Emerging risk of Dirofilaria spp. infection in Northeastern Europe: high prevalence of Dirofilaria repens in sled dog kennels from the Baltic countries

Canine Vector-Borne Diseases (CVBDs) in Liguria, North-West Italy: A Retrospective Study over an 11-Year Period (2013-2023)

Canine vector-borne diseases (CVBDs) pose a global threat to both canine and public health. This study evaluates the prevalence of Anaplasma spp., Ehrlichia spp., Borrelia burgdorferi sensu lato (s.l.), Rickettsia conorii, and Dirofilaria immitis in domestic dogs in Liguria, north-west Italy, a region where data were lacking. From 2013 to 2023, 8584 blood samples from shelter (74%) and owned dogs (26%) were submitted to the Istituto Zooprofilattico Sperimentale of Piemonte, Liguria and Valle d'Aosta (IZSPLV) for serological testing (indirect immunofluorescence and/or rapid immunochromatographic tests). Overall, 18.8% (95% CI: 18.0-19.7) of the dogs tested positive for at least one pathogen, with positivity against R. conorii antigen being the most frequently recorded (24.4%, 95% CI: 23.3-25.5). Lower prevalence levels were observed for Anaplasma spp. (1.82%, 95% CI: 1.47-2.23), Ehrlichia spp., (1.25%, 95% CI: 0.97-1.60), B. burgdorferi s.l. (0.22%, 95% CI: 0.11-0.39), and D. immitis (0.84%, 95% CI: 0.65-1.06). Positive cases for all pathogens increased over time, with prevalence differing significantly between owned and shelter dogs. Topographical factors, land use, and monthly relative humidity appeared to influence the positivity in the dogs. These results update the epidemiology of the investigated CVBDs in Liguria, indicating a widespread exposure to Rickettsia spp. among local dogs.

Lesion on the right testicle of 21-year-old patient

Human dirofilariasis is an emerging disease that is rising and driven by increasing travel of both humans and their companion animals and climate change. We report a case of Dirofilaria repens in the scrotum of a 21-year-old patient, who experienced right testicular pain. Ultrasonography revealed a tubular, worm-like lesion extracted successfully and confirmed as an immature D. repens through parasitological and molecular analyses. Post-surgery, the patient underwent anthelmintic treatment and was discharged. Increased awareness of this parasitosis among healthcare professionals is crucial, given the expected rise in dirofilariasis cases. Climate change in Poland, characterized not so much by record high temperatures but by a systematic increase in the number of warm days, affects many aspects of life. Due to the presence of disease vectors, the introduction and reintroduction of exotic and parasitic disease, previously rare or absent in temperate climate zones, is possible.

Detection of Dirofilaria immitis in golden jackals (Canis aureus L.) but not in red foxes (Vulpes vulpes L.) and European badgers (Meles meles L.) in Croatia

BACKGROUND

Dirofilariosis is a parasitic mosquito-borne disease caused by members of the genus Dirofilaria, which includes Dirofilaria immitis and Dirofilaria repens. Surveillance studies in Europe have revealed that D. immitis can also be detected in a range of wild carnivores, raising questions over the impact of infections on wild carnivore animal health but also whether these populations may act as a reservoir for infection of other species, including domestic dogs and humans.

METHODS

In the current study, we conducted surveillance for the presence of D. immitis in several wild carnivore species, including golden jackals (Canis aureus; n = 77), red foxes (Vulpes vulpes; n = 326), and European badgers (Meles meles; n = 28), collected during an annual rabies surveillance and control program from across continental and coastal regions of Croatia.

RESULTS

Macroscopic examination of the right chambers of the heart during a post-mortem examination resulted in the detection of filarial parasites in 6.5% (5/77) golden jackal carcasses. Morphological identification, confirmed by molecular screening, classified all parasites as D. immitis. No D. immitis were detected in the red foxes or European badgers examined. All infected golden jackals were adults aged from 2 to 7 years with a parasite load ranging from 2 to 7 nematodes per carcass. One animal was infected with a sexually mature pair, while a second harbored pre-mature parasites; the remaining positive jackals were infected with female parasites only. Notably, histological examination of cardiac and lung tissue revealed proliferative endarteritis in the jackal with the highest parasite burden.

