Soroprevalência de Ehrlichia canis em cães de abrigos e associações de proteção, do oeste do Paraná, Brasil / Soroprevalence of Ehrlichia canis in dogs from shelters and protection associations in western Paraná, Brazil / Soroprevalencia de Ehrlichia canis en perros de refugios y asociaciones de protección, del oeste de Paraná, Brasil

A erliquiose é uma doença riquetsial infecciosa causada por uma bactéria, pertencente ao gênero Ehrlichia, muito comum em cães e considerada uma importante hemoparasitose. Devido sua relevância na população canina e fácil transmissão por meio de carrapatos, mostra-se necessário conhecer melhor os aspectos epidemiológicos desta doença. Este estudo teve como objetivo avaliar a prevalência de Ehrlichia canis e os aspectos hematológicos em cães de abrigos temporários, de associações de proteção aos animais abandonados, nos municípios de Palotina e Guaíra, no Paraná. No total, 60 cães foram submetidos à coleta de amostras sanguíneas, para realização de hemograma e imunoflourescência indireta para detecção dos anticorpos anti-E. canis. A prevalência encontrada foi de 60% (36/60), não houve correlação positiva com relação ao sexo dos animais, presença de carrapatos ou trombocitopenia. Os dados revelam uma alta prevalência desta doença parasitária em cães de abrigos e a necessidade do estabelecimento de medidas de controle dos agentes transmissores.(AU)

Ehrlichiosis is an infectious ricketsial disease caused by bacteria belonging to the Ehrlichia genus. It is very common in dogs and is considered as an important hemoparasitosis. Due to its relevance in the canine population and its easy transmission through ticks, it is necessary to further understand the epidemiological aspects of the disease. This study aimed at evaluating the prevalence of Ehrlichia canis and the hematological aspects in dogs from temporary shelters and associations for the protection of abandoned animals in the cities of Palotina and Guaíra, in the state of Paraná. Blood samples were collected from 60 dogs for blood count and indirect immunofluorescence testing, and detection of anti-E. canis antibodies. A prevalence of 60% (36/60) was found, with no positive correlation regarding the gender of the animals, presence of ticks, or thrombocytopenia. The data reveal a high prevalence of this parasitic disease in shelter dogs and the need to establish control measures related to the transmitting agents.(AU)

Ehrlichiosis es una enfermedad ricketsial infecciosa causada por una bacteria perteneciente al género Ehrlichia, muy frecuente en perros y considerada una importante hemoparasitaria. Debido a su relevancia en la población canina y fácil transmisión a través de garrapatas, es necesario conocer mejor los aspectos epidemiológicos de esta enfermedad. Este estudio tenía como objetivo evaluar la prevalencia de Ehrlichia canis, así como los aspectos hematológicos para la protección de animales abandonados en los municipios de Palotina y Guaíra, Paraná. Un total de 60 perros fueron sometidos a muestras de sangre para el recuento sanguíneo y la inmunoflourescencia indirecta detección de anticuerpos anti-E canis. La prevalencia encontrada fue del 60% (36/60), sin correlación positiva con la el sexo de los animales, la presencia de garrapatas o trombocitopenia. Los datos revelan una alta prevalencia de esta enfermedad parasitaria en perros refugio y la necesidad de establecer medidas de control para los agentes transmisores.(AU)

Exposure of client-owned cats to zoonotic vector-borne pathogens: Clinic-pathological alterations and infection risk analysis.

Zoonotic Vector-Borne Diseases (VBDs) represent a relevant health issue for pets and humans. Italy is a major epidemiological hub for feline VBDs, because of suitable conditions for vector biology and disease transmission patterns. The present study investigated the exposure to major zoonotic arthropod-borne pathogens of cats in Italy, along with the evaluation of clinic-pathological features and a risk factor analysis. Out of 167 examined cats, 52 (31.1%) were seropositive for at least one vector-borne pathogen, being positivity for Bartonella henselae the most recorded (18%). Also, various cats seroreacted for Rickettsia felis (10.8%) and Rickettisa typhi (4.2%), Leishmania infantum (3%), Anaplasma phagocytophilum (2.4%) and Ehrlichia canis (2.4%). Forty-six cats were tested also for antibodies against D. immitis and two (4.3%) scored positive. The statistical analysis showed a positive association between flea infestation and seropositivity to B. henselae, other than an association between the administration of monthly ectoparasiticide treatments and seronegativity for Rickettsia spp.; seropositive cats were older than negative animals and the lifestyle (i.e. indoor vs outdoor) was not correlated with exposure to vector-borne pathogens. The majority of seropositive cats appeared clinically healthy or showed aspecific clinical signs. Around 80% of seropositive cats had one or more biochemical and/or complete blood count abnormalities. The present data confirm the endemicity of zoonotic feline VBDs in Italy and indicate that awareness on arthropod infections and transmitted pathogens should be kept high and possible implemented, towards the protection of animal and human health with adequate surveillance plans.

Molecular detection and characterization of Anaplasma platys and Ehrlichia canis in dogs from northern Colombia.

Ehrlichia canis and Anaplasma platys are intracellular tick-transmitted bacteria that infect dogs; there is evidence for limited zoonotic potential as well. The prevalence of E. canis in Colombia has been evaluated in different regions; however little is known about the prevalence or distribution of A. platys. Neither pathogen has been studied in the Magdalena region, thus the purpose of our study was to assess the prevalence of these pathogens in dogs attending veterinary clinics from the cities of Santa Marta and Ciénaga, and to assess possible associated risk factors for infection. A. platys and E. canis infections in blood were evaluated by Taqman PCR assays. E. canis was detected in 26/170 (15.3%, 95% CI 10.4%-21.8%) and A. platys in 34/168 (20.2%, 95% CI 14.6%-27.3%) of all dogs tested. Eleven dogs (6.5%, 95% CI 3.4-11.7%) were coinfected with both pathogens. Sequencing results showed low diversity within E. canis and within A. platys strains, however a strain of E. canis detected in our study area is genetically distinct from strains reported in another city of Colombia. Our results suggest that for A. platys, Santa Marta dogs were at greater risk than Ciénaga dogs, and that purebred dogs were at slightly lower risk in both areas. The confirmation of these pathogens in northern Colombia should cause concern for the possible co-transmission of these agents to humans or animals in the region.

Does co-infection with vector-borne pathogens play a role in clinical canine leishmaniosis?

BACKGROUND: The severity of canine leishmaniosis (CanL) due to Leishmania infantum might be affected by other vector-borne organisms that mimic its clinical signs and clinicopathological abnormalities. The aim of this study was to determine co-infections with other vector-borne pathogens based on serological and molecular techniques in dogs with clinical leishmaniosis living in Spain and to associate them with clinical signs and clinicopathological abnormalities as well as disease severity. METHODS: Sixty-one dogs with clinical leishmaniosis and 16 apparently healthy dogs were tested for Rickettsia conorii, Ehrlichia canis, Anaplasma phagocytophilum and Bartonella henselae antigens by the immunofluorescence antibody test (IFAT) and for E. canis, Anaplasma spp., Hepatozoon spp., Babesia spp. and filarioid DNA by polymerase chain reaction (PCR). RESULTS: Among the dogs examined by IFAT, the seroprevalences were: 69% for R. conorii, 57% for E. canis, 44% for A. phagocytophilum and 37% for B. henselae; while the prevalences found by PCR were: 8% for Ehrlichia/Anaplasma, 3% for Anaplasma platys and 1% for H. canis. No other pathogen DNA was detected. Statistical association was found between dogs with clinical leishmaniosis and seroreactivity to R. conorii antigen (Fisher's exact test: P = 0.025, OR = 4.1, 95% CI = 1-17) and A. phagocytophilum antigen (Fisher's exact test: P = 0.002, OR = 14.3, 95% CI = 2-626) and being positive to more than one serological or molecular tests (co-infections) (Mann-Whitney test: U = 243, Z = -2.6, n 1 = 14, n 2 = 61, P = 0.01) when compared with healthy dogs. Interestingly, a statistical association was found between the presence of R. conorii, E. canis, A. phagocytophilum and B. henselae antibodies in sick dogs and some clinicopathological abnormalities such as albumin and albumin/globulin ratio decrease and increase in serum globulins. Furthermore, seroreactivity with A. phagocytophilum antigens was statistically associated with CanL clinical stages III and IV. CONCLUSIONS: This study demonstrates that dogs with clinical leishmaniosis from Catalonia (Spain) have a higher rate of co-infections with other vector-borne pathogens when compared with healthy controls. Furthermore, positivity to some vector-borne pathogens was associated with more marked clinicopathological abnormalities as well as disease severity with CanL.

