Leishmaniosis in a dog with no travel history outside of the UK

Global Distribution of Canine Visceral Leishmaniasis and the Role of the Dog in the Epidemiology of the Disease

Visceral leishmaniasis is a disease caused by protozoa of the species Leishmania (Leishmania) infantum (syn = Leishmania chagasi) and Leishmania (Leishmania) donovani, which are transmitted by hematophagous insects of the genera Lutzomyia and Phlebotomus. The domestic dog (Canis familiaris) is considered the main urban reservoir of the parasite due to the high parasite load on its skin, serving as a source of infection for sandfly vectors and, consequently, perpetuating the disease in the urban environment. Some factors are considered important in the perpetuation and spread of canine visceral leishmaniasis (CVL) in urban areas, such as stray dogs, with their errant behavior, and houses that have backyards with trees, shade, and organic materials, creating an attractive environment for sandfly vectors. CVL is found in approximately 50 countries, with the number of infected dogs reaching millions. However, due to the difficulty of controlling and diagnosing the disease, the number of infected animals could be even greater. In the four continents endemic for CVL, there are reports of disease expansion in endemic countries such as Brazil, Italy, Morocco, and Tunisia, as well as in areas where CVL is not endemic, for example, Uruguay. Socio-environmental factors, such as migration, drought, deforestation, and global warming, have been pointed out as reasons for the expansion into areas where it had been absent. Thus, the objective of this review is to address (i) the distribution of CVL in endemic areas, (ii) the role of the dog in the visceral leishmaniasis epidemiology and the factors that influence dog infection and the spread of the disease, and (iii) the challenges faced in the control of CVL.

Analysis of exotic pathogens found in a large group of imported dogs following an animal welfare investigation

BACKGROUND

Increased dog relocation can cause dissemination of pathogen and vector populations, and this is being recognised in countries across Northern Europe, including the UK. Data regarding the prevalence of exotic infections in dogs entering the UK would be beneficial to veterinarians to help assess pets entering the UK from abroad and to help calculate the risk of establishment of novel pathogens. This study reports the findings from a group of imported dogs that was seized as part of a Royal Society for the Prevention of Cruelty to Animals (RSPCA)-led animal welfare investigation and subsequently blood tested for exotic pathogens.

METHODS

As part of the RSPCA investigation, 151 dogs were removed from the site. Blood tests were performed for Babesia canis, Ehrlichia canis, Hepatozoon canis and Leishmania infantum by PCR, Brucella canis by antibody serology and Dirofilaria immitis by blood antigen. In addition to pathogen screening, a serology titre for rabies was measured for each dog. A clinical examination was performed by a veterinary surgeon, and clinical signs were recorded.

RESULTS

Overall, 24% (32/133) of the dogs tested positive for an infection with one or more exotic pathogens. Two dogs were positive for Br. canis antibodies and had no clinical signs indicative of infection. Leishmania was identified in 10.5% (14/133) of dogs, and all but two of these were implanted with microchips of Romanian origin. H. canis was identified in 9.6% (10/104) of dogs, all of whom had a Romanian microchip. D. immitis was identified in 4.1% (5/121) of dogs, B. canis in 2.3% (3/129) of dogs and E. canis in only 1.5% (2/131) of dogs tested. Only four dogs were found to have co-infections. No significant association was found between the pathogens detected and presenting clinical signs.

LIMITATIONS

This was a group of rescued dogs that were tested for a range of pathogens. They were not randomly selected and as such do not represent the true prevalence of these pathogens in dogs imported into the UK.

CONCLUSIONS

This study demonstrates a range of exotic pathogens entering the UK, including Br. canis, and demonstrates the importance of screening imported dogs. The emphasis on early recognition of exotic pathogens in imported dogs has relied on screening based on relevant clinical signs and the country of origin. While these factors are useful, this study demonstrated no significant association between presenting clinical signs and the pathogens carried.

