Diagnosis of canine monocytotropic ehrlichiosis (Ehrlichia canis): An overview

Molecular detection of Anaplasma platys and Ehrlichia canis in dogs from Kabylie, Algeria

Ehrlichia canis and Anaplasma platys are bacteria belonging to the Anaplasmataceae family that cause acute, self-limiting and sometimes fatal vector-borne infections in dogs. These bacteria have been reported worldwide and are transmitted mainly by Rhipicephalus sanguineus. Aside from a report on E. canis once in 1935, no other Anaplasmataceae bacteria have been reported in Algeria to date. The aim of this study was to identify the microbial species implicated in ehrlichiosis and anaplasmosis by a molecular epidemiological survey in dogs. The study was carried out in Kabylie, in northeast Algeria. Sampling was performed in 11 municipalities in the province of Tizi Ouzou and 2 municipalities in the province of Béjaïa. Peripheral blood samples from 110 dogs were screened by qPCR, which is capable of identifying most Anaplasmataceae bacteria. Out of 110, a total of 13 samples screened positive (7/110 E. canis and 6/110 A. platys), and two genetic variants of A. platys and one of E. canis were identified. This is the first study to report the presence of A. platys in dogs from Algeria using a molecular investigative method. This survey was conducted in early spring. As tick activity can affect the prevalence of these pathogens in dogs, further investigations are needed to establish the year-round prevalence of these infections.

Molecular Diagnosis of Ehrlichia canis in Dogs and Ticks Rhipicephalus sanguineus (Acari: Ixodidae) in Yucatan, Mexico

Ehrlichia canis is the etiological agent behind canine monocytic ehrlichiosis, and the tick Rhipicephalus sanguineus (Latreille) is its main vector. Blood smear and nested polymerase chain reaction (PCR) techniques were used to identify E. canis infection in dogs and R. sanguineus, and explore factors possibly associated with infection in dogs in Yucatan, Mexico. Blood samples were taken and ticks R. sanguineus collected from 50 dogs (10 house dogs and 40 in an animal control center). Data were collected on dog age, sex, body condition, and signs associated with platelet deficiencies (epistaxis). Blood smears were analyzed to identify E. canis morulae and generate platelet counts. Nested PCR analysis was done on blood samples and 200 ticks. A χ(2) test was done to identify factors associated with the E. canis infection in the tested dogs. The overall prevalence for infection, as determined by PCR, was 36% (18 out of 50). All positive dogs were from samples collected from the animal shelter, representing prevalence, for this sampling site, of 45% (18 out of 40). Morulae in monocytes were identified in only 4% of samples. Dog origin (i.e. animal control center) was the only variable associated with E. canis infection (P < 0.01). Male ticks had a higher (P < 0.05) infection rate than female ticks (24.5 vs 13.5%). It is concluded that E. canis infection is present in both dogs and the brown dog ticks R. sanguineus in Yucatan, Mexico.

Canine vector-borne co-infections: Ehrlichia canis and Hepatozoon canis in the same host monocytes

The protozoon Hepatozoon canis and the rickettsia Ehrlichia canis are tick-borne pathogens, transmitted by Rhipicephalus sanguineus, which cause canine hepatozoonosis and canine monocytic ehrlichiosis, respectively. Co-infection of the same host monocytes with H. canis and E. canis confirmed by molecular characterization of the infecting agents and quantitative assessment of co-infected cells is described for the first time in three naturally-infected dogs. Blood smear evaluation indicated that at least 50% of the leukocytes infected with H. canis gamonts contained E. canis morulae. Co-infection of the same host cell demonstrated in this report suggests that infection with one pathogen may permit or enhance invasion or prolonged cellular survival of the other.

Azitromicina no tratamento da erlichiose monocítica em cães naturalmente infectados

Os objetivos deste trabalho foram avaliar a eficácia do tratamento com azitromicina em cães naturalmente infectados por E. canis e acompanhar a evolução clínico-hematológica dos animais. Dez cães, com diagnóstico positivo para E. canis por meio do teste de Elisa Snap 4Dx, foram distribuídos em dois grupos, sem tratamento e tratados com azitromicina, 20 mg/kg, via oral, uma vez ao dia, durante sete dias. Além do exame físico diário foram realizados hemogramas, esfregaços de ponta de orelha para a pesquisa de mórulas e nested PCR antes do tratamento e pós-tratamento. Verificou-se que o tratamento não foi eficiente, uma vez que não desapareceram os sinais clínicos, assim como não houve retorno à normalidade dos valores do hemograma nos cães, assim como ausência de eliminação de E. canis.

Intraoperative bleeding in dogs from Grenada seroreactive to Anaplasma platys and Ehrlichia canis

BACKGROUND

Frequent exposure of Grenadian dogs to Rhipicephalus sanguineus results in Anaplasma platys, and Ehrlichia canis seroreactivity. During elective surgeries, substantial intraoperative hemorrhage occurs in some seroreactive dogs.

OBJECTIVES

To assess hemostatic parameters and bleeding tendencies as well as prevalence of PCR positivity in apparently healthy A. platys and E. canis seroreactive and seronegative free-roaming dogs from Grenada.

ANIMALS

Forty-seven elective surgery dogs allocated to 4 groups: Seronegative control (n = 12), A. platys (n = 10), E. canis (n = 14) and A. platys, and E. canis (n = 11) seroreactive.

METHODS

Preoperatively, hemostasis was assessed by platelet count, prothrombin time, activated partial thromboplastin time, and buccal mucosal bleeding time. Intra- and postoperative bleeding scores were subjectively assigned. Blood, spleen, bone marrow, and lymph node aspirates were tested by PCR.

RESULTS

Bleeding scores in dogs coseroreactive for A. platys and E. canis were higher (P = .015) than those of seronegative dogs. A. platys DNA was amplified from 7/21 (33%) A. platys seroreactive dogs and from 1 E. canis seroreactive dog; E. canis DNA was amplified from 21/25 (84%) E. canis seroreactive dogs. E. canis DNA was amplified most often from blood, whereas A. platys DNA was amplified most often from bone marrow.

CONCLUSIONS AND CLINICAL IMPORTANCE

Apparently healthy, free-roaming dogs coseropositive for A. platys and E. canis may have increased intraoperative bleeding tendencies despite normal hemostatic parameters. Future investigations should explore the potential for vascular injury as a cause for bleeding in these dogs. Improved tick control is needed for dogs in Grenada.

Colorimetric detection of Ehrlichia canis via nucleic acid hybridization in gold nano-colloids

Canine monocytic ehrlichiosis (CME) is a major thick-bone disease of dog caused by Ehrlichia canis. Detection of this causal agent outside the laboratory using conventional methods is not effective enough. Thus an assay for E. canis detection based on the p30 outer membrane protein gene was developed. It was based on the p30 gene amplification using loop-mediated isothermal DNA amplification (LAMP). The primer set specific to six areas within the target gene were designed and tested for their sensitivity and specificity. Detection of DNA signals was based on modulation of gold nanoparticles' surface properties and performing DNA/DNA hybridization using an oligonucleotide probe. Presence of target DNA affected the gold colloid nanoparticles in terms of particle aggregation with a plasmonic color change of the gold colloids from ruby red to purple, visible by the naked eye. All the assay steps were completed within 90 min including DNA extraction without relying on standard laboratory facilities. This method was very specific to target bacteria. Its sensitivity with probe hybridization was sufficient to detect 50 copies of target DNA. This method should provide an alternative choice for point of care control and management of the disease.

Cold agglutinin activity in 2 dogs

A 5-year-old neutered male Mastiff and an 8-year-old spayed female Labrador Retriever were presented to the University of Minnesota Veterinary Medical Center. The Mastiff was presented for evaluation of lameness and pyoderma one month prior in Missouri, where he tested positive for Ehrlichia canis by serum ELISA test, treated with doxycycline. PCR for Ehrlichia sp, Anaplasma sp, Babesia sp, and Bartonella sp, and PCR for antigen receptor rearrangement were negative, serum protein electrophoresis (SPE) revealed polyclonal gammopathy, and mildly reactive lymphoid cells were seen cytologically. The Labrador presented with a proliferative rostral mandibular gingival mass and lipomas for further presurgical evaluation of cold agglutinin activity documented by a commercial laboratory 2 years earlier prior to removal of a grade II mast cell tumor. This dog had a negative SNAP4Dx, normal SPE, and persistently increased serum ALP activity and polyuria/polydipsia suggestive for hyperadrenocorticism. Both dogs had markedly agglutinated RBC in the EDTA samples that dispersed with warming, and normal plasma color. Cold agglutinin activity was demonstrated by direct saline agglutination testing using whole blood and washed erythrocytes demonstrating agglutination at 30°C, 25°C, 15°C, and 4°C, but not at 37°C. CBC results (ADVIA 2120i) from the Mastiff revealed no significant differences in the RBC results obtained at room temperature (RT) and at 37°C; however, the RT run demonstrated negative bias in neutrophil and platelet concentrations attributed to rapid RBC settling. This uncommon hematologic condition may cause artifacts on the automated leukogram and platelet count, and may be subclinical for long periods.

Seroprevalence of some vector-borne infections of dogs in Hungary

The first comprehensive study on the prevalence of canine vector-borne pathogens (Anaplasma phagocytophilum, Borrelia burgdorferi, Ehrlichia canis, and Dirofilaria immitis) was carried in Hungary because, except for babesiosis and dirofilariosis caused by Dirofilaria repens, there were no data on their regional distribution and prevalence. In 2011 and 2012, 1305 blood samples were collected from randomly selected, apparently healthy pet dogs in 167 localities of 19 counties of Hungary. All sera samples from dogs were screened for simultaneous qualitative detection of circulating antibodies to E. canis and B. burgdorferi sensu lato and A. phagocytophilum and D. immitis antigen using SNAP(®) 4Dx (IDEXX Laboratories). Overall, 170 dogs (13.0%; 95% confidence interval [CI] 11-15) were serologically positive to one or more of the tested pathogens. A. phagocytophilum was the most prevalent pathogen detected in 102 dogs by antibody titers (7.9%, 95% CI 6.5-9.5), followed by D. immitis (2.4%, 95% CI 1.0-4.0, n=64) and B. burgdorferi (0.4%, 95% CI 0.0-1.1, n=11) out of 1305 tested dogs. The least prevalent infection was with E. canis, with only two positive dogs (0.16%, 95% CI 0.03-0.6). Co-infection was found in eight dogs (0.61%, 95% CI 0.29-1.21), of which seven were seropositive to two pathogens (five with A. phagocytophilum and D. immitis, two with A. phagocytophilum and B. burgdorferi). One dog was serologically positive to three pathogens (A. phagocytophilum, B. burgdorferi, and D. immitis). Purebred and crossbred animals did not show significantly different levels of seropositivity. There was no significant association between the gender and the results of diagnostic testing. Logistic regression analysis showed a higher chance of seropositivity in the older dogs.

First report of Babesia gibsoni in Central America and survey for vector-borne infections in dogs from Nicaragua

Background

Although many vector-borne diseases are important causes of morbidity and mortality in dogs in tropical areas and potential zoonoses, there is little information on these conditions in Central America.

Methods

Seven qPCRs for vector-borne pathogens were performed on a Roche LightCycler PCR Instrument to investigate their prevalence in a convenience sample of whole blood samples from apparently healthy dogs in Nicaragua. Also, a qPCR targeting the canine hydroxymethylbilane synthase (HMBS) gene was used as an endogenous internal control and verified the quality and quantity of DNA in the samples was appropriate for the study.

Results

We found DNA of Rickettsia felis (5%), Babesia spp. (26%), Hepatozoon canis (51%), Anaplasma platys (13%) and Ehrlichia canis (56%) in the 39 dogs studied. The qPCRs for Coxiella burnetii and Dirofilaria immitis were negative. Of the 30 (80%) dogs that were positive by qPCR, 12 (31%) were positive for one agent, 11 (28%) for two, 3 (8%) for three, and 4 (10%) for four agents.

Conclusions

This is the first report of B. gibsoni in dogs from Central America and the first recording of vector-borne agents in dogs from Nicaragua. Dogs in Nicaragua are commonly infected with a variety of vector-borne pathogens, some of which may also infect people.

Theileriosis in six dogs in South Africa and its potential clinical significance

Theileriosis is a tick-borne disease caused by a piroplasma of the genus Theileria that can causeanaemia and thrombocytopenia. Its clinical importance for dogs’ remains poorly understood,as only some develop clinical signs. In this study, physical and laboratory findings, treatment and outcomes of six client-owned diseased dogs presented at the Onderstepoort Veterinary Academic Hospital are described retrospectively. In the dogs, Theileria species (n = 4)and Theileria equi (n = 2) were detected by a polymerase chain reaction (PCR)-reverse blothybridisation assay in blood samples, whilst PCR for Babesia, Anaplasma and Ehrlichia were negative. The most common physical findings were pale mucous membranes (five out of six dogs), bleeding tendencies (five out of six dogs) and lethargy (three out of six dogs). All dogs were thrombocytopenic [median 59.5 x 109/L (range 13–199)] and five out of six dogs were anaemic [median haematocrit 18% (range 5–32)]. Bone marrow core biopsies performed in two dogs showed myelofibrosis. Theileriosis was treated with imidocarb dipropionate and the suspected secondary immune-mediated haematological disorders with prednisolone and azathioprine. Five dogs achieved clinical cure and post-treatment PCR performed in three out of five dogs confirmed absence of circulating parasitaemia. An immune-mediated response to Theileria species is thought to result in anaemia and/or thrombocytopenia in diseased dogs with theileriosis. A bleeding tendency, most likely secondary to thrombocytopenia and/or thrombocytopathy, was the most significant clinical finding in these cases. The link between thrombocytopenia, anaemia and myelofibrosis in theileriosis requires further investigation and theileriosis should be considered a differential diagnosis for dogs presenting with anaemia and/or thrombocytopenia in endemic tick-borne disease areas.

Serological survey of Ehrlichia species in dogs, horses and humans: zoonotic scenery in a rural settlement from southern Brazil

The aims of this study were to determine the seroprevalence of Ehrlichia spp. and risk factors for exposure in a restricted population of dogs, horses, and humans highly exposed to tick bites in a Brazilian rural settlement using a commercial ELISA rapid test and two indirect immunofluorescent assays (IFA) with E. canis and E. chaffeensis crude antigens. Serum samples from 132 dogs, 16 horses and 100 humans were used. Fifty-six out of 132 (42.4%) dogs were seropositive for E. canis. Dogs > one year were more likely to be seropositive for E. canis than dogs ≤ one year (p = 0.0051). Ten/16 (62.5%) and 8/16 (50%) horses were seropositive by the commercial ELISA and IFA, respectively. Five out of 100 (5%) humans were seropositive for E. canis and E. chaffeensis. Rhipicephalus sanguineus (n = 291, 97.98%) on dogs and Amblyomma cajennense (n = 25, 96.15%) on horses were the most common ticks found. In conclusion, anti-Ehrlichia spp. antibodies were found in horses; however, the lack of a molecular characterization precludes any conclusion regarding the agent involved. Additionally, the higher seroprevalence of E. canis in dogs and the evidence of anti-Ehrlichia spp. antibodies in humans suggest that human cases of ehrlichiosis in Brazil might be caused by E. canis, or other closely related species.

Vector-borne pathogens in dogs from Costa Rica: first molecular description of Babesia vogeli and Hepatozoon canis infections with a high prevalence of monocytic ehrlichiosis and the manifestations of co-infection

Infection with canine vector-borne pathogens was evaluated in dogs from four different regions of Costa Rica by PCR. Demographic data, clinical signs, packed cell volume values, and the presence of tick infestation were recorded for each dog. Forty seven percent (69/146) of the dogs were infected with at least one pathogen and 12% were co-infected with two pathogens. Ehrlichia canis was detected in 34%, Anaplasma platys in 10%, Babesia vogeli in 8%, and Hepatozoon canis in 7.5% of the blood samples. No infection was detected with Leishmania spp. in blood, skin scrapings or conjunctival swabs. Thirty percent of the dogs presented at least one clinical sign compatible with vector-borne disease, and of those, 66% were infected with a pathogen. Subclinical infections were determined in 58% of the infected dogs including 82% (9/11), 58% (29/50), 42% (5/12) and 36% (5/14) of the dogs with H. canis, E. canis, B. vogeli and A. platys infections, respectively. A distinct relationship was found between infection and anemia. The mean PCV values were 34.4% in dogs with no infection, 31.5% in those who had a single infection and 23% in those with co-infection. Co-infected dogs had significantly lower PCV values compared to non-infected and single-infected dogs (p<0.0001). Thirty five percent (51/146) of the dogs were infested with ticks, 82% of them were infested with Rhipicephalus sanguineus sensu lato and 18% with Amblyomma ovale. Dogs infected with A. platys, B. vogeli, or E. canis were significantly associated with R. sanguineus s.l. infestation (p<0.029). This is the first description of infections with B. vogeli and H. canis in Costa Rica as well as in Central America. The results of this study indicate that multiple vector-borne pathogens responsible for severe diseases infect dogs in Costa Rica and therefore, increased owner and veterinarian awareness are needed. Moreover, prevention of tick infestation is recommended to decrease the threat of these diseases to the canine population.

Usefulness of a rapid immuno-migration test for the detection of canine monocytic ehrlichiosis in Africa

A rapid immuno-migration test for the serological detection of canine monocytic ehrlichiosis, Witness® Ehrlichia (WE) (Zoetis, France), was evaluated in 528 serum samples from dogs living in endemic areas of West and East Africa: Senegal (N=208), Ivory Coast (N=7), Sudan (N=27), and Djibouti (N=286). Of these dogs, 200 were French military working dogs (MWD) temporarily residing in Africa. The WE test results were compared with those obtained by indirect immunofluorescence (IFA). The sensitivity of WE was 97% [94.2, 98.7] with a specificity of 100% [98.6, 100]. In MWD, the seroprevalence (IFA) was 7%; in native dogs, it reached 77.1%. This significant difference can be explained by prophylactic measures from which MWD benefit. The WE test represents a simple, fast and reliable test for the detection of anti-Ehrlichia canis antibodies. Its implementation for the diagnosis of clinical cases has been validated in the field, and its use allows easy detection of asymptomatic dogs that may be carriers of E. canis.

Study of ehrlichiosis in kennel dogs under treatment and prevention during seven months in Dakar (Senegal)

In Dakar kennels where morbidity and mortality attributed to diseases transmitted by ticks were high, we conducted a field study to assess the prevalence of Ehrlichia canis, Anaplasma platys and Babesia spp. infections in two kennels (n = 34 dogs) and to study the impact of tick protection. The first day of the study, the E. canis PCR were positive in 18 dogs (53%). A. platys was found in one dog and all dogs were negative for Babesia spp. After one month of doxycycline treatment, the number of PCR positive dogs decreased significantly to 2 (5.9%). During seven months, all dogs were treated monthly topically with a novel combination (Certifect(®), Merial) delivering at least 6.7 mg fipronil/kg body weight, 8.0mg amitraz/kg and 6 mg (S)-methoprene/kg. The number of PCR positive dogs remained stable all over the seven months, with 4 dogs being positive at Day 90 and 2 at Day 210. The combination of treatment and monthly prevention had a significant effect in the two kennels. All dogs remained healthy, which was not the case in previous years.

Ehrlichia canis infection in a dog with no history of travel outside the United Kingdom

A two-year-old female neutered Tibetan terrier was referred following a one-month history of lethargy, inappetence and pancytopenia, which had been poorly responsive to immunosuppressive and fluoroquinolone treatment. The dog was diagnosed with pure red cell aplasia and was found to be positive for Ehrlichia canis by both antibody titre measurement and polymerase chain reaction. The dog lived in London and had not travelled outside the UK. The dog was treated with doxycycline, prednisolone and ciclosporin, but died as a result of gastrointestinal tract haemorrhage. To the authors' knowledge, this represents the first reported case of Ehrlichia canis in a dog in the UK with no previous travel history.

Are vector-borne pathogen co-infections complicating the clinical presentation in dogs?

Background

Infection by two or more canine vector-borne disease (CVBD)-causing pathogens is common in subtropical and tropical regions where vectors are plentiful. Co-infections may potentiate disease pathogenesis, thereby altering clinical manifestations typically associated with singular infections. These factors complicate diagnosis, treatment and can adversely influence prognosis if the practitioner fails to suspect, document, and treat each concurrent infection. The spectrum of pathogens co-infecting dogs may change over time in a given practice location due to the rapid expansion of arthropods and their associated vectored agents, and international transit among pets and wild animals. This applies, for example, to Dirofilaria immitis and Leishmania infantum, the distributions of which have expanded from northern to southern Italy, and vice versa, respectively. Indeed, mixed infections by D. immitis and L. infantum have only been reported once in Italy, probably due to the fact that competent vectors for these infections do not usually occur in the same geographical areas. Thus, information that would help practitioners to identify clinical presentations in dogs co-infected by D. immitis and L. infantum and other CVBD-causing pathogens is scant.

Findings

This manuscript describes the clinical history and physical examination of findings for 7 CVBD co-infected dogs that were examined because of a spectrum of clinical signs. Five dogs were co-infected with L. infantum and Ehrlichia canis, one dog with L. infantum, E. canis and D. immitis and the remaining dog with L. infantum and D. immitis.

Conclusions

The clinical signs and haematological abnormalities associated with the diagnostic evaluation and treatment of these dogs is discussed. Also, the usefulness of bone marrow specimens for the molecular diagnosis of CVBDs and for the enhanced monitoring of treatment response is emphasized.

Arthropod-borne infections in travelled dogs in Europe

Pet animal movement is ever increasing within the European Union and in that context canine vectorborne infections gained a considerable importance. Information on these infections in travelled dogs is nevertheless limited. A first prospective study on vector-borne infections was conducted in 106 dogs travelling from Germany to countries in South and South-East Europe. The dogs were screened prior to and consecutively up to three times after travel by haematological (Giemsa-stained buffy coat smears, Knott’s-Test), molecular biological (PCR) as well as serological (IFAT, DiroChek^®-ELISA) methods for arthropod-borne infections. Seven animals were seropositive for antibodies against Babesia canis sspp., Leishmania spp. and/or Ehrlichia canis prior to travel to Italy, Spain, France, Croatia, Greece, or Hungary. In the consecutive screening after return there was no increase in the number of seropositive dogs. None was positive in direct methods. The mean duration of the stay was 17 days and 51% of the dogs were prophylactically treated with ectoparasiticidal formulations. Preliminary data from this study on canine vector-borne infections indicate a low risk for infection during a limited single stay in endemic countries.

Molecular detection of Ehrlichia canisin dogs from the Pantanal of Mato Grosso State, Brazil

The present study evaluated the presence of EhrlichiaDNA in the blood samples of 320 dogs from the urban and rural areas of the municipality of Poconé, Pantanal region, Mato Grosso state, by Polymerase Chain Reaction (PCR), targeting the ehrlichial dsbgene. Risk factors for infection in dogs were also evaluated. Forty-eight (15%, 95% CI: 11.4-19.5%) dogs were positive: 25 (15.6%, 95% CI: 10.4-22.2%) from the urban area and 23 (14.4%, 95% CI: 9.3-20.8%) from the rural area (P > 0.05). Partial DNA sequence obtained from PCR products of 18 samples from the urban area and 16 samples from the rural area were 100% identical to E. canis from Brazil and the USA. This study reports the first E. canis molecular detection in dogs from the northern Pantanal region.

Tick-borne pathogens and disease in dogs on St. Kitts, West Indies

Between 2009 and 2011, we conducted a case-control study of ticks and tick-associated pathogens affecting dogs on the island of St. Kitts, eastern Caribbean, including 55 cases of clinically suspected tick-borne disease (TBD) and 110 presumably healthy animals presented for elective surgeries. Rhipicephalus sanguineus caused year-round infestations of dogs, and 36% of the dogs in the study were infested at the time of examination. Overall, 62% of suspected TBD cases and 24% of presumably healthy dogs tested positive by PCR for infections with: Anaplasma platys (0% and 4%), Babesia canis vogeli (20% and 6%), Babesia gibsoni (18% and 5%), Ehrlichia canis (35% and 7%), and Hepatozoon canis (5% and 2%). Co-infections were documented in 15% of these PCR-positive dogs. Antibodies against A. platys or E. canis were noted in 36% of the dogs. Thrombocytopenia was the most common sign of infection, followed by anemia. This is the first detection of A. platys, B. canis vogeli, or H. canis on St. Kitts and the first detection of B. gibsoni in the Caribbean. We conclude that tick-borne pathogens of dogs are highly prevalent in this region and may present in dogs that appear healthy, in spite of hematologic abnormalities that may increase surgical risk.

Ehrlichiosis, babesiosis, anaplasmosis and hepatozoonosis in dogs from St. Kitts, West Indies

Background

Although tick-borne diseases are important causes of morbidity and mortality in dogs in tropical areas, there is little information on the agents causing these infections in the Caribbean.

Methodology

We used PCRs to test blood from a cross-section of dogs on St Kitts for Ehrlichia (E.) canis, Babesia (B.) spp., Anaplasma (A.) spp. and Hepatozoon (H.) spp. Antibodies against E. canis and A. phagocytophilum/platys were detected using commercial immunochromatography tests. Records of the dogs were examined retrospectively to obtain clinical and laboratory data.

Principal findings

There was serological and/or PCR evidence of infections of dogs with E. canis (27%; 46/170), Babesia spp. (24%; 90/372) including B. canis vogeli (12%; 43/372) and B. gibsoni (10%; 36/372), A. platys (11%; 17/157) and H. canis (6%; 15/266). We could not identify the Babesia sp. detected in nine dogs. There was evidence of multiple infections with dual infections with E. canis and B. canis vogeli (8%; 14/179) or B. gibsoni (7%; 11/170) being the most common. There was agreement between immunochromatography and PCR test results for E. canis for 87% of dogs. Only 13% of exposed dogs had signs of a tick-borne disease and 38% had laboratory abnormalities. All 10 dogs presenting for a recheck after treatment of E. canis with doxycycline were apparently healthy although all remained seropositive and six still had laboratory abnormalities despite an average of two treatments with the most recent being around 12 months previously. Infections with Babesia spp. were also mainly subclinical with only 6% (4/67) showing clinical signs and 13% (9/67) having laboratory abnormalities. Similarly, animals with evidence of infections with A. platys and H. canis were largely apparently healthy with only occasional laboratory abnormalities.

Conclusions

Dogs are commonly infected with tick-borne pathogens in the Caribbean with most having no clinical signs or laboratory abnormalities.

Molecular detection of Ehrlichia canis in dogs in Malaysia

An epidemiological study of Ehrlichia canis infection in dogs in Peninsular Malaysia was carried out using molecular detection techniques. A total of 500 canine blood samples were collected from veterinary clinics and dog shelters. Molecular screening by polymerase chain reaction (PCR) was performed using genus-specific primers followed by PCR using E. canis species-specific primers. Ten out of 500 dogs were positive for E. canis. A phylogenetic analysis of the E. canis Malaysia strain showed that it was grouped tightly with other E. canis strains from different geographic regions. The present study revealed for the first time, the presence of genetically confirmed E. canis with a prevalence rate of 2.0% in naturally infected dogs in Malaysia.

Canine vector-borne diseases are a worldwide concern particularly in the tropics and sub-tropics that provide favourable climatic conditions for the vectors. Malaysia, a tropical paradise, is thus home to a wide range of vectors as well as the pathogens that they harbor. Ehrlichia canis, a ubiquitous tick-borne pathogen of dogs, is the causative agent of canine monocytic ehrlichiosis, the most common clinically significant tick-borne disease of dogs in Malaysia. The pet explosion coupled with the increasing number of stray dogs, has resulted in a surge in vector-borne diseases in companion animals in Southeast Asia. Despite this, there is very little published information regarding this subject in Malaysia. There are only two published studies on E.canis in Peninsular Malaysia based on traditional light microscopic detection and antibody detection techniques. This disease has been notoriously difficult to diagnose based on the traditional methods. This research investigates this important disease of canids using molecular techniques for the first time in Malaysia providing a more accurate picture of its presence and prevalence in the country.

Seroprevalence of tick-borne infections in military working dogs in the Republic of Korea

In this study we endeavored to determine the seroprevalence of tick-borne infections in the military working dog (MWD) population in the Republic of Korea (ROK). Our sample population consisted of 182 serum samples from MWDs for 3 different years (1996, 2002, and 2007). In addition, 63 whole blood samples from 2007 were available for polymerase chain reaction (PCR). Serum samples were evaluated by a commercially available enzyme-linked immunosorbent assay (ELISA) and immunofluorescence assay (IFA) for Ehrlichia canis and Anaplasma phagocytophilum, and by ELISA only for Borrelia burgdorferi. PCR amplification of DNA was performed to screen for Ehrlichia canis, E. chaffeensis, E. ewingii, Anaplasma phagocytophilum, A. platys, Borrelia burgdorferi, and Rickettsia rickettsii, as well as Babesia and Theileria species using previously published primers and probes. A total of 56 (30.8%) MWDs were positive by at least one serologic test. Seroprevalences for Anaplasma and Ehrlichia were 4.4% and 0.6% based on the ELISA, and 24.7% and 22.5% based on the IFA, respectively. ELISA testing for Borrelia yielded 2 (1.1%) positive results. In parallel testing using both the ELISA and IFA tests, the percentages of dogs with one or more positive results were 34.1%, 25.9%, and 28.4%, for 1996, 2002, and 2007, respectively. There was no significant differences in seroprevalence based on location, year, breed, or sex of the MWD. There was poor agreement between IFA and ELISA test results. No MWD sample had a positive PCR result. MWDs stationed in Korea had serologic evidence of exposure to several tick-borne pathogens, but PCR testing did not identify any active infections.

First detection and molecular characterization of Ehrlichia canis from dogs in Nigeria

The present study aimed to detect the presence of Ehrlichia canis in naturally infected dogs in Nigeria, using a combination of PCR and sequence analysis of the 16S rRNA gene and two genes encoding the tandem repeat-containing proteins (TRPs), TRP19 and TRP36. Out of a total of 100 blood samples collected from domestic dogs presented to veterinary hospitals in Jos, the capital city of Plateau State of Nigeria, 11 were positive in nested PCR for E. canis. Sequencing results for these amplicons showed that all of the 16S rDNA sequences (1623 bp) or the TRP19 coding sequences (414 bp) were identical to each other and had very high similarities (99.3-100%) with those from other E. canis strains accessible in GenBank. The TRP36 gene sequences derived from the 11 Nigerian isolates were identical to each other except for the number of the 27-bp repeat unit in a tandem repeat region, which was found to be 8, 12 or 18. Without considering the number of tandem repeats, these sequences had 100% identity to that of the reported Cameroon 71 isolate, but distinctly differed from those obtained from other geographically distant E. canis strains previously published. A phylogenetic tree of E. canis based on the TRP36 amino acid sequences showed that the Nigerian isolates and the Cameroon 71 isolate fell into a separate clade, indicating that they may share a common ancestor. Overall, this study not only provides the first molecular evidence of E. canis infections in dogs from Nigeria but also highlights the value of the TRP36 gene as a tool to classify E. canis isolates and to elucidate their phylogeographic relationships.

An assessment of whole blood and fractions by nested PCR as a DNA source for diagnosing canine ehrlichiosis and anaplasmosis

Ehrlichiosis and anaplasmosis are tick-borne diseases. Ehrlichia canis and Anaplasma platys infect mainly white cells and platelets, respectively. The main DNA source for PCR is peripheral blood, but the potential of blood cell fractions has not been extensively investigated. This study aims at assessment of whole blood (WB) and blood fractions potential in nested PCR (nPCR) to diagnose canine ehrlichiosis and anaplasmosis. The 16S rRNA gene was amplified in 71.4, 17.8, 31.57, and 30% of the WB, granulocyte (G), mononuclear cells (M), and buffy coat (BC) samples. Compared to the WB, the sensitivity of the PCR was 42.86% for the M, and BC fractions, 21.43% for the G, and 33.33% for the blood clot (C). There was fair agreement between the WB and M, BC and C, and slight with the G. Fair agreement occurred between the nPCR and morulae in the blood smear. One animal was coinfected with A. platys and E. canis. This study provided the first evidence of A. platys infection in dogs in Paraíba, Brazil, and demonstrated that WB is a better DNA source than blood fractions to detect Ehrlichia and Anaplasma by nPCR, probably because of the plasma bacterial concentration following host cell lysis.

Haematological parameters in stray dogs seropositive and seronegative to Ehrlichia canis in North Trinidad

In view of the fact that stray dogs are a reservoir for many diseases, this study was undertaken to determine the prevalence of Ehrlichia canis in stray dogs in North Trinidad and to evaluate the diagnostic implications of haematological alterations associated with seropositivity. Overall, 41 (44.6%) of 92 stray dogs were seropositive to E. canis by the indirect immunofluorescent antibody test. Dogs, one year of age and older (59.7%) were more likely to be seropositive than dogs less than one year old (13.3%) (p<0.001). No significant differences in seropositivity between females and males were found. The odds ratios showed that seropositive dogs were 3.34 (CI 95%; 1.33-8.59) and 5.17 (CI 95%; 0.19-1.26) times more likely to have low platelet counts and elevated total serum protein concentrations (p=0.014 and p<0.001, respectively) than seronegative dogs. Lower mean platelet counts and a higher mean total protein concentration were associated with seropositivity (p<0.01). Mean eosinophil and segmented neutrophil counts were elevated in dogs that tested negative for E. canis antibodies (p=0.002 and p<0.005, respectively). Other haematological parameters were not different between the 2 groups. The high percentage of stray dogs infected with E. canis should alert veterinarians to the potential risk of transmission of the disease. A comprehensive study possibly using molecular methods such as nested PCR should be undertaken to determine how co-infection with other pathogens may alter haematological profiles. In general, control of ticks and stray dog populations may help to control the spread of tick-borne diseases.

Ehrlichia canis infection in two dogs that emigrated from endemic areas

Two dogs, emigrated from Zambia and China to Japan, were diagnosed with Ehrlichia canis infection. Both cases had thrombocytopenia, non-regenerative anemia, and hypergloblinemia with polyclonal gammopathy. Case 1 had ataxia of the hind limbs. Severe meningitis was revealed by magnetic resonance imaging examination. Intracytoplasmic inclusions were observed in mononuclear cells of cerebrospinal fluid. Case 2 had a history of bilateral epistaxis, and severe pancytopenia was noticed in complete blood count. Diagnosis was finally achieved by nested polymerase chain reaction and sequence analysis. Thus, even in non-endemic areas, E. canis infection should be included in the differential diagnosis of clinically ill dogs that emigrated from endemic areas.

A survey of canine tick-borne diseases in India

Background

There are few published reports on canine Babesia, Ehrlichia, Anaplasma, Hepatozoon and haemotropic Mycoplasma infections in India and most describe clinical disease in individual dogs, diagnosed by morphological observation of the microorganisms in stained blood smears. This study investigated the occurrence and distribution of canine tick-borne disease (TBD) pathogens using a combination of conventional and molecular diagnostic techniques in four cities in India.

Results

On microscopy examination, only Hepatozoon gamonts were observed in twelve out of 525 (2.3%; 95% CI: 1.2, 4) blood smears. Using polymerase chain reaction (PCR), a total of 261 from 525 dogs (49.7%; 95% CI: 45.4, 54.1) in this study were infected with one or more canine tick-borne pathogen. Hepatozoon canis (30%; 95% CI: 26.0, 34.0) was the most common TBD pathogen found infecting dogs in India followed by Ehrlichia canis (20.6%; 95% CI: 17.2, 24.3), Mycoplasma haemocanis (12.2%; 95% CI: 9.5, 15.3), Anaplasma platys (6.5%; 95% CI: 4.5, 8.9), Babesia vogeli (5.5%, 95% CI: 3.7, 7.8) and Babesia gibsoni (0.2%, 95% CI: 0.01, 1.06). Concurrent infection with more than one TBD pathogen occurred in 39% of cases. Potential tick vectors, Rhipicephalus (most commonly) and/or Haemaphysalis ticks were found on 278 (53%) of dogs examined.

Conclusions

At least 6 species of canine tick-borne pathogens are present in India. Hepatozoon canis was the most common pathogen and ticks belonging to the genus Rhipicephalus were encountered most frequently. Polymerase chain reaction was more sensitive in detecting circulating pathogens compared with peripheral blood smear examination. As co-infections with canine TBD pathogens were common, Indian veterinary practitioners should be cognisant that the discovery of one such pathogen raises the potential for multiple infections which may warrant different clinical management strategies.

"Candidatus Neoehrlichia mikurensis" infection in a dog from Germany

"Candidatus Neoehrlichia mikurensis" is a new intracellular pathogen associated with human infection and death. "Candidatus Neoehrlichia mikurensis" infection in a chronically neutropenic dog from Germany was confirmed by DNA sequencing. The same organism was previously described from ticks and two sick human beings from Germany.

Ehrlichiosis and anaplasmosis in dogs and cats

In the time since canine ehrlichiosis due to Ehrlichia canis was first described in 1935 and first recognized in the United States in 1962, many key advances have been made in our understanding of the diversity of the rickettsial organisms responsible for ehrlichiosis and anaplasmosis in dogs and, occasionally, cats, the vectors capable of transmitting these agents, and the role these organisms play as both important veterinary pathogens and zoonotic disease agents. Despite considerable progress in the field, much remains to be learned regarding mechanisms contributing to pathogenesis, effective treatment modalities, and prevention strategies that best protect pet health. This article highlights current understanding of the transmission, diagnosis, and management of ehrlichiosis and anaplasmosis in dogs and cats.