CONCLUSIONS

Further studies are required to establish whether golden jackals, as well as other wild carnivore hosts, may serve as competent definitive hosts of D. immitis and act as reservoirs for infection of other species including domestic dogs and humans. Histological changes in the cardiac tissue of at least one positive jackal were suggestive of infection with pathological consequences for the host.

Evolution of dirofilariasis diagnostic techniques from traditional morphological analysis to molecular-based techniques: a comprehensive review

Dirofilariasis, caused by the nematode Dirofilaria spp., poses significant challenges in diagnosis due to its diverse clinical manifestations and complex life cycle. This comprehensive literature review focuses on the evolution of diagnostic methodologies, spanning from traditional morphological analyses to modern emerging techniques in the context of dirofilariasis diagnosis. The review traces the historical progression of diagnostic modalities, encompassing traditional approaches such as microscopic examination, serological tests (including ELISA and IFA), radiographic imaging, ultrasonography, and necropsy, which laid the foundation for subsequent advancements. The integration of molecular diagnostics marks a significant turning point in dirofilariasis diagnosis with the adoption of polymerase chain reaction (PCR) assays and real-time PCR (qPCR) facilitating enhanced sensitivity and specificity. Furthermore, recent strides in next-generation sequencing (NGS) technologies, including whole-genome sequencing (WGS), targeted sequencing (TS), metagenomic sequencing (MS), and RNA sequencing (transcriptome sequencing), have revolutionized the landscape of dirofilariasis diagnostics. Emerging techniques such as loop-mediated isothermal amplification (LAMP), digital PCR (dPCR), and digital microfluidics are also explored for their potential to augment diagnostic accuracy. The review addresses challenges associated with standardizing molecular protocols, tackling false positives/negatives, and discusses the advantages and limitations of each technique. By providing a comprehensive overview of dirofilariasis diagnostic strategies, from traditional to cutting-edge methods, this review aims to enhance understanding of the disease's diagnostic landscape. The insights gained have implications for improved disease management and guide future research endeavors toward refining diagnostic protocols and advancing therapeutic interventions.

Dirofilariasis in Male Genitalia: A Case Report and Literature Review

Human dirofilariasis is a rare anthropo-zoonotic disease, mainly detected in Southern and Eastern Europe, Asia Minor, Central Asia, and Sri Lanka. An increasing number of autochthonous Dirofilaria spp. infections has been recently reported in the areas previously considered free of the disease, including northern Europe and the Baltic States. A rare autochthonous case of scrotal dirofilariasis detected in Lithuania was described. Here, a 42-year-old male presented with a 1 cm nodule, limited in the scrotum. A nodule excision was performed. On histological examination, a degenerating roundworm with the features of Dirofilaria spp. (multilayered cuticle, well-developed musculature, focally preserved longitudinal ridges) was detected in the abscess cavity. No additional treatment was needed. Twenty-four publications reporting 28 male genitalia dirofilariasis cases in European countries have been identified.

Zoonotic dirofilariases: one, no one, or more than one parasite

Dirofilaria spp. are vector-borne filarial nematodes that affect a variety of animal species, including humans. Dirofilaria immitis and Dirofilaria repens are the two main zoonotic species, but also other wildlife-associated Dirofilaria species are occasionally reported as causative agents of human dirofilariasis, including Dirofilaria striata, Dirofilaria tenuis, Dirofilaria ursi, Dirofilaria spectans, and Dirofilaria magnilarvata. Since the etiological identity of most of the species mentioned here is arguable, we summarized and critically discussed data concerning infections in humans, focusing on the reliability of Dirofilaria species identification. We advocate the importance of combined morphological and genomic approaches to provide unequivocal evidence for their zoonotic potential and pathogenicity.

An unexpected case of a dog from Poland co-infected with Dirofilaria repens and Dirofilaria Immitis

BACKGROUND

Dirofilariasis is a vector-borne disease caused by parasitic nematodes of the genus Dirofilaria spp., considered an emerging concern in both veterinary and human medicine. Climate changes and human activities, such as pet travel, contribute to the spread of diseases to new non-endemic regions. Poland is dominated by subcutaneous dirofilariasis caused by D. repens infections. Cardiopulmonary dirofilariasis, also known as a heartworm disease is much more rare with only single autochthonous cases reported so far. Also, imported infections are observed sporadically in dogs traveling to endemic countries. In this study, we report the first case of a dog in Poland, never having traveled abroad, co-infected with Dirofilaria repens and Dirofilaria immitis.

CASE PRESENTATION

A 14-year-old mixed breed, an intact male dog with fever, lightly pale mucosal membranes, moderate abdominal pain, and a mild cough was presented in a veterinary clinic in Warsaw, Poland. The examination of the blood sample collected for complete morphology and biochemistry revealed the presence of live microfilariae. Presence of the DNA of both microfilariae species was detected using Real-Time PCR with species-specific primers.

CONCLUSIONS

Since the remaining diagnostic methods like Knott's test, antigen test or echocardiography did not reveal the presence of D. immitis, we discussed the impact of microfilariae periodicity and low worm burden infections on the limited efficiency of these techniques. We strongly recommend using a mixed diagnostic approach for the most sensitive and specific diagnosis since the ideal diagnostic method does not exist, and several factors may contribute to misdiagnosis. Furthermore, we considered factors that contribute to the uncontrolled spread of dirofilariasis such as climate changes, introduction of new species of mosquitoes competent for the transmission of the disease, and wildlife animals as an important reservoir of this parasitosis. Given that Poland shares borders with countries classified as endemic and pre-endemic for D. immitis, such as Slovakia and Ukraine, it is reasonable to anticipate a rise in autochthonous heartworm infections and shifts in the epidemiological pattern of dirofilariasis in the coming years.

Genetic variability of Dirofilaria repens isolates from humans and dogs in Italy

Dirofilaria repens is a paradigmatic example of an emerging vector-borne pathogen (VBP) in both human and veterinary fields. The spatial expansion and the increasing zoonotic impact of this VBP can be related to several drivers including the genetic structure of parasite populations. Italy is one of the European countries traditionally endemic with the highest incidence of canine and human cases of subcutaneous dirofilariosis. The present study aimed to assess the genetic identity and variability of D. repens isolates of human and canine origin from areas of Central Italy, compared with those isolated from different areas of Europe by sequence analysis of mtDNA genes (i.e., 12 S rDNA and cox1). A total of twenty isolates of D. repens were obtained from biopsies of subcutaneous and ocular cases of dirofilariosis occurring in 10 dogs and 10 humans. The sequence analysis of 12 S rDNA showed that all the sequences obtained clustered as a monophyletic group with a strong nodal support, indicating that all sequence types represented D. repens. The cox1 and the 12 S sequence analysis did not show host-related polymorphisms between human and dog-derived specimens. The sequence analysis of cox1 was performed including 8 additional sequences previously obtained from human and canine isolates in the same areas. Out of the 28 sequences analyzed, 20 were grouped in a haplogroup comprising 15 haplotypes (i.e., DR1, DR2, DR4, DR5, DR7, DR8, DR10-DR18), 2 sequences matched to DR9, reported for the first time in Italy, and 6 showed peculiar polymorphisms that were not previously described. The results obtained have implications for a better understanding of the epidemiology and phylogeography of this emerging vector-borne zoonotic parasite.

Vector-borne parasites in dogs from Ukraine translocated to Poland following Russian invasion in 2022

INTRODUCTION

Since 24 February 2022, the day the Russian aggression against Ukraine began, millions of refugees and thousands of pets crossed the Polish-Ukrainian border. Additionally, an unknown number of shelter and stray dogs and cats were rescued and translocated to Poland by private persons and non-profit organizations. The aim of the present study was to examine rescued dogs and cats for presence of canine vector-borne parasites to determine the role of armed conflict in spreading these parasites.

METHODS

In July 2022 blood samples were collected from two animal shelters in central Poland hosting dogs and cats rescued from Ukraine. Animals were imported from various regions of Ukraine, including eastern and southeastern Ukraine (military conflict area). Fifty-three dogs (51 from two shelters and two owned ones) and one shelter cat were examined by molecular methods (PCR and sequencing) for the presence of Babesia/Theileria spp., Dirofilaria spp. and Hepatozoon spp. DNA.

RESULTS

We detected Dirofilaria immitis, a parasite species non-endemic in Poland, in two dogs translocated from Ukraine (2/53 = 3.8% [95% CI 0.5-13.0%]). One dog had a history of previous heartworm infection. High prevalence of Hepatozoon canis (51% [95% CI 36.8-64.9%]) was noted among translocated dogs. Prevalence of Dirofilaria repens in Ukrainian dogs (18.9% [95% CI 9.4-32.0%) was similar to prevalence in dogs from central Poland (12%). Co-infection of D. repens and D. immitis was found in two dogs and six dogs were co-infected by D. repens and H. canis. Hepatozoon canis infection was also identified in an imported cat.

CONCLUSION

We confirmed that this military conflict has facilitated the spread of canine vector-borne parasites, including zoonotic species.

Diversity and geographic distribution of haplotypes of Dirofilaria immitis across European endemic countries

BACKGROUND

Dirofilaria immitis, also known as heartworm, is one of the most important parasitic nematodes of domestic dogs, causing a potentially serious disease, cardiopulmonary dirofilariosis, which can be lethal. This species seems to be less 'expansive' than its sister species Dirofilaria repens, and it is believed that climate change facilitates the spread of this parasite to new non-endemic regions.

METHODS

In total, 122 heartworm isolates were analysed from nine endemic countries in Europe (Portugal, Spain, Italy, Greece, Hungary, Romania, Slovakia, and Ukraine) and a single isolate from Bangladesh by amplification and sequencing of two mitochondrial (mt) DNA markers: cytochrome c oxidase subunit 1 (COI) and dehydrogenase subunit 1 (NADH). The main aim of the current study was to determine the genetic diversity of D. immitis and compare it with D. repens haplotype diversity and distribution. DNA was extracted from adult heartworms or microfilariae in blood. Most isolates originated from dogs (Canis lupus familiaris) while 10 isolates originated from wildlife species from Romania, including eight isolates from golden jackals (Canis aureus), one isolate from a Eurasian otter (Lutra lutra) and one isolate from a red fox (Vulpes vulpes).

RESULTS

Median spanning network analysis was based on the combined sequence (1721 bp) obtained from two mt markers and successfully delineated nine haplotypes (Di1-Di9). Haplotype Di1 was the dominant haplotype encompassing 91 out of the 122 sequences (75%) from all nine countries and four host species. Haplotype Di2 was the second most common haplotype, formed solely by 13 isolates from Italy. The remaining sequences were assigned to Di3-Di9 haplotypes, differing by 1-4 SNPs from the dominant Di1 haplotype. There was evidence for geographical segregation of haplotypes, with three unique haplotypes associated with Italy and four others associated with certain countries (Di4 and Di7 with Slovakia; Di8 with Greece; Di6 with Hungary).

CONCLUSION

Diversity in D. immitis mt haplotypes was lower by half than in D. repens (9 vs. 18 haplotypes in D. immitis and D. repens, respectively), which may be associated with the slower expansion of heartworm in Central and NE Europe. NADH gene appears to be conserved in Dirofilaria sp. by showing lower genetic diversity than the analysed COI gene.

Dirofilaria repens in a dog imported to Denmark: A potential for emerging zoonotic disease

Dirofilarosis is spreading among dogs and humans in Europe with infections being established in many countries. Here, we describe the first molecular biologically confirmed case of D. repens infection in an imported dog in Denmark and highlight the potential zoonotic aspects from this emerging zoonotic parasite in central and northern Europe as at least one to two generations of Dirofilaria spp. can occur per year in Denmark.

Albuminuria and proteinuria in dogs infected with Dirofilaria repens: A cross-sectional study

BACKGROUND

It is unknown whether Dirofilaria repens is capable of causing similar glomerular lesions, as does Dirofilaria immitis.

OBJECTIVE

To determine whether D. repens infection could cause albuminuria or proteinuria.

ANIMALS

Sixty-five clinically healthy laboratory beagle dogs.

METHODS

In this cross-sectional study, dogs were tested for D. repens infection (modified Knott test, PCR test, D. immitis antigen test) and were grouped as "D. repens infected" or "control" dogs. Urinary albumin-to-creatinine ratio (UAC) and urinary protein-to-creatinine ratio (UPC) were measured from samples taken by cystocentesis.

RESULTS

Forty-three (26 infected, 17 control) dogs were included in the final study group. UAC but not UPC level was significantly higher in the infected group (UAC median 12.5; range, 0-700 mg/g and UPC median 0.15; range, 0.06-1.06) than in the control group (UAC median 6.3; range, 0-28 mg/g and UPC median 0.13; range, 0.05-0.64; P = .02 and P = .65). Overt proteinuria (UPC > 0.5) was present in 6/26 (23%) of the infected dogs and 1/17 (6%) of the control dogs. Albuminuria (UAC > 19 mg/g) was detected in 9/26 (35%) dogs in the infected group, and 2/17 dogs (12%) in the control group.

CONCLUSIONS AND CLINICAL IMPORTANCE

D. repens might cause similar glomerular lesions to those caused by D. immitis.

Occurrence of Dirofilaria repens in wild carnivores in Poland

Dirofilaria repens is an expanding vector-borne zoonotic parasite of canines and other carnivores. Sub-clinically infected dogs constitute the most important reservoir of the parasite and the source of infection for its mosquito vectors. However, occurrence of D. repens infection in wild animals may contribute to the transmission of the parasite to humans and may explain the endemicity of filariae in newly invaded regions. The aim of the current study was to determine the occurrence of D. repens in 511 blood and spleen samples from seven species of wild carnivores (wolves, red foxes, Eurasian badgers, raccoons, raccoon dogs, stone martens, and pine martens) from different regions of Poland by means of a PCR protocol targeting the 12S rDNA gene. Dirofilaria repens-positive hosts were identified in seven of fourteen voivodeships in four of the seven regions of Poland: Masovia, Lesser Poland, Pomerania and Warmia-Masuria. The highest prevalence was found in Masovia region (8%), coinciding with the highest previously recorded prevalence in dogs in Central Poland. The DNA of Dirofilaria was detected in 16 samples of three species (total prevalence 3.13%). A low and similar percentage of positive samples (1.9%, 4.2% and 4.8%) was recorded among badgers, red foxes, and wolves, respectively. Dirofilaria repens-positive hosts were identified in seven of fourteen voivodships. Based on detection in different voivodeships, D. repens-positive animals were recorded in four out of the seven regions of Poland: in Masovia, Lesser Poland, Pomerania, and Warmia-Masuria. The highest prevalence of filariae was found in Masovia region (8%), reflecting the highest previously recorded prevalence in dogs (12-50%) in Central Poland. In summary, we conducted the first comprehensive study on the epidemiology of D. repens in seven species of wild hosts in all seven regions of Poland and identified the first case of D. repens infection in Eurasian badgers in Poland and the second in Europe.

Haematological indices and immune response profiles in dogs naturally infected and co-infected with Dirofilaria repens and Babesia canis

Co-infections with Dirofilaria repens and Babesia canis are rarely reported in the literature and there is very limited knowledge of their impact on canine health. Central Poland is endemic for both parasites, posing a risk of co-infections in dogs. To evaluate the impact of co-infection with B. canis and D. repens on canine health, four groups of dogs were examined: healthy dogs, dogs infected with B. canis, dogs infected with D. repens and dogs co-infected with both species. Blood parameters indicative of anaemia, kidney and liver damage were analysed statistically. Additionally, expression levels of immune response genes were quantified and compared, to define the type of immune response typically encountered in single- and co-infections. In dogs infected with D. repens, no major alterations in blood parameters were observed. Dogs infected with B. canis suffered from anaemia, kidney and liver insufficiency. In contrast, dogs co-infected with D. repens and B. canis showed milder alternation in blood biochemical parameters associated with liver (ALP activity) and kidney (serum urea and creatinine levels) dysfunction, compared to dogs infected only with B. canis. The expression of genes associated with cellular (Th1-mediated) (STAT4 and INF-γ), humoral (Th2-mediated) (STAT6, GATA3, SOCS3, IL-13) and regulatory (IL-10) responses was quantified. For this analysis, dogs infected with B. canis were divided into two groups-'Babesia 1' (mild babesiosis), 'Babesia 2' (severe babesiosis). All the tested factors, except INF-γ, were found to be expressed in dogs infected with D. repens. In 'Babesia 1' dogs, expression of GATA3 was highest, while in 'Babesia 2'-INF-γ and SOCS3 dominated. IL-13 expression was predominant in dogs infected with D. repens, and STAT6 and IL-10 predominated in dogs with co-infections.

Filariasis in dogs brought to the Veterinary Teaching Hospital, University of Peradeniya, Sri Lanka

Dirofilariasis is the predominant emerging zoonotic filariasis in the world. The two most frequent filarial worms that infect dogs are Dirofilaria repens and Dirofilaria immitis. This study reports filariasis among dogs brought to the Veterinary Teaching Hospital (VTH) at the University of Peradeniya and signifies the first molecular characterization of D. repens, responsible for an emerging zoonotic filarial disease in Sri Lanka. Blood samples were collected and were morphologically analyzed using Modified Knott's Technique, followed by molecular analyses. The difference in filariasis prevalence among gender, breed, and age categories was analyzed using a chi-square test. Infection intensities were analyzed using the Mann-Whitney U test and the Kruskal Wallis test. The dogs were brought to the clinic for either vaccination and/or for a regular checkup, and most were sick having non-specific clinical signs. Among the 87 dogs tested, 27.6% were positive for Dirofilaria. Conventional PCR and bi-directional sequencing of genomic DNA of microscopically tested positive samples revealed that the species in Sri Lanka was D. repens. The infection was significantly higher in males (39.1%) than in females (14.6%; χ² = 0.447, p = 0.011), though it is not significant between puppies (age < 1 year) and adult dogs. More crossbred dogs were infected compared to older and purebred dogs. There was no difference in intensity of infection based on their gender, age, or breed. Sequences obtained from the current study were unique and were only 63% identical to those of D. repens reported from South India. The high number of Dirofilaria infections in domestic dogs indicates a potential reservoir for emerging human dirofilariasis cases in Sri Lanka. Thus, morphological and molecular diagnosis, along with epidemiological assessment of these zoonoses, is critical for the formulation of effective public health programs and control mechanisms.

The long-distance relationship between Dirofilaria and the UK: case report and literature review

Over the last two decades, vector-borne pathogens (VBPs) have changed their distribution across the globe as a consequence of a variety of environmental, socioeconomic and geopolitical factors. Dirofilaria immitis and Dirofilaria repens are perfect exemplars of European VBPs of One Health concern that have undergone profound changes in their distribution, with new hotspots of infection appearing in previously non-endemic countries. Some areas, such as the United Kingdom, are still considered non-endemic. However, a combination of climate change and the potential spread of invasive mosquito species may change this scenario, exposing the country to the risk of outbreaks of filarial infections. Only a limited number of non-autochthonous cases have been recorded in the United Kingdom to date. These infections remain a diagnostic challenge for clinicians unfamiliar with these "exotic" parasites, which in turn complicates the approach to treatment and management. Therefore, this review aims to (i) describe the first case of D. repens infection in a dog currently resident in Scotland, (ii) summarise the available literature on Dirofilaria spp. infections in both humans and animals in the United Kingdom and (iii) assess the suitability of the United Kingdom for the establishment of these new VBPs.