Spurious laboratory results associated with immunoglobulin M gammopathy in a dog with multiple myeloma

An 11 year old female-neutered Labrador presented for facial swelling. Clinicopathological abnormalities included hyperglobulinemia, azotemia, hypercalcemia, nonregenerative anemia, thrombocytopenia, and spurious hypoglycemia. Normoglycemia was subsequently confirmed using a cage-side analyzer (AlphaTRAK, Zoetis, UK). Serum and urine protein electrophoresis documented monoclonal (immunoglobulin M) gammopathy with Bence-Jones proteinuria. Computed tomography imaging revealed a monostotic osteolytic bone-lesion, and bone marrow cytology and histopathology documented plasmacytosis with multiple myeloma oncogene 1 / interferon regulatory factor 4 positivity, consistent with multiple myeloma. Infectious disease testing initially indicated seropositivity for Leishmania, Borrelia, and Anaplasma spp.; however, Leishmania PCR (splenic and bone marrow aspirates), and paired serological titers for Borrelia and Anaplasma were negative. Consequently, initial serological results were considered to be false positive because of paraproteinemia-associated assay interference. Chemotherapy (prednisolone and melphalan combination therapy) was initiated, but the dog was euthanased 30 days later because of the development of pericardial effusion. This is a report of spurious serological (and other laboratory) results occurring secondary to monoclonal gammopathy in a dog.

Canine Leishmaniasis: Update on Epidemiology, Diagnosis, Treatment, and Prevention

Dog are the main reservoir of Leishmania infantum, causing canine leishmaniasis, an incurable multisystemic disease that leads to death in symptomatic dogs, when not treated. This parasite causes visceral, cutaneous, and mucosal leishmaniasis in people in the Mediterranean Basin, North Africa, South America, and West Asia. This disease is mostly unknown by veterinarians outside the endemic areas, but the disease is expanding in the Northern Hemisphere due to travel and climate change. New methodologies to study the epidemiology of the disease have found new hosts of leishmaniasis and drawn a completely new picture of the parasite biological cycle. Canine leishmaniasis diagnosis has evolved over the years through the analysis of new samples using novel molecular techniques. Given the neglected nature of leishmaniasis, progress in drug discovery is slow, and the few drugs that reach clinical stages in humans are unlikely to be commercialised for dogs, but several approaches have been developed to support chemotherapy. New-generation vaccines developed during the last decade are now widely used, along with novel prevention strategies. The implications of the epidemiology, diagnosis, treatment, and prevention of canine leishmaniasis are fundamental to public health.

Linguatula serrata in an imported dog in Germany: Single-case or emerging disease?

Linguatula serrata is a worm-like parasite with zoonotic potential that inhabits the nasal cavities of canids. Although most cases of linguatulosis are associated with unspecific and rather mild respiratory symptoms, cases of unusual infestations and severe courses in both animals and humans have been reported. In central and northern Europe, the pathogen used to appear only sporadically, however, within the last few years the number of detections has increased noticeably. In July 2020 an approximately nine-month-old dog, imported from Romania, was presented in a veterinary practice in Gotha, central Germany, due to persistent worsening cough. Despite antibiotic treatment the tussis became more severe until the dog expectorated multiple worm-like structures. Three of these specimens were sent to the Institute of Parasitology (Faculty of Veterinary Medicine, University of Leipzig, Leipzig) for morphological and genetic species identification. The latter was based on a 1000-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (cox1) and the complete nuclear 18S rRNA gene. The dog presented in this study suffered from a severe respiratory impairment caused by worm-like parasites inhabiting its upper respiratory tract. The detected parasites were morphologically identified as female specimens of the so-called tongue-worm L. serrata, which was confirmed by pairwise alignment and phylogenetic analysis of the produced sequences. We report an unusually severe case of L. serrata infection in an imported dog and discuss the spread of this potentially dangerous parasite in central and northern Europe.

Temporospatial distribution and country of origin of canine transmissible venereal tumours in the UK

OBJECTIVE

Transmissable venereal tumour (TVT) is a tumour transplanted by physical contact between dogs. Lesions typically affect the genitalia. TVT is not considered enzootic in the United Kingdom (UK), with cases seen in imported dogs. We sought to determine the patient characteristics, temporal and spatial distribution and country of origin of affected dogs in the UK.

METHODS

Electronic pathology records (EPRs) from four UK veterinary diagnostic laboratories collected between 2010 and 2019 were searched for the terms 'venereal' or 'TVT'. Reports were reviewed for statements confirming a TVT and descriptive statistics collated.

RESULTS

Of 182 EPRs matching the search terms, a diagnosis of TVT was confirmed in 71. Country of origin was noted in 36 cases (50.7%) with Romania being the most common (n = 29). Cases were reported in each UK constituent country, with the majority being in England (64, 90.1%). The incidence of TVT diagnosis increased over the last decade (z = 2.78, p = 0.005).

CONCLUSIONS/DISCUSSION

The incidence of TVT diagnosed in the UK is increasing. The majority of cases were known to have been imported. Autochthonous transmission cannot be excluded due to study design. Vets are encouraged to carefully examine the genitalia of dogs imported to the UK from countries with enzootic TVT.

