Ehrlichia platys (Anaplasma platys) in dogs from Maracaibo,Venezuela: an ultrastructural study of experimental and natural infections

Since 1982 Ehrlichia platys, now emended as Anaplasma platys, has been diagnosed in dogs from Maracaibo, Venezuela, using buffy coat smears stained with Dip Quick. Three dogs were inoculated with an A. platys strain. When parasitemia reached 60-97%, blood samples obtained from the inoculated dogs and from two naturally infected dogs were centrifuged to obtain platelet-rich plasma, which was mixed with 0.1% glutaraldehyde at 37 C for 10 minutes. Platelet pellets were fixed in 3% glutaraldehyde for 72 hours and processed for conventional transmission electron microscopy. Platelets contained pleomorphic organisms with a distinct double membrane that was not observed when the bodies were in a determinate developmental stage. There were 1-15 individual bodies included in a host cell vacuole. The organisms had an electron-lucent inner area, whereas the internal surface of their inner plasma membranes exhibited an electron-dense rough substance. In naturally infected dogs, organisms with different ultrastructural features were found inside the same platelet. Some organisms contained central dense material surrounded by a pale zone, which was in turn surrounded by a moderately dense peripheral area. Other organisms contained an eccentrically electron-dense material. The intravacuolar space appeared fully electron-lucent. Each organism usually exhibited inner fine strands. Empty structures displaying junctions with the vacuolar membrane were observed. Our results indicate that distinct ultrastructural characteristics are associated with different stages of A. platys development and may differ among A. platys strains.     

Prevalence,molecular characterization and risk factor analysis of Ehrlichia canis and Anaplasma platys in domestic dogs from Paraguay

This is the first study to investigate the prevalence and risk factors associated with Ehrlichia canis and Anaplasma platys positivity in dogs from Paraguay. Conventional PCR assays for the E. canis 16SrRNA gene and A. platys p44 gene were carried out in blood samples from 384 dogs from Asunción city, Paraguay. Sequencing and phylogenetic analysis were performed in selected positive E. canis and (16SrRNA gene) and A. platys (16S and p44 genes) samples. The overall prevalence of E. canis and A. platys in dogs in Paraguay was 10.41% (40/384) and 10.67% (41/384), respectively. Older dogs without veterinary care had higher odds for E. canis positivity and a higher number of dogs in the same household, as well as absence of anti-tick treatment were considered risk factors for A. platys. Ehrlichia canis and A. platys circulate in the dog population from Asunción, and are described for the first time in Paraguay.     

Molecular detection of Anaplasma platys and Ehrlichia canis in dogs from the North of Portugal

Tick-transmitted rickettsial pathogens belonging to the Ehrlichia and Anaplasma genera can infect dogs and humans. In this study, four dogs from the North of Portugal, in which an ehrlichial disease was suspected clinically, were tested by molecular methods. After DNA extraction from blood on filter paper, a 345 bp fragment of the Ehrlichia/Anaplasma 16S rRNA gene was amplified by the polymerase chain reaction (PCR). Sequence analysis of PCR products revealed one dog infected with Ehrlichia canis and three with Anaplasma platys. One of these latter animals was co-infected with Babesia canis subspecies vogeli. This is the first report of the genetic characterisation of both A. platys and E. canis in naturally infected dogs from the North of Portugal.     

Epidemiological survey of Anaplasma platys and Ehrlichia canis using ticks collected from dogs in Japan

Detection of Anaplasma platys and Ehrlichia canis in ticks recovered from dogs in Japan was attempted using a species-specific nested PCR based on the 16S rRNA gene. A total of 1211 ticks recovered from 1211 dogs from all over Japan were examined for A. platys and E. canis. Four tick samples from Fukushima, Miyazaki and Kagoshima Prefectures recovered from four different dogs showed a positive reaction for A. platys. Although the four dogs did not show any clinical signs and no blood examination data were available, it is possible that A. platys has already been spread widely in Japan. No positive reactions were observed in any ticks examined for E. canis.     

Detection of Ehrlichia platys in dogs in Australia

OBJECTIVE: To describe the detection of Ehrlichia platys in free-roaming dogs in Central Australia. PROCEDURE: Blood samples were collected from four dogs and examined for bacterial 16S ribosomal DNA using Polymerase Chain Reaction (PCR)-based assays. The three positive samples obtained were then sequenced and identification of the PCR product carried out. As a result of all three samples being identical to or closely related to part of the 16S rRNA gene of E. platys, blood samples were subsequently obtained from a further 24 dogs. These samples were screened using a PCR-assay to determine the presence of Ehrlichia DNA using genus-specific primers. The positive samples obtained from the screening process were then subjected to a further PCR-assay using E. platys specific primers. RESULTS: Of 28 dogs sampled, Ehrlichia DNA was detected in the blood of 13 dogs. Sequencing of the amplicons obtained indicated a high homology with the 16S rRNA gene for E. platys. When the E. platys-specific PCR was performed for 10 of those dogs, the 678 bp product obtained from the PCR amplification confirmed the identification as part of the 16S rRNA gene of E. platys in all 10 dogs. CONCLUSION: This study reports for the first time Ehrlichia carriage by dogs in Australia. It also indicates the usefulness of the PCR technique in rapidly and accurately identifying diseases that are otherwise difficult to detect. By using universal primers directed against bacterial 16S ribosomal DNA and sequencing analysis, the detection of potentially pathogenic Ehrlichia organisms that had not previously been found in Australia has been made possible.     

Demonstration of Anaplasma (Ehrlichia) platys inclusions in peripheral blood platelets of a dog in Japan

A free-roaming dog in Okinawa island showed Anaplasma (Ehrlichia) platys-like inclusions within the platelets of peripheral blood samples. The inclusions were positive in indirect fluorescence test with anti-A. phagocytophila serum. The platelet count of the dog was 170,000 microl(-1). The sequence analysis of the 16S rRNA, citrate synthase and heat shock protein genes of DNA from the infected platelets confirmed that the inclusions were A. platys. This is the first detection of A. platys inclusions in dogs in Japan.     

Anemia of inflammation in dogs infected with Ehrlichia platys

Ten adult male dogs were inoculated with Ehrlichia platys, and blood samples were collected throughout the infection to evaluate the hematologic changes with respect to serum biochemical analytes. All dogs developed a mild, normocytic, normochromic anemia by postinoculation day 7, with significantly (P less than 0.05) decreased serum iron concentration and total iron-binding capacity. Stainable bone marrow iron appeared normal or increased throughout the infection. By postinoculation day 31, the PCV was not significantly different from the pretreatment value. All dogs became hypergammaglobulinemic, leukopenic, hypoalbuminemic, and hypocalcemic during the infection. These findings were compatible with the syndrome of anemia of inflammation.     

Platelet aggregation studies in dogs with acute Ehrlichia platys infection

Ten adult dogs (5 Beagles and 5 mixed-breed dogs) were inoculated IV with canine platelets containing Ehrlichia platys. Inclusions and morulae of E platys developed in platelets of infected dogs at 10 to 14 days after inoculation, followed by marked thrombocytopenia at 14 to 21 days. Parasitemia and marked thrombocytopenia recurred at 24 to 28 days after inoculation. Increased numbers of megakaryocytes were observed in marrow aspirate smears from infected dogs, indicative of regenerative thrombocytopenia. Prior to infection, platelet-rich plasma from these dogs was determined to have similar aggregatory response to arachidonate. After infection with E platys, the aggregatory response of platelet-rich plasma to collagen or 3 dilutions of adenosine diphosphate was evaluated. A statistically significant (P less than 0.05) inhibition of platelet aggregatory response to the lowest dilution of adenosine diphosphate was detected for mixed-breed dogs, whereas aggregation responses were unchanged in Beagles. Results indicate that platelet activation may occur in dogs with acute ehrlichial infection.     

Babesia canis vogeli,Ehrlichia canis,and Anaplasma platys infection in a dog

A 12‐month‐old male neutered mixed breed dog was presented with a history of diarrhea, lethargy, emaciation, polydypsia, and sniffling. Physical examination findings included pale mucous membranes, increased heart and respiratory rates, and normal rectal temperature (38°C). Hematologic abnormalities included anemia and thrombocytopenia. Biochemical abnormalities included hypoalbuminemia, hyperbilirubinemia, and elevated ALP and ALT activities. A SNAP 4Dx test result was positive for Ehrlichia canis. Babesia canis vogeli organisms were found in the peripheral blood films, while morulae of E canis were not seen. Real‐time polymerase chain reaction testing confirmed the presence of both B c vogeli and E canis organisms, and also was positive for Anaplasma platys infection. The dog recovered following treatment with doxycycline and imidocarb dipropionate, with normal hematology and biochemical profiles.     

Detection of Anaplasma platys in dogs using real-time loop-mediated isothermal amplification

Anaplasma platys is a parasite of canine platelets that causes infectious cyclic thrombocytopenia. In this study, a novel real-time loop-mediated isothermal amplification (RT-LAMP) method was developed to detect A. platys. RT-LAMP primer sets were designed using a citrate synthase gene sequence and the assay was performed at 63 °C for 30 min. No cross-reactivity was observed with other Anaplasma or Ehrlichia spp. and the method exhibited a similar level of sensitivity in detecting the organism in 58 canine blood samples to that of a nested PCR. This RT-LAMP is a rapid and potentially cost-effective method of diagnosing A. platys infection in dogs.     

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.     

First evidence of Anaplasma platys in Rhipicephalus sanguineus (Acari: Ixodida) collected from dogs in Africa

A total of 27 ticks, comprising Rhipicephalus sanguineus (Latreille) (n = 21), Haemaphysalis leachi (Andouin) (n = 4) and Haemaphysalis paraleachi (Camicas, Hoogstraal & El Kammah) (n = 2) were recovered from two clinically healthy female dogs in the Democratic Republic of the Congo. DNA of Anaplasma platys was detected in a female R. sanguineus, using primers derived from the 16S rRNA gene, which amplify members of the family Anaplasmataceae . Anaplasma platys DNA was also detected in the blood of one of the dogs. Phylogenetic analysis based on partial sequences of the 16S rRNA, the gltA and the groEL genes ranged the detected agent within the Anaplasma clade. This is the first reported detection of A. platys in ticks in Africa. This finding raises the question of the possible involvement of R. sanguineus in A. platys infection of dogs.     

Acute Ehrlichia platys infection in the dog

Ten dogs were inoculated with Ehrlichia platys (E. platys) from an acutely infected dog. Two dogs were necropsied on each of days 7, 14, 21, 28, and 35 post-inoculation, and tissues were collected and either fixed in formalin or frozen for light microscopic examination of lesions or E. platys antigen localization in tissues. Serum antibody titers to E. platys and serum aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase activities were also determined. The significant light microscopic findings were lymph node follicular hyperplasia and crescent-shaped hemorrhages in the splenic periarteriolar lymphoid sheaths beginning day 7 post-inoculation. There was significant megakaryocyte hyperplasia of bone marrow on days 28 and 35 post-inoculation. Ehrlichia platys antigen was in macrophages at 14 days post-inoculation which corresponded to the initial decline in platelet numbers. Initial thrombocytopenia and splenic crescent-shaped hemorrhages were temporally related, however the degree of lesion development and prominence were not related to subsequent platelet numbers.     

Prevalence of Ehrlichia canis, Anaplasma platys, Babesia canis vogeli, Hepatozoon canis, Bartonella vinsonii berkhoffii, and Rickettsia spp. in dogs from Grenada

To identify the tick-borne pathogens in dogs from Grenada, we conducted a serologic survey for Ehrlichia canis in 2004 (104 dogs) and a comprehensive serologic and molecular survey for a variety of tick-borne pathogens in 2006 (73 dogs). In 2004 and 2006, 44 and 32 dogs (42.3% and 43.8%) were seropositive for E. canis, respectively. In 2006, several tick-borne pathogens were identified by serology and PCR. DNA of E. canis, Anaplasma platys, Babesia canis vogeli, Hepatozoon canis, and Bartonella sp. were identified in 18 (24.7%), 14 (19.2%), 5 (7%), 5 (7%), and 1 (1.4%) dogs, respectively. Six (8.2%) dogs were seropositive for Bartonella vinsonii subsp. berkhoffii. All dogs were seronegative and PCR-negative for Rickettsia spp. Coinfection with two or three pathogens was observed in eight dogs. Partial 16S rRNA E. canis and A. platys sequences were identical to sequences in GenBank. Partial 18S rRNA gene sequences from the Grenadian H. canis were identical to each other and had one possible mismatch (ambiguous base) from H. canis detected from Spain and Brazil. Grenadian B. c. vogeli sequences were identical to B. c. vogeli from Brazil and Japan. All of the detected pathogens are transmitted, or suspected to be transmitted, by Rhipicephalus sanguineus. Results of this study indicate that dogs from Grenada are infected with multiple tick-borne pathogens; therefore, tick-borne diseases should be included as differentials for dogs exhibiting thrombocytopenia, leukopenia, fever, or lethargy. One pathogen, E. canis, is also of potential public health significance.     

Immunocytochemical detection of Ehrlichia platys antigens in canine blood platelets

An avidin-biotin immunoperoxidase complex (ABC) immunocytochemical (ICC) stain procedure was optimized for detection of Ehrlichia platys antigens. Positive immunoreactivity was detected with dilutions of canine immune serum on acetone-fixed smears of platelet-rich plasma from E. platys-infected dogs. No E. platys antigens were detected when this ICC stain was applied to frozen or paraffin-embedded formalin- or acetone-fixed tissue sections from dogs with acute E. platys infection. Acetone fixation and freezing preserved ICC staining of ehrlichial antigens in infected blood platelets, whereas formalin treatment of similarly preserved E. platys-infected platelets nullified positive immunoreactivity. Significant E. platys infection of cells and tissues other than platelets may not occur.     

Molecular detection of Anaplasma platys in dogs using polymerase chain reaction and reverse line blot hybridization.

Several polymerase chain reactions (PCRs) and a reverse line blot hybridization (RLB) method were used to identify Anaplasma platys in dogs held in a kennel in Italy. Whereas PCR techniques confirmed the presence of A. platys, the RLB method not only correlated the results obtained by PCR but also ruled out the presence of other species such as Ehrlichia canis or E. chaffeensis. There was no correlation between infection status and age or breed of the dogs. Polymerase chain reaction performed on the Rhipicephalus sanguineus ticks collected from those dogs showed that they were also infected with A. platys. Sequences obtained from some samples and compared with those within the GenBank also confirmed the presence of A. platys.     

First isolation and molecular characterization of Ehrlichia canis in Spain

This paper reports the first isolation and culture of Ehrlichia canis in Spain from a naturally infected dog using the DH82 cell line. After DNA extraction and PCR amplification, a nearly complete (1412bp) sequence of the 16S rRNA gene of the new E. canis strain was obtained. The GenBank accession number for the nucleotide sequence of this strain is AY394465. This sequence was aligned with the 16S rRNA gene sequences of other Ehrlichia strains accessible in GenBank. The 16S rRNA gene sequence of the E. canis strain reported here showed a high percentage of similarity with the 16S rRNA gene sequence of E. canis from different geographic areas including Japan, Venezuela and Israel. These data confirm the presence of E. canis in Spain.