of parasite genotypes, and thirdly to explore the applied relevance of these processes to parasites of socio-economic importance. The contribution of phylogeographic approaches to deeper understanding of parasite biology in these cases is assessed. Thus, molecular data on the emerging parasites Angiostrongylus vasorum in dogs and wild canids, and the myiasis-causing flies Lucilia spp. in sheep and Cochliomyia hominovorax in humans, lead to clear implications for control efforts to limit global spread. Broader applications of molecular phylogeography to understanding parasite distributions in an era of rapid global change are also discussed.

Twenty two cases of canine neural angiostrongylosis in eastern Australia (2002-2005) and a review of the literature

Cases of canine neural angiostrongylosis (NA) with cerebrospinal fluid (CSF) evaluations in the peer-reviewed literature were tabulated. All cases were from Australia. A retrospective cohort of 59 dogs was contrasted with a series of 22 new cases where NA was diagnosed by the presence of both eosinophilic pleocytosis and anti-Angiostrongylus cantonensis immunloglobulins (IgG) in CSF, determined by ELISA or Western blot. Both cohorts were drawn from south east Queensland and Sydney. The retrospective cohort comprised mostly pups presented for hind limb weakness with hyperaesthesia, a mixture of upper motor neurone (UMN) and lower motor neurone (LMN) signs in the hind limbs and urinary incontinence. Signs were attributed to larval migration through peripheral nerves, nerve roots, spinal cord and brain associated with an ascending eosinophilic meningo-encephomyelitis. The contemporary cohort consisted of a mixture of pups, young adult and mature dogs, with a wider range of signs including (i) paraparesis/proprioceptive ataxia (ii) lumbar and tail base hyperaesthesia, (iii) multi-focal central nervous system dysfunction, or (iv) focal disease with neck pain, cranial neuropathy and altered mentation. Cases were seen throughout the year, most between April and July (inclusive). There was a preponderance of large breeds. Often littermates, or multiple animals from the same kennel, were affected simultaneously or sequentially. A presumptive diagnosis was based on consistent signs, proximity to rats, ingestion/chewing of slugs or snails and eosinophilic pleocytosis. NA was diagnosed by demonstrating anti-A. cantonensis IgG in CSF. Detecting anti-A. cantonensis IgG in serum was unhelpful because many normal dogs (20/21 pound dogs; 8/22 of a hospital population) had such antibodies, often at substantial titres. Most NA cases in the contemporary series (19/22) and many pups (16/38) in the retrospective cohort were managed successfully using high doses of prednisolone and opioids. Treatment often included antibiotics administered in case protozoan encephalomyelitis or translocated bacterial meningitis was present. Supportive measures included bladder care and physiotherapy. Several dogs were left with permanent neural deficits. Dogs are an important sentinel species for NA. Human cases and numerous cases in tawny frogmouths were reported from the same regions as affected dogs over the study period.

Geographical, clinical, clinicopathological and radiographic features of canine angiostrongylosis in Irish dogs: a retrospective study

Background

Angiostrongylus vasorum infection is associated with high morbidity and mortality in dogs. Although recognised in Ireland, there are no large series of cases reported. The aim of this retrospective study was to identify pertinent clinical and geographical features in Irish dogs.

Results

The case records of dogs presenting to the University College Dublin Veterinary Hospital (1999-2010) were reviewed. A contemporaneous review of external faecal parasitology and post mortem submissions was also performed. A positive diagnosis of angiostrogylosis was identified in 49 dogs including 24 clinical, 10 post mortem and 15 external faecal sample cases. The majority (n = 44 (90%)) resided on the East Coast.

In the clinical cases, the median age was 20 months, 29% of cases were older than 2 years. Clinical features included cardiorespiratory (63%), coagulopathic (71%) and other (63%) signs. Cough (n = 10), dyspnoea (n = 5) and tachypnoea (n = 3) were the most common cardiorespiratory abnormalities. Of animals with evidence of coagulopathy, excessive haemorrhage from a wound (n = 5), airway haemorrhage (n = 9), epistaxis (n = 3), haematoma (n = 4), suspected haemarthrosis (n = 3), neurological signs (n = 2) and haematuria (n = 1) were found. Ten dogs were anaemic, of which two were severe (haematocrit ≤ 0.20 L/L). Ten animals had thrombocytopenia, with four severely affected (≤50 × 10⁹/L). PT and APTT values were prolonged in 4 (24%) of 17 and a BMBT was prolonged in 5 (63%) of 8 cases. Vague signs of exercise intolerance (n = 6), lethargy (n = 6) and weakness (n = 2) were identified, with two (8%) animals having only these signs. In one animal the diagnosis appeared to be incidental. Thoracic radiographs (n = 19) identified abnormalities in 100% of cases. Four (17%) animals died before or within 24 hours of treatment and post mortem examinations confirmed angiostrongylosis. Fenbendazole was administered in 19 cases, 18 (95%) recovered. Two animals were euthanised, one which failed to respond to therapy and another in which an ante mortem diagnosis had not been made.

Conclusions

Angiostrongylosis is not uncommon in Ireland, is not confined to young dogs or the East Coast and can present with a wide variety of signs, particularly coagulopathic, respiratory or neurological signs.