Emergent canine visceral leishmaniasis in Argentina: Comparative diagnostics and relevance to proliferation of human disease

BACKGROUND

Visceral leishmaniasis (VL) is a zoonotic protozoal vector-borne disease that is a major public health challenge. In Argentina, canine (CVL) and human visceral leishmaniasis (HVL) have recently emerged. There is a lack of standardised diagnostic tests for CVL, which hinders control of CVL and HVL.

METHODOLOGY/PRINCIPAL FINDINGS

Sampling was carried out in Puerto Iguazú, Argentina, comprising 190 asymptomatic, oligosymptomatic and polysymptomatic dogs. The following diagnostics were applied: microscopy of lymph node aspirate (LNA); three immunochromatographic rapid diagnostic tests (RDTs), prototype rK28-ICT, rK39-ICT (both Coris BioConcept), commercial rK39 (InBios); ELISA for IgG, IgG1 and IgG2, against rK28, rK39 or crude lysate antigen. DNA detection and analysis, with 30 dogs, was of the ITS1 region using skin samples, and loop-mediated isothermal amplification (LAMP; Eiken Loopamp) of buffy coat, skin scrape or LNA. 15.4% of dogs were positive by LNA microscopy. The rK28 RDT had higher seropositivity rate (61%) than either a prototype rK39 RDT (31.4%) or commercial rK39 RDT (18.8%), without cross-reactivity with six other pathogens. IgG anti-rK39 ELISA antibody titres, but not IgG2, were positively correlated with number of clinical signs. LAMP with LNA had a higher positivity rate than PCR; buffy coat sampling was more sensitive than skin scrape. ITS1 confirmed Leishmania (Leishmania) infantum as the agent of CVL. Leishmania (Viannia) spp. was detected in skin samples from two dogs, compatible with Leishmania (Viannia) braziliensis.

CONCLUSIONS/SIGNIFICANCE

Seroprevalence confirmed rapid increase in CVL in Puerto Iguazú. The rK28 RDT test potentially has great value for improved point-of-care diagnosis. Given cost reduction and accessibility, commercial LAMP may be applicable to buffy coat. RDT biomarkers of CVL clinical status are required to combat spread of CVL and HVL. The presence of Viannia, perhaps as an agent of human mucocutaneous leishmaniasis (MCL), highlights the need for vigilance and surveillance.

Parasites and vector-borne diseases disseminated by rehomed dogs

The Companion Vector-Borne Diseases (CVBD) World Forum is a working group of leading international experts who meet annually to evaluate current scientific findings and future trends concerning the distribution, pathogenesis, clinical presentation, diagnosis and prevention of vector-borne infections of dogs and cats. At the 14th Symposium of the CVBD World Forum in Trieste, Italy (March 25-28, 2019), we identified the need to (i) bring attention to the potential spread of parasites and vectors with relocated dogs, and (ii) provide advice to the veterinary profession regarding the importance of surveillance and treatment for parasites and vector-borne infections when rehoming dogs. This letter shares a consensus statement from the CVBD World Forum as well as a summary of the problem faced, including the role of veterinary professionals in parasite surveillance, causal issues, and the importance of interdisciplinary cooperation in addressing the problem. To limit opportunities for dissemination of parasites and vectors, whenever possible, underlying problems creating the need for dog rehoming should be addressed. However, when it is necessary to rehome dogs, this should ideally take place in the country and national region of origin. When geographically distant relocation occurs, veterinary professionals have a vital role to play in public education, vigilance for detection of exotic vectors and infections, and alerting the medical community to the risk(s) for pathogen spread. With appropriate veterinary intervention, dog welfare needs can be met without inadvertently allowing global spread of parasites and their vectors.

Importation of cats and risk of parasite spread: a Caribbean perspective and case study from St Kitts

BACKGROUND

In more recent years, international travel with cats has increased. The distribution of cat parasites can change with this movement. Already, subtropical and tropical parasites have been reported by veterinarians in areas where they are not naturally present. Understanding the prevalence of tropical and subtropical parasites in Caribbean islands and the risk of importation to temperate areas could enable improved prevention recommendations and border control import requirements.

METHODS

We present a study focused on cat owning students enrolled in a Doctor of Veterinary Medicine (DVM) programme on St Kitts. Owners were interviewed about their cats and their use of parasiticides. Cats were examined for Trichuris felis and Platynosomum fastosum using sugar flotation, Lynxacarus radovskyi using an adhesive tape test, and Dirofilaria immitis using commercial antigen and antibody tests.

RESULTS

Data on 115 cats owned by 87 DVM students were collected and 90 cats, all expected to travel to the USA, were examined. Most of the cats were adults and born in St Kitts. Prevalence was reported as 6.8% (95% confidence interval (CI): 2.2-15.1%) for T. felis, 16.2% (95% CI: 8.7-26.6%) for P. fastosum and 6.8% (95% CI: 2.5-14.3%) for L. radovskyi. All D. immitis tests were negative. DVM students reported a high level of deworming (83.3% of the cats), but the number of cats treated per recommendations were low (56.1% for endoparasites and 70.8% for ectoparasites). Also, there was a lack of clarity regarding the purpose of the treatments used and treatments did not appear to be targeted for the parasites present.

CONCLUSION

Our results indicate a low prevalence of the parasites of interest in the DVM student cat population compared to other prevalence studies from the Caribbean. However, a degree of non-compliance with parasiticide uses and the high number of cats traveling to the USA indicate a medium risk of importation of tropical and subtropical cat parasites to temperate areas. We recommend stronger health inspections and health screening requirements at the borders including the development of specific parasiticide protocols for cat importation.

Importing rescue dogs into the UK: reasons, methods and welfare considerations

BACKGROUND

Rescuing dogs from overseas is increasing in popularity but has associated risks. This study is the first to investigate the reasons why people bring rescue dogs into the UK from overseas, the importation process, and potential welfare problems associated with this practice.

METHODS

An online questionnaire was advertised on social media in 2017 and received 3080 responses.

RESULTS

Participants primarily chose to adopt from abroad based on a desire for a particular dog they had seen advertised and on concern for its situation. However, some were motivated by previously having been refused dogs from UK rescues. Adopters reported that the EU Pet Travel Scheme was used to import 89 per cent of dogs, with only 1.2 per cent reportedly under the more stringent (and correct) Balai Directive. 14.8 per cent (79/533) of dogs reportedly tested for Leishmania infantum had positive results. Although sometimes severe, the prevalence of behavioural problems appeared comparable to that of other rescue dogs.

CONCLUSION

It is important that vets consider testing for exotic diseases, and the provision of behavioural support, when seeing imported patients. Our findings emphasise the importance of clear guidelines on travel laws, and stricter checks on animals imported as rescues, to ensure protection against the importation of diseases that pose a risk to animal and human health in the UK.

Clonality testing in the lymph nodes from dogs with lymphadenomegaly due to Leishmania infantum infection

INTRODUCTION

In southern European countries, multicentric lymphoma and leishmaniosis are the main differential diagnoses in dogs presented with generalized lymphadenomegaly. The cytological examination is in some cases inconclusive and polymerase chain reaction (PCR) for antigen receptor rearrangement (PARR) has become a common method to confirm or rule out a lymphoproliferative neoplasia. According to the literature, leishmaniosis may lead to clonal arrangements and therefore to a false diagnosis of lymphoma, but this assumption is made from a single leishmania infected dog. Therefore, the objective of this study was to prospectively evaluate results from PARR in dogs with lymphadenomegaly due to clinical leishmaniosis at the moment of diagnosis.

MATERIALS AND METHODS

31 dogs with a diagnosis of leishmaniosis based on the LeishVet guidelines were included in the study. Samples from enlarged lymph nodes were taken for cytological examination, clonality testing and Leishmania infantum PCR.

RESULTS

All 31 dogs had medium to high positive antibody titers against Leishmania spp. and 30/31 had a positive Leishmania PCR from the lymph node. A polyclonal arrangement for B cells (immunoglobulin heavy chain gene) and T cells (T-cell receptor gamma chain gene) antigen receptors was found in 28/31 dogs. Two out of 31 dogs showed a monoclonal arrangement for Ig with high (1:2) and low (1:7) polyclonal background respectively; and one of the 31 dogs showed a monoclonal arrangement for T cell receptor with low (1:3) polyclonal background.

CONCLUSION

Infections with Leishmania infantum resulted in clonal rearrangement, and therefore in a possible false diagnosis of lymphoma, in 3 out of 31 dogs (9.7%). Although, PARR is a useful method to differentiate lymphoma from reactive lymphoid hyperplasia in dogs with leishmaniosis, mono-/biclonal results should be interpreted carefully, especially in the presence of any degree of polyclonal background, and together with other clinicopathological findings.