Molecular detection of Anaplasma bovis, Ehrlichia canis and Hepatozoon felis in cats from Luanda, Angola.

BACKGROUND: Molecular identification of tick-borne pathogen infection in cats from Africa is scarce. The presence of bacterial (Anaplasma and Ehrlichia) and protozoal (Babesia and Hepatozoon) agents was investigated in blood samples from 102 domestic cats from Luanda, Angola, by polymerase chain reaction and DNA sequencing. RESULTS: Three cats (2.9%) were found infected with Ehrlichia canis, three (2.9%) with Hepatozoon felis and one (1.0%) with Anaplasma bovis. The prevalence of infections with one single agent was 4.9%, and that of infection with two agents (i.e. E. canis and H. felis) was 1.0%. In total, six cats (5.9%) were found infected with at least one of the detected tick-borne agents. CONCLUSIONS: This is the first report of A. bovis, E. canis and H. felis in cats from Angola. To the best of our knowledge, A. bovis is also being reported for the first time in domestic cats outside of Japan. Cats are at a low to moderate risk of being infected with tick-borne agents in Luanda.

Investigação molecular de Ehrlichia canis, Anaplasma platys, Anaplasma phagocytophilum e Rickettsia spp. em felídeos selvagens cativos / Molecular investigation of Ehrlichia canis, Anaplasma platys, Anaplasma phagocytophilum and Rickettsia spp. in captive wild felids

Doenças transmitidas por vetores estão emergindo e reemergindo em todo o mundo, representando um desafio na medicina humana e veterinária. Entre essas doenças estão aquelas causadas pelos agentes da ordem das Rickettsiales, que são bactérias Gram-negativas intracelulares obrigatórias, com capacidade de infectar vários animais e seres humanos. As Rickettsiales das espécies Ehrlichia spp. e Anaplasma spp. são observadas em vacúolos citoplasmáticos de leucócitos e plaquetas. As Rickettsiales da espécie Rickettsia spp. infectam livremente citoplasma ou núcleo de células hospedeiras. O objetivo do presente estudo foi investigar a infecção natural por Ehrlichia canis, Anaplasma platys, Anaplasma phagocytophilum e Rickettsia spp. em felídeos selvagens cativos no Distrito Federal e Goiás, Brasil. Além disso, também objetivou-se relacionar possíveis alterações hematológicas decorrentes da presença desses agentes. Amostras de sangue de 34 animais foram analisadas por meio da PCR para detecção de presença de DNA desses agentes. O DNA de Ehrlichia canis foi detectado em 5,8% (2/34) das amostras, A. platys foi detectado 64,7% (22/34), A. phagocytophilum foi detectado em 5,8% (2/34). O DNA de Rickettsia spp. não foi detectado em nenhuma amostra. Dois felídeos apresentaram coinfecção por E. canis e A. platys e dois apresentaram coinfecção por A. platys e A. phagocytophilum. Não houve diferenças significativas nos dados hematológicos das amostras positivas e negativas. Os dados sugerem que os felídeos selvagens cativos podem servir como potenciais reservatórios para Ehrlichia spp. e Anaplasma spp., a despeito de não ocasionarem alterações hematológicas.(AU)

Vector-borne diseases have been emerging and reemerging all over the world, causing a challenge to veterinary and human medicine. Among these diseases are those caused by agents of the order Rickettsiales, obligatory intracellular Gram-negative bacteria, with ability to infect several animals and humans. Rickettsiales of the species Ehrlichia spp. and Anaplasma spp. residing in cytoplasmic vacuoles of leukocytes and platelets. Rickettsiales of the species Rickettsia spp. freely infect cytoplasm or nucleus of host cells. The aim of the present study was to investigate the natural infection with Ehrlichia canis, Anaplasma platys, Anaplasma phagocytophilum and Rickettsia spp. in captive wild felids at the Federal District and Goiás, Brazil. In addition, it was also aimed to relate possible changes in hemogram with the presence of these agents. Blood samples from 34 animals were analyzed by PCR to detect the presence of DNA from these agents. The DNA of Ehrlichia canis was detected in 5.8% (2/34) of samples. A. platys was detected in 64.7% (22/34), A. phagocytophilum was detected in 5.8% (2/34). The DNA of Rickettsia spp. was not detected in any sample. Two felides presented co-infection with E. canis and A. platys, and two presented co-infection with A. platys and A. phagocytophilum. There were no significant differences in hematological data from positive and negative samples. The data suggest that captive wild felids can serve as potential reservoirs for Ehrlichia spp. and Anaplasma spp., despite hematological abnormalities were not observed.(AU)

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.

Development and evaluation of a loop-mediated isothermal amplification assay for detection of Ehrlichia canis DNA in naturally infected dogs using the p30 gene.

Canine monocytic ehrlichiosis (CME) is a common tick-borne disease caused by the rickettsial bacterium Ehrlichia canis (Rickettsiales: Anaplasmataceae). In view of the different stages and variable clinical signs of CME, which can overlap with those of other infections, a conclusive diagnosis can more readily be obtained by combining clinical and hematological evaluations with molecular diagnostic methods. In this study, a loop-mediated isothermal amplification (LAMP) assay targeting the p30 gene of E. canis was developed. The assay was developed using DNA extracted from E. canis-infected cultures of the macrophage cell line DH82 and samples from dogs testing positive for E. canis DNA by PCR. The LAMP assay was compared to a p30-based PCR assay, using DNA extracted from EDTA-anticoagulated blood samples of 137 dogs from an endemic region in Brazil. The LAMP assay was sensitive enough to detect a single copy of the target gene, and identified 74 (54.0%) E. canis DNA-positive samples, while the p30 PCR assay detected 50 positive samples (36.5%) among the field samples. Agreement between the two assays was observed in 42 positive and 55 negative samples. However, 32 positive samples that were not detected by the PCR assay were identified by the LAMP assay, while eight samples identified as E. canis-positive by PCR showed negative results in LAMP. The developed E. canis LAMP assay showed the potential to maximize the use of nucleic acid tests in a veterinary clinical laboratory, and to improve the diagnosis of CME.

Influence of experimental canine ehrlichiosis on the E-ADA activity and purine levels in serum and possible functional correlations with pathogenesis.

The aim of this study was to evaluate adenosine deaminase activity and purines levels in serum of dogs experimentally infected by Ehrlichia canis. Banked serum samples of dogs divided into two groups with five animals each: healthy animals and animals infected by E. canis. The concentration of purines (adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), adenosine, inosine, hypoxanthine, xanthine and uric acid), and adenosine deaminase (E-ADA) activity in sera were evaluated. Samples were collected on days 12 and 30 post-infection (PI). The E-ADA activity showed a significant reduction on day 12 PI, and increased on day 30 PI in dogs infected with E. canis. On day 12, an increase in seric concentration of ATP, ADP and adenosine was verified, and different levels of hypoxanthine, xanthine and uric acid had a drastic reduction in infected compared healthy dogs (P<0.05). However, on day 30 PI, the levels of seric ADP and AMP decreased, unlike the concentration of xanthine and uric acid that increased significantly in infected dogs (P<0.05). Therefore, the activity of E-ADA and purine levels are altered in experimental canine ehrlichiosis, probably with the purpose of modulating the pathogenesis of the disease related to immune response, oxidative stress and coagulation disorders in acute phase.

Occurrence of Ehrlichia canis and Anaplasma platys in household dogs from northern Parana / Ocorrência de Ehrlichia canis e Anaplasma platys em cães domiciliados da região norte do Paraná

Canine monocytic ehrlichiosis caused primarily by Ehrlichia canis and canine thrombocytic anaplasmosis induced by Anaplasma platys are important emerging zoonotic tick-borne diseases of dogs. There is evidence that these pathogens can also affect humans. This study evaluated the presence of E. canis and A. platys in blood samples collected from 256 domiciled dogs in the municipality of Jataizinho, located in north region of the State of Parana, Brazil, by PCR assay. The occurrence of E. canis and A. platys was 16.4% (42/256) and 19.4% (49/256), respectively; while 5.47% (14/256) of the dogs evaluated were co-infected by these two organisms. The presence of E. canis and A. platys was not significantly associated with the variables evaluated (sex, age, outdoor access, and presence of ticks during blood collection). Infection of dogs by E. canis was associated with anemia and thrombocytopenia, while infection induced by A. platys was related only to thrombocytopenia. Canine monocytic ehrlichiosis and canine thrombocytic anaplasmosis should be included in the differential diagnoses when these hematological alterations are observed during routine laboratory evaluation of dogs.(AU)

Erliquiose monocítica canina, causada principalmente por Ehrlichia canis, e anaplasmose trombocítica canina, devida a infecção com Anaplasma platys, são importantes doenças transmitidas por carrapatos que acometem os cães, com evidências que podem também acometer o homem. O presente estudo avaliou a ocorrência desses agentes em amostras de sangue de 256 cães domiciliados na cidade de Jataizinho, na região Norte do Paraná, Brasil, utilizando a técnica da Reação em Cadeia da Polimerase (PCR). A ocorrência de E. canis e A. platys foi de 16,4% (42/256) e 19,4% (49/256), respectivamente, com 5,47% (14/256) dos animais apresentando coinfecção. Não foi observada associação significativa com as variáveis sexo, idade, acesso à rua e presença de carrapatos no momento da coleta de sangue. A infecção por E. canis teve relação com anemia e com trombocitopenia, enquanto a infecção por A. platys apresentou relação apenas com trombocitopenia. Com base nos resultados obtidos, reforçou-se a necessidade de que erliquiose e anaplasmose canina devem estar entre os diagnósticos diferenciais, quando da detecção de anemia e trombocitopenia em exames laboratoriais.(AU)

Evaluation of an attenuated strain of Ehrlichia canis as a vaccine for canine monocytic ehrlichiosis.

Canine monocytic ehrlichiosis is an important tick-borne disease worldwide. No commercial vaccine for the disease is currently available and tick control is the main preventive measure against the disease. The aim of this study was to evaluate the potential of a multi-passaged attenuated strain of Ehrlichia canis to serve as a vaccine for canine monocytic ehrlichiosis, and to assess the use of azithromycin in the treatment of acute ehrlichiosis. Twelve beagle dogs were divided into 3 groups of 4 dogs. Groups 1 and 2 were inoculated (vaccinated) with an attenuated strain of E. canis (#611A) twice or once, respectively. The third group consisted of naïve dogs which served as controls. All 3 groups were challenged with a wild virulent strain of E. canis by administering infected dog-blood intravenously. Transient thrombocytopenia was the only hematological abnormality observed following inoculation of dogs with the attenuated strain. Challenge with the virulent strain resulted in severe disease in all 4 control dogs while only 3 of 8 vaccinated dogs presented mild transient fever. Furthermore, the mean blood rickettsial load was significantly higher in the control group (27-92-folds higher during days 14-19 post challenge with the wild the strain) as compared to the vaccinated dogs. The use of azithromycin was assessed as a therapeutic agent for the acute disease. Four days treatment resulted in further deterioration of the clinical condition of the dogs. Molecular comparison of 4 genes known to express immunoreactive proteins and virulence factors (p30, gp19, VirB4 and VirB9) between the attenuated strain and the challenge wild strain revealed no genetic differences between the strains. The results of this study indicate that the attenuated E. canis strain may serve as an effective and secure future vaccine for canine ehrlichiosis.

Canine vector-borne disease pathogens in dogs from south-east Queensland and north-east Northern Territory.

OBJECTIVES: To determine the prevalence of canine vector-borne diseases (CVBD: Babesia spp., Anaplasma spp., Ehrlichia spp., haemotropic mycoplasmas and Hepatozoon) in Australian dogs; namely, dogs from pounds in south-east Queensland and an indigenous Aboriginal community in the north-east of the Northern Territory. DESIGN AND PROCEDURE: Blood samples were collected from 100 pound dogs and 130 Aboriginal community dogs and screened for the CVBD pathogens using polymerase chain reaction (PCR). All positive PCR products were sequenced for species confirmation. RESULTS: In total, 3 pound dogs and 64 Aboriginal community dogs were infected with at least one CVBD pathogen. Overall, B. vogeli was detected in 13 dogs, A. platys in 49, M. haemocanis in 23, Candidatus Mycoplasma haematoparvum in 3 and C. M. haemobos in 1 dog. Co-infections were detected in 22 Aboriginal community dogs. CONCLUSIONS: This study found B. vogeli, A. platys and haemotropic mycoplasma infections to be common in dogs in subtropical and tropical areas of Australia. This study also reports for the first time the prevalence and genetic characterisation of haemotropic mycoplasmas in dogs in Australia.

Contact with domestic dogs increases pathogen exposure in endangered African wild dogs (Lycaon pictus).

BACKGROUND: Infectious diseases have contributed to the decline and local extinction of several wildlife species, including African wild dogs (Lycaon pictus). Mitigating such disease threats is challenging, partly because uncertainty about disease dynamics makes it difficult to identify the best management approaches. Serious impacts on susceptible populations most frequently occur when generalist pathogens are maintained within populations of abundant (often domestic) "reservoir" hosts, and spill over into less abundant host species. If this is the case, disease control directed at the reservoir host might be most appropriate. However, pathogen transmission within threatened host populations may also be important, and may not be controllable by managing another host species. METHODOLOGY/PRINCIPAL FINDINGS: We investigated interspecific and intraspecific transmission routes, by comparing African wild dogs' exposure to six canine pathogens with behavioural measures of their opportunities for contact with domestic dogs and with other wild dogs. Domestic dog contact was associated with exposure to canine parvovirus, Ehrlichia canis, Neospora caninum and perhaps rabies virus, but not with exposure to canine distemper virus or canine coronavirus. Contact with other wild dogs appeared not to increase the risk of exposure to any of the pathogens. CONCLUSIONS/SIGNIFICANCE: These findings, combined with other data, suggest that management directed at domestic dogs might help to protect wild dog populations from rabies virus, but not from canine distemper virus. However, further analyses are needed to determine the management approaches--including no intervention--which are most appropriate for each pathogen.

Evolution of clinical, haematological and biochemical findings in young dogs naturally infected by vector-borne pathogens.

Longitudinal studies evaluating the evolution of clinical, haematological, biochemical findings in young dogs exposed for the first time to multiple vector-borne pathogens have not been reported. With the objective of assessing the evolution of clinical, haematological and biochemical findings, these parameters were serially monitored in naturally infected dogs throughout a 1-year follow-up period. Young dogs, infected by vector-borne pathogens based on cytology or polymerase chain reaction, were examined clinically and blood samples were obtained at seven different follow-up time points. Dogs were randomized to group A (17 dogs treated with a spot-on formulation of imidacloprid 10% and permethrin 50%) or to group B (17 dogs untreated). In addition, 10 4-month-old beagles were enrolled in each group and used as sentinel dogs. At baseline, Anaplasma platys was the most frequently detected pathogen, followed by Babesia vogeli, Bartonella spp., Ehrlichia canis and Hepatozoon canis. Co-infections with A. platys and B. vogeli, followed by E. canis and B. vogeli, A. platys and H. canis and A. platys and Bartonella spp. were also diagnosed. In dogs from group B, abnormal clinical signs were recorded at different time points throughout the study. No abnormal clinical signs were recorded in group A dogs. Thrombocytopenia was the most frequent haematological alteration recorded in A. platys-infected dogs, B. vogeli-infected dogs and in dogs co-infected with A. platys and B. vogeli or A. platys and Bartonella spp. Lymphocytosis was frequently detected among dogs infected with B. vogeli or co-infected with A. platys and B. vogeli. Beagles were often infected with a single pathogen rather than with multiple canine vector-borne pathogens. There was a significant association (p<0.01) between tick infestation and A. platys or B. vogeli, as single infections, and A. platys and B. vogeli or A. platys and Bartonella spp. co-infections. This study emphasizes the clinical difficulties associated with assigning a specific clinical sign or haematological abnormality to a particular canine vector-borne disease.

Clinical, serological, and molecular evidence of ehrlichiosis and anaplasmosis in dogs in Tunisia.

A seroepidemiological survey was conducted in five bioclimatic areas of Tunisia to determine the prevalence of antibodies to Ehrlichia canis and Anaplasma phagocytophilum antigens, surrogate markers of the agents of canine monocytic ehrlichiosis (CME) and canine granulocytic ehrlichiosis, respectively. Among 286 collected sera, 54.2% and 25.2% were seropositive for E. canis and A. phagocytophilum, respectively, by the indirect immunofluorescence antibody (IFA) test. Clinical and hematological tests were done only for 58 sick dogs from Tunis area. A reverse line blot (RLB) hybridization was then used to identify isolated Ehrlichia and Anaplasma species infecting dogs (n = 228). Among them, only two dogs were infected by A. phagocytophilum; ten sample dogs were demonstrated infected by E. canis and ten infected by Ehrlichia sp., from which one dog showed a mixed infection with A. phagocytophilum and E. canis and one with A. phagocytophilum and Ehrlichia sp. RLB findings were confirmed by sequencing; BLAST search against GenBank revealed high similarity of the sequence of Ehrlichia sp. PCR/RLB amplicons with Anaplasma platys 16S rRNA partial sequence.

Experimental Infections in dogs with Ehrlichia canis strain Borgo 89.

This study attemps to clarify the virulence and the pathogenicity of the Borgo 89 strain of Ehrlichia canis isolated from a sick dog in Corsica (France). Four unscathed beagles were intravenously injected with an inoculum of leukocytes infected with the Borgo 89 strain and the animals were examined daily for clinical signs of disease, and blood samples were drawn at frequent intervals for biochemical and hematologic assessment. Serologic (IFI) and PCR assays were also carried out. The results at autopsy are presented in this paper, leading to the conclusion that the Borgo 89 strain has a pathogenicity comparable to that of the known strains. However, the discovery of a case of completely unapparent infection raises the question of a possible individual immunization whose origin remains unexplained.

Cytokine gene expression by peripheral blood leukocytes in dogs experimentally infected with a new virulent strain of Ehrlichia canis.

Ehrlichia canis (E. canis) is a lipopolysaccharide (LPS)-deficient obligatory intracellular bacterium that causes canine monocytic ehrlichiosis, a chronic febrile disease accompanied with hematological abnormality. This study analyzed temporal expression levels of IL-1beta, IL-2, IL-6, IL-8, IFN-gamma, and TNF-alpha mRNA by peripheral blood leukocytes from dogs experimentally infected with a new virulent strain of E. canis by using real-time RT-PCR. Relative levels of IL-1beta and IL-8 transcripts normalized by the beta-actin transcript levels, were significantly upregulated, whereas those of TNF-alpha and IFN-gamma transcripts were only weakly upregulated in all three infected dogs, starting from 2 days up to 52 days post inoculation. The expressions of IL-2 and IL-6 genes were extremely low compared with the positive control (ConA-stimulated canine peripheral blood leukocytes). This study showed that E. canis can induce chronic expression of a subset of proinflammatory cytokine genes: balance, timing, and duration of these cytokine generations may contribute to the progression of canine ehrlichiosis.

The genome of the obligately intracellular bacterium Ehrlichia canis reveals themes of complex membrane structure and immune evasion strategies.

Ehrlichia canis, a small obligately intracellular, tick-transmitted, gram-negative, alpha-proteobacterium, is the primary etiologic agent of globally distributed canine monocytic ehrlichiosis. Complete genome sequencing revealed that the E. canis genome consists of a single circular chromosome of 1,315,030 bp predicted to encode 925 proteins, 40 stable RNA species, 17 putative pseudogenes, and a substantial proportion of noncoding sequence (27%). Interesting genome features include a large set of proteins with transmembrane helices and/or signal sequences and a unique serine-threonine bias associated with the potential for O glycosylation that was prominent in proteins associated with pathogen-host interactions. Furthermore, two paralogous protein families associated with immune evasion were identified, one of which contains poly(G-C) tracts, suggesting that they may play a role in phase variation and facilitation of persistent infections. Genes associated with pathogen-host interactions were identified, including a small group encoding proteins (n = 12) with tandem repeats and another group encoding proteins with eukaryote-like ankyrin domains (n = 7).