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Ehrlichiosis in Dogs: A Comprehensive Review about the Pathogen and Its Vectors with Emphasis on South and East Asian Countries. Vet Sci 2022; 10:vetsci10010021. [PMID: 36669021 PMCID: PMC9863373 DOI: 10.3390/vetsci10010021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 12/17/2022] [Accepted: 12/24/2022] [Indexed: 12/31/2022] Open
Abstract
Ehrlichiosis in dogs is an emerging vector borne rickettsial zoonotic disease of worldwide distribution. In general, three Ehrlichial species (Ehrlichia canis, E. ewingii, and E. chaffeensis) are involved in infecting dogs. Among them, E. canis is the well-known etiological pathogen affecting platelets, monocytes, and granulocytes. Dogs act as a reservoir, while the main vector responsible for disease transmission is Rhipicephalus sanguineus. However, in east Asian countries, Haemaphysalis longicornis is considered the principal vector for disease transmission. This disease affects multiple organs and systems and has three clinical manifestations, including acute, subclinical, and chronic. Definitive diagnosis involves visualization of morulae on cytology, detection of antibodies through an indirect immunofluorescence test (IFAT), and DNA amplification by polymerase chain reaction (PCR). In canine ehrlichiosis, no predilection of age or sex is observed; however, Siberian Huskies and German Shepherds are more likely to develop severe clinical manifestations. Doxycycline, rifampicin, and minocycline are proven to be effective drugs against canine ehrlichiosis. This review is intended to describe a brief overview of Ehrlichia infection in dogs, its reported prevalence in east and south Asian countries, and the latest knowledge regarding chemotherapy and associated vectors responsible for the disease transmission. This manuscript also identifies the prevailing knowledge gaps which merit further attention by the scientific community.
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De Lucas JJ, Rodríguez C, San Andrés MD, Sainz A, Villaescusa A, García-Sancho M, Rodríguez-Franco F, San Andrés MI. Pharmacokinetics of doxycycline after oral administration of multiple doses in dogs. J Vet Pharmacol Ther 2020; 44:326-332. [PMID: 33128251 DOI: 10.1111/jvp.12926] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 10/15/2020] [Indexed: 02/03/2023]
Abstract
The aim of this study was to determine the pharmacokinetic parameters of doxycycline in dogs and assess the efficacy of an oral drug dosage regimen of 10 mg/kg daily for 28 days through Pharmacokinetic/Pharmacodynamic (PK/PD) target analysis based on Monte Carlo simulation, using previously published data for the zoonotic pathogen Staphylococcus pseudintermedius. After a multiple-dosage regimen, the accumulation index was 1.88 ± 0.82. The Cmaxss and Cminss values were 5.18 ± 1.81 µg/ml and 1.91 ± 1.35 µg/ml, respectively. There were statistically significant differences for Cmax, Cmin at 24 hr, MRTt, AUCt and AUC∞ between days 1 and 28. The Cminss value was over the MIC of the principal pathogens, and Cmaxss was higher than the resistance values (>2 μg/ml). For AUC/MIC indices of 12, 25 and 40, the cumulative fraction responses (CFR) were 94.01%, 69.55% and 60.86%, respectively; for an MIC value of 2 µg/ml, the corresponding probability of target attainment (PTA) was 99.94%, 84.78% and 45.16%, respectively. Doxycycline was used against numerous localized infections in different organs and tissues. For the strains with MIC < 1 μg/mL, PTA was close to 100%, even for the most demanding ones, specifically 94.98% for an index of 40% and 99.9% for an index of 25.
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Affiliation(s)
- Jose Julio De Lucas
- Faculty of Veterinary Medicine, Department of Pharmacology and Toxicology, Complutense University of Madrid, Madrid, Spain
| | - Casilda Rodríguez
- Faculty of Veterinary Medicine, Department of Pharmacology and Toxicology, Complutense University of Madrid, Madrid, Spain
| | - Maria Dolores San Andrés
- Faculty of Veterinary Medicine, Department of Pharmacology and Toxicology, Complutense University of Madrid, Madrid, Spain
| | - Angel Sainz
- Faculty of Veterinary Medicine, Department of Animal Medicine and Surgery, Veterinary Clinical Hospital, Complutense University of Madrid, Madrid, Spain
| | - Alejandra Villaescusa
- Faculty of Veterinary Medicine, Department of Animal Medicine and Surgery, Veterinary Clinical Hospital, Complutense University of Madrid, Madrid, Spain
| | - Mercedes García-Sancho
- Faculty of Veterinary Medicine, Department of Animal Medicine and Surgery, Veterinary Clinical Hospital, Complutense University of Madrid, Madrid, Spain
| | - Fernando Rodríguez-Franco
- Faculty of Veterinary Medicine, Department of Animal Medicine and Surgery, Veterinary Clinical Hospital, Complutense University of Madrid, Madrid, Spain
| | - Manuel I San Andrés
- Faculty of Veterinary Medicine, Department of Pharmacology and Toxicology, Complutense University of Madrid, Madrid, Spain
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Mylonakis ME, Harrus S, Breitschwerdt EB. An update on the treatment of canine monocytic ehrlichiosis (Ehrlichia canis). Vet J 2019; 246:45-53. [PMID: 30902188 DOI: 10.1016/j.tvjl.2019.01.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 01/26/2019] [Accepted: 01/30/2019] [Indexed: 12/14/2022]
Abstract
Canine monocytic ehrlichiosis (CME), caused by Ehrlichia canis, a gram-negative, obligate intracellular bacterium, is a tick-borne disease of worldwide distribution. Experimentally, the course of E. canis infection can be sequentially divided into acute, subclinical and chronic phases, although distinction of these phases is challenging in the clinical setting. Spontaneous clinical recovery of acutely infected dogs is common; however, dogs at this stage require medical treatment in order to hasