Anti-Hepatozoon canis serum antibodies and gamonts in naturally-occurring canine monocytic ehrlichiosis

Clinical presentation, diagnostic investigations, treatment protocols and outcomes of dogs diagnosed with tick-borne diseases living in the United Kingdom: 76 cases (2005-2019)

OBJECTIVES

To report the presence of tick-borne diseases in dogs living in the United Kingdom.

MATERIALS AND METHODS

Dogs with a final diagnosis of tick-borne diseases made between January 2005 and August 2019 at seven referral institutions in the United Kingdom were included in the study.

RESULTS

Seventy-six dogs were included: 25 were diagnosed with ehrlichiosis, 23 with babesiosis, eight with Lyme borreliosis and six with anaplasmosis. Fourteen dogs had co-infections with two or three pathogens. Except for those dogs with anaplasmosis and Lyme borreliosis, most dogs with tick-borne diseases had a history of travel to or from endemic countries. However, three dogs with ehrlichiosis, and one dog each infected with Babesia canis and Babesia vulpes did not have any history of travel. A variety of non-specific clinical signs and laboratory abnormalities were reported. Targeted treatment was successful at achieving clinical remission in 64 (84%) dogs.

CLINICAL SIGNIFICANCE

Even in non-endemic areas, veterinary surgeons should consider tick-borne diseases in dogs with compatible clinical presentation and laboratory findings and especially where there is a history of travel. As autochthonous transmission of tick-borne-pathogens does occur, an absence of travel should not rule out tick-borne diseases. Specific diagnostic testing is required to confirm infection, and this enables prompt targeted treatment and often a positive outcome.

An innovative and user-friendly smartphone-assisted molecular diagnostic approach for rapid detection of canine vector-borne diseases

Present-day diagnostic tools and technologies for canine diseases and other vector-borne parasitic diseases hardly meet the requirements of an efficient and rapid diagnostic tool, which can be suitable for use at the point-of-care in resource-limited settings. Loop-mediated isothermal amplification (LAMP) technique has been always a method of choice in the development and validation of quick, precise, and sensitive diagnostic assays for pathogen detection and to reorganize point-of-care (POC) molecular diagnostics. In this study, we have demonstrated an efficient detection system for parasitic vector-borne pathogens like Ehrlichia canis and Hepatozoon canis by linking the LAMP assay to a smartphone via a simple, inexpensive, and a portable “LAMP box,” All the components of the LAMP box were connected to each other wirelessly. This LAMP box was made up of an isothermal heating pad mounted below an aluminum base which served as a platform for the reaction tubes and LAMP assay. The entire setup could be connected to a smartphone via an inbuilt Wi-Fi that allowed the user to establish the connection to control the LAMP box. A 5 V USB power source was used as a power supply. The sensitivity of the LAMP assay was estimated to be up to 10⁻⁶ dilution limit using the amplified, purified, and quantified specific DNA templates. It can also serve as an efficient diagnostic platform for many other veterinary infectious or parasitic diseases of zoonotic origin majorly towards field-based diagnostics.

Hepatozoon canis in hunting dogs from Southern Italy: distribution and risk factors

Hepatozoon canis is a hemoprotozoan organism that infects domestic and wild carnivores throughout much of Europe. The parasite is mainly transmitted through the ingestion of infected ticks containing mature oocysts. The aims of the present survey were to determine the prevalence of H. canis in hunting dogs living in Southern Italy and to assess potential infection risk factors. DNA extracted from whole blood samples, collected from 1433 apparently healthy dogs living in the Napoli, Avellino, and Salerno provinces of Campania region (Southern Italy), was tested by a quantitative real-time polymerase chain reaction (qPCR) assay to amplify H. canis. Furthermore, the investigated dog population was also screened by qPCR for the presence of Ehrlichia canis, a major tick-borne pathogen in Southern Italy, in order to assess possible co-infections. Two hundred dogs were H. canis PCR-positive, resulting in an overall prevalence of 14.0% (CI 12.2–15.9). Breed category (P < 0.0001), hair coat length (P = 0.015), and province of residence (P < 0.0001) represented significant risk factors for H. canis infection. The presence of H. canis DNA was also significantly associated with E. canis PCR positivity (P < 0.0001). Hunting dogs in Campania region (Southern Italy) are frequently exposed to H. canis, and the infection is potentially associated with close contact with wildlife. Further studies are needed to assess the pathogenic potential of H. canis, as well as the epidemiological relationships between hunting dogs and wild animal populations sharing the same habitats in Southern Italy.

Evaluation of a Loop-Mediated Isothermal Amplification Technique for the Rapid Visual Detection of Hepatozoon canis Infection

BACKGROUND

Laboratory diagnosis of Hepatozoon canis infection is tedious, especially in chronic and/or latent infections.

PURPOSE

The study was planned to develop a simple read out loop mediated isothermal amplification (LAMP) assay targeting a partial 18S rRNA gene of H. canis with naked eye visualisation of LAMP products.

METHODS

A LAMP assay was employed to assess the DNA amplification by adding SYBR Green I dye for naked eye inspection of DNA accumulating in reaction tubes. Positive amplification was read through observation of change in colour of reaction mixture following addition of dye. The visual results were further verified with those of agarose gel electrophoresis. Genomic DNA of other haemoparasites of dog viz. Babesia vogeli, B. gibsoni, Ehrlichia canis and Trypanosoma evansi along with no-template control were used to determine the specificity of assay.

RESULTS

Among the 109 blood samples presented at Small Animal Clinics, Teaching Veterinary Clinical Complex, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab (India) tested, 39 revealed colour change from orange to green indicating positive reaction while 70 were negative as revealed by no colour change. The results of visual inspection were comparable to those obtained by agarose gel electrophoresis. The LAMP primers specifically amplified H. canis DNA, whereas no amplification was detected in DNA samples of other haemoparasites and no-template control revealing specificity of the assay. The diagnostic sensitivity and specificity (95% CI) of visual LAMP assay with respect to microscopy in detection of H. canis varied from 100% (15.81-100.00%) and 65.42% (55.61-74.35%), respectively.

CONCLUSION

The present investigation has developed a specific and rapid LAMP assay for the detection of H. canis, using SYBR Green I dye, which has practical applications for the screening of field samples.

Development of loop-mediated isothermal amplification (LAMP) assay for detection of Hepatozoon canis infection in dogs

The laboratory diagnosis of canine hepatozoonosis, caused by Hepatozoon canis is tedious, especially in chronic and latent infections. In the present investigation, a loop mediated isothermal amplification (LAMP) assay was developed and standardized targeting the partial 18S rRNA gene (GenBank accession no. KU096058). The LAMP primers specifically amplified H. canis DNA, whereas no amplification was detected in DNA samples from dogs infected with Babesia vogeli, B. gibsoni, Ehrlichia canis and Trypanosoma evansi, and no amplification was observed in DNA samples from H. canis-free dogs. The threshold sensitivity level of the assay was determined to be 15 fg of genomic DNA of H. canis. Furthermore, evaluation of blood samples collected from 250 dogs presented at Small Animal Clinics, Teaching Veterinary Clinical Complex, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab (India) was carried out for the presence of H. canis by microscopy, 18S PCR assay and LAMP assay. Of the total samples subjected to these tests, LAMP detected H. canis in 75 samples, while 18S PCR and microscopy detected H. canis in 28 and 9 samples, respectively. The present investigation has developed, for the first time, a highly sensitive, specific and rapid LAMP assay for the detection of H. canis, which has practical applications for the screening of field samples.

Hepatozoon canis in three imported dogs: a new tickborne disease reaching the United Kingdom

An increasing number of non-endemic vectorborne pathogens have been described in dogs imported to the UK in the past two decades. Recently, an outbreak of canine babesiosis in south-east England has raised veterinary awareness with regard to the impact of such diseases on the UK canine population. Canine hepatozoonosis, caused by Hepatozoon canis and transmitted by the ingestion of Rhipicephalus sanguineus ticks, is widespread in the Mediterranean basin. Herein we describe the first three molecularly confirmed clinical cases of canine hepatozoonosis in dogs imported into the UK. Veterinarians in the UK should be aware of H canis as a potential infection in imported dogs, especially in the face of the expanding distribution of R sanguineus ticks in Europe.

Canine pancytopoenia in a Mediterranean region: a retrospective study of 119 cases (2005 to 2013)

OBJECTIVES

To further clarify the causes of pancytopoenia and to investigate whether underlying cause or severity were associated with survival in an area endemic for vector-borne pathogens.

METHODS

Retrospective review of medical records of 119 dogs with and 238 dogs without pancytopoenia.

RESULTS

Mixed-breed dogs and dogs younger than one year had higher odds of being pancytopoenic. The most common diagnoses included monocytic ehrlichiosis (n=42), leishmaniasis (n=28) and parvoviral enteritis (n=19). The mean white blood cell counts were lower in dogs with ehrlichiosis and parvoviral enteritis compared to dogs with leishmaniasis, while platelet counts were lower in ehrlichiosis compared to leishmaniasis or parvoviral enteritis. Total protein concentrations were lower in dogs with parvoviral enteritis compared to ehrlichiosis and leishmaniasis. Higher haematocrit, platelet and white cell counts were associated with better odds of survival.

CLINICAL SIGNIFICANCE

Infectious diseases appear to be the leading causes of canine pancytopoenia in endemic areas; severe leukopoenia (ehrlichiosis, parvoviral enteritis), thrombocytopoenia (ehrlichiosis) and hypoproteinaemia (parvoviral enteritis), represented potentially useful disease-specific diagnostic determinants. The severity of pancytopoenia significantly affects the clinical outcome.

Canine tick-borne pathogens in Cyprus and a unique canine case of multiple co-infections

Canine tick-borne pathogens such as Ehrlichia canis and Hepatozoon canis are widespread in the Mediterranean basin but have never been reported or investigated in Cyprus. We describe herein the presence of canine tick-borne pathogens in three dogs with clinical signs compatible with vector-borne diseases from Paphos area of Cyprus. Molecular and phylogenetic analysis revealed the presence of E. canis, Anaplasma platys, H. canis, Babesia vogeli and Mycoplasma haemocanis in Cyprus. One dog co-infected with E. canis, H. canis, B. vogeli and M. haemocanis is, to the best of our knowledge, the first report of this multiple co-infection in dogs. The tick-borne pathogens reported in the current study should be considered in the differential diagnoses in dogs exposed to ticks in Cyprus.

Molecular detection and characterization of Hepatozoon spp. in dogs from the central part of Turkey

Canine hepatozoonosis is a tick-borne protozoal disease caused by Hepatozoon spp. Two species of Hepatozoon are currently known to infect dogs as Hepatozoon canis and H. americanum. Although H. canis generally causes a chronic infection with relatively mild clinical alterations compared to H. americanum, infection by H. canis can be life-threatening. The disease is widespread in USA, Africa, Europe, South America, and Asia. To determine the frequency of infection with Hepatozoon spp. in stray dogs from Central Anatolia Region of Turkey, a total of 221 blood samples collected over a three-year period were evaluated by using genus specific Polymerase Chain Reaction (PCR) designed to amplify a fragment of 666bp located in 18 S rRNA gene of Hepatozoon spp. Eight (3.61%) blood samples were positive for Hepatozoon spp. For the classification of species, all positive PCR products were purified with a PCR purification kit and sequenced. Sequencing results of eight representative amplicons indicated that 6 were 98-99% identical to the sequence of H. canis and the other 2 sequences were 95-97% identical to the sequence of Hepatozoon spp. So it was named Hepatozoon sp. MF. A phylogenetic tree was constructed from the sequences of the tick-borne agents identified previously and in this study using the neighbor-joining method. The nucleotide sequences were compared to the H. canis sequences reported in Turkey using the nucleotide Basic Local Alignment Search Tool (BLAST) program. The results of this study are significant in terms of the presence of a novel canine Hepatozoon genotype.

Brazilian canine hepatozoonosis

The genus Hepatozoon includes hundreds of species that infect birds, reptiles, amphibians and mammals, in all continents with tropical and subtropical climates. Two species have been described in domestic dogs: H. canis, reported in Europe, Asia, Africa, South America and the United States; and H. americanum, which so far has only been diagnosed in the United States. In Brazil, the only species found infecting dogs is H. canis. The objective of this review was to detail some aspects of canine hepatozoonosis, caused by H. canis, and the main points of its biology, transmission, pathogenicity, symptoms, epidemiology and diagnostic methods, with emphasis on research developed in Brazil.

Canine vector-borne disease in travelled dogs in Germany--a retrospective evaluation of laboratory data from the years 2004-2008

When importing dogs from various Mediterranean countries into Western Europe canine vector-borne infections are often considered as a major issue. Several diseases including babesiosis, leishmaniosis, hepatozoonosis, canine heartworm disease or ehrlichiosis can potentially be endemic in this region and pose a potential health risk for travelling dogs. Information on such infections in travelled dogs is scarce and therefore this study has been undertaken to examine the frequency of vector-borne infections in travelled dogs from the years 2004-2008. A total of 997 samples were screened by direct and/or indirect methods. Total seroprevalence was 7.5% with individual seroprevalence for the 3 species Leishmania spp., Ehrlichia canis and Babesia canis spp. ranging from 3.1 to 4.9%. Total detection rate for pathogens by direct methods was 3.5%. Nineteen Giemsa-stained blood smears were positive for large Babesia. None of the samples screened for microfilariae by Knott's test or for Dirofilaria immitis antigen by DiroChek(®) were positive. Using PCR methods Leishmania-DNA was detected in 1/42 samples but none of 59 animals screened for E. canis-DNA was positive. The prevalence values as established by indirect and direct pathogen detection are considered as rather low.

Perspectives on canine and feline hepatozoonosis

Two species of Hepatozoon are currently known to infect dogs and cause distinct diseases. Hepatozoon canis prevalent in Africa, Asia, southern Europe, South America and recently shown to be present also in the USA causes infection mainly of hemolymphoid organs, whereas Hepatozoon americanum prevalent in the southeastern USA causes myositis and severe lameness. H. americanum is transmitted by ingestion of the Gulf Coast tick Amblyomma maculatum and also by predation on infected prey. H. canis is transmitted by Rhipicephalus sanguineus, in South America also by Amblyomma ovale, and has also been shown to be transmitted transplacentally. Hepatozoonosis of domestic cats has been described mostly from the same areas where canine infection is present and the exact identity of the species which infect cats, their pathogenicity and vectors have not been elucidated. The diagnosis of hepatozoonosis is made by observation of gamonts in blood smears, histopathology, PCR or serology. The main treatment for H. canis is with imidocarb dipropionate whereas H. americanum infection is treated with an initial combination of trimethoprim-sulfadiazine, pyrimethamine and clindamycin followed by maintenance with decoquinate. Treatment for both diseases has not been reported to facilitate complete parasite elimination and new effective drugs are needed for the management of these infections. Prevention of hepatozoonosis should be based on avoidance of oral ingestion of infected tick vectors and infected prey.

Occurrence of Hepatozoon sp. in dogs in the urban area originating from a municipality in southeastern Brazil

The occurrence of Hepatozoon sp. infection in dogs was evaluated in the urban area of Uberlândia, Minas Gerais, Brazil. The study involved 300 animals, 120 from the Veterinary Hospital of the Federal University of Uberlândia's Faculty of Veterinary Medicine, 80 from private clinics, and 100 from the Animal Protective Association (APA). Among these animals, 7.66% presented Hepatozoon sp. gamonts inside neutrophils. No statistically significant difference was found among the diagnoses based on capillary and venous blood smears, but a statistical significance was identified in age range and breed. The main signs and symptoms the animals presented were pale mucous membranes, swollen lymph nodes, ocular discharge and pain in response to renal palpation. All the ticks collected were of the species Rhipicephalus sanguineus and no oocyst of the parasite was found in the hemolymph of the ixodidae. The findings of this study reinforce the presence of Hepatozoon sp. infecting dogs in Uberlândia, MG, with age and breed possibly related to the infection. The symptoms presented by the animals were consistent with those reported by other researchers.

A retrospective study of 61 cases of spontaneous canine epistaxis (1998 to 2001)

OBJECTIVES

To determine the prevalence and identify possible clinicopathologic indicators of the diseases associated with canine epistaxis.

METHODS

The medical records of 61 dogs with epistaxis were reviewed.

RESULTS

Systemic diseases, diagnosed in fifty-six dogs, included canine leishmaniasis in twenty-three dogs, canine monocytic ehrlichiosis in twenty-two, concurrent canine leishmaniasis and canine monocytic ehrlichiosis in six, rodenticide toxicity in two and primary immune-mediated thrombocytopenia, suspected oestrogen toxicity and systemic arterial hypertension in one dog each. Intranasal diseases were documented in the remaining five dogs, including transmissible venereal tumour in three dogs, and nasal adenocarcinoma and nasal aspergillosis in one dog each. Mucosal pallor and a generalised bleeding tendency were significantly more common among dogs with canine monocytic ehrlichiosis compared with those with canine leishmaniasis, whereas the opposite was true for peripheral lymphadenomegaly. Also, dogs with canine monocytic ehrlichiosis presented with pancytopenia more frequently compared with those with canine leishmaniasis; in the latter dogs, the median values of haematocrit, leucocyte and platelet counts and serum total protein concentrations were higher.

CLINICAL SIGNIFICANCE

Canine leishmaniasis and canine monocytic ehrlichiosis are the leading causes of canine epistaxis in Greece. Mucosal pallor, bleeding tendency and pancytopenia are more likely to be indicative of canine monocytic ehrlichiosis, as opposed to peripheral lymphadenomegaly and hyperproteinaemia in canine leishmaniasis.

Clinical signs and clinicopathologic abnormalities in dogs with clinical spirocercosis: 39 cases (1996-2004)

OBJECTIVE

To determine clinical signs and clinicopathologic abnormalities in dogs with naturally occurring clinical spirocercosis.

DESIGN

Retrospective case series.

ANIMALS

39 dogs with spirocercosis.

PROCEDURES

Medical records were reviewed, and information on signalment, residence (rural vs urban), owner complaints, physical examination findings, clinicopathologic abnormalities, radiographic and endoscopic findings, and concurrent systemic diseases was recorded.

RESULTS

Hellenic hounds and mixed-breed dogs were overrepresented, compared with a group of 117 control dogs without spirocercosis that were examined because of gastrointestinal tract disease, and mean body weight of dogs with spirocercosis was significantly higher than mean body weight of control dogs. Odynophagia (34 [87%]), regurgitation (24 [62%]), and excessive salivation (14 [36%]) were the most common clinical findings. The most common radiographic abnormalities were a mass in the caudodorsal aspect of the mediastinum (15/35 [43%]) and spondylitis of the caudal thoracic vertebrae (10 [29%]). Parasitic nodules were seen during esophagoscopy in all 39 dogs. Normocytic, normochromic, nonregenerative anemia; neutrophilic leukocytosis; hyperproteinemia; and high alkaline phosphatase activity were significantly more common in dogs with spirocercosis than in a control group of 56 healthy dogs. Concurrent systemic diseases, mainly leishmaniosis, dirofilariosis, and monocytic ehrlichiosis, were documented in 14 (36%) dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that clinical spirocercosis occurs more often in young-adult, large-breed dogs. Nonregenerative anemia, neutrophilic leukocytosis, hyperproteinemia, and high alkaline phosphatase activity may be useful clinicopathologic indicators of this disease.