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

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

Tick-Borne Pathogens, Babesia spp. and Borrelia burgdorferi s.l., in Sled and Companion Dogs from Central and North-Eastern Europe

Ticks are important vectors of numerous pathogens of medical and veterinary significance. The aim of the current study was to determine the prevalence of Babesia spp. and Borrelia burgdorferi s.l. in sled and pet dogs from Central and North-Eastern Europe. Neither Babesia spp. nor Borrelia burgdorferi s.l. infections were detected in sled dogs from seven countries (Poland, Lithuania, Latvia, Estonia, Belarus, Russia and Finland). The DNA of Babesia spp. was detected in 100% of symptomatic and 5.4% of asymptomatic pet dogs from Poland. Similarly, the DNA of Babesia spp. was identified in 82% of symptomatic and 3.8% of asymptomatic pet dogs from Ukraine. The DNA of Borrelia burgdorferi s.l. was detected in 4.4% of pet dogs. Molecular typing confirmed the presence of Babesia canis and Borrelia burgdorferi sensu stricto (s.s.) in selected samples. Four dogs were co-infected by B. canis and Borrelia burgdorferi s.l. Tick-borne pathogens constitute a serious health threat to pet dogs in Central and South-Eastern Europe, but were not observed among sled dogs from the same region of Europe nor in the Baltic countries.

Subconjunctival human dirofilariasis by Dirofilaria repens in the Mediterranean Basin

Purpose

Human dirofilariasis cases have increased in Europe for the last few decades. We document an autochthonous case of dirofilariasis infection in the subconjunctival space of a 60-year-old Spanish man.

Observations

The patient presented with pain in his right eye, which was diagnosed as epi-scleritis. In spite of the treatment administered, no improvement was reported. An external exam showed conjunctival congestion on the temporal part of the right eye bulbar conjunctiva. The anterior chamber showed no flare or cells in both eyes and dilated fundus exam was normal. Nevertheless, a long whitish vermiform mobile mass was detected under the conjunctiva in the temporal part of the right eye. The worm was surgically removed and diagnosed morphologically and also molecularly as Dirofilaria repens. This species uses dogs and wild canids as definitive hosts and principal reservoirs, while mosquito species are transmitters. Humans act as accidental hosts, and clinical manifestations depend on the location of the worm in the organs and tissues.

Conclusions and importance

The correct diagnosis and control of subcutaneous/ocular dirofilariasis by D. repens require several professionals under the One Health approach to deal with this zoonotic disease, which poses a serious public health problem, at least in the Mediterranean Basin.

The emergence of Dirofilaria repens in a non-endemic area influenced by climate change: dynamics of transmission using a mathematical model

Dirofilaria repens is a nematode affecting domestic and wild canids, transmitted by several species of mosquitoes of different genera. It usually causes a non-pathogenic subcutaneous infection in dogs and is the principal agent of human dirofilariasis in the Old World. The geographic distribution of D. repens is changing rapidly, and several factors contribute to the spread of the infection to non-endemic areas. A mathematical model for transmission of Dirofilaria spp. was built, using a system of ordinary differential equations that consider the interactions between reservoirs, vectors, and humans. The transmission simulations of D. repens were carried out considering a projection in time, with intervals of 15 and 100 years. For the dynamics of the vector, seasonal variations were presented as series with quarter periodicity during the year. The results of the simulations highlight the peak of contagions in the reservoir and in humans, a product of the action of the vector when it remains active throughout the year. A 300% infection increase in the reservoir was observed during the first decade and remains present in the population with a representative number of cases. When the vector maintains its density and infectivity during the year, the incidence of the infection in humans increases. Accumulated cases amount to 45 per 100,000 inhabitants, which corresponds to a cumulative incidence of 0.05%, in 85 years. This indicates that early prevention of infection in canids would significantly reduce the disease, also reducing the number of accumulated cases of human dirofilariasis by D. repens. The interaction between the simulations generated by the model highlights the sensitivity of the epidemiological curve to the periodicity of seasonality, reaffirming the hypothesis of the probability of movement of the zoonotic disease to non-endemic areas, due to climate change.

Identity of Microfilariae Circulating in Dogs from Western and South-Western Romania in the Last Decade

Dirofilaria infections in dogs are recognized as widespread mosquito-borne diseases with zoonotic potential, that are caused by the filarioid nematode (Onchocercidae) species Dirofilaria immitis and Dirofilaria repens. The long-term survey conducted in western and south-western Romania was undertaken in order to provide valuable data on the occurrence of Dirofilaria infections in dogs. Blood samples from 1088 dogs, originating from 73 localities of 11 western and south-western counties in Romania, were collected and examined using the modified Knott test. Subsequently, all of the microscopically positive samples were subjected to molecular analysis for confirmation. Altogether, the data obtained showed the percentage of dogs with circulating microfilariae to be 21.42% (233/1088) of dogs tested in the investigated region. The identified species, in cases of monoinfections, were D. immitis, D. repens, and Acanthocheilonema reconditum in 106 (9.74%) samples, 102 (9.38%) samples, and 1 (0.09%) sample, respectively. Twenty-four (2.21%) samples were simultaneously positive for D. immitis and D. repens. There was no association (p > 0.05) between infection status and breed; however, sex and lifestyle were positively associated (p < 0.05) with the percentage of dogs with circulating microfilariae and might be regarded as risk factors for infection. The results of the present investigation indicate potential zoonotic risks for humans living in the screened area and support the imperative to increase awareness among both veterinarians and physicians, regarding the continuous spread of these zoonotic filariae.

Dirofilaria spp. and Angiostrongylus vasorum: Current Risk of Spreading in Central and Northern Europe

In the past few decades, the relevance of Dirofilaria immitis and Dirofilaria repens, causing cardiopulmonary and subcutaneous dirofilariosis in dogs and cats, and of Angiostrongylus vasorum, causing canine angiostrongylosis, has steadily increased in Central and Northern Europe. In this review, a summary of published articles and additional reports dealing with imported or autochthonous cases of these parasites is provided for Central (Austria, Czechia, Germany, Hungary, Luxemburg, Poland, Slovakia, Slovenia, and Switzerland) and Northern (Denmark, Finland, Iceland, Norway, and Sweden) Europe. Research efforts focusing on Dirofilaria spp. and A. vasorum have varied by country, and cross-border studies are few. The housing conditions of dogs, pet movements, the spread of competent vectors, and climate change are important factors in the spread of these nematodes. Dogs kept outside overnight are a major factor for the establishment of Dirofilaria spp. However, the establishment of invasive, diurnal, synanthropic, competent mosquito vectors such as Aedes albopictus may also influence the establishment of Dirofilaria spp. The drivers of the spread of A. vasorum remain not fully understood, but it seems to be influenced by habitats shared with wild canids, dog relocation, and possibly climatic changes; its pattern of spreading appears to be similar in different countries. Both Dirofilaria spp. and A. vasorum merit further monitoring and research focus in Europe.

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

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

Low risk of transmission of pathogenic bacteria between children and the assistance dog during animal-assisted therapy if strict rules are followed

This study explored the bacterial transmission between patients and dogs during dog-assisted therapy (DAT). Twenty children (55% girls) with a median age of 7 years (range 3-17 years) were included. Two dogs assisted and the conditions were more restricted hygienically with dog 2. Samples from child and dog were collected and cultured before and after each DAT visit. The results showed that dog 1 transmitted bacteria repeatedly to the children. No bacteria were transmitted with dog 2. In conclusion, exchange of bacteria can occur between dog and child during DAT, but it can be reduced by simple infection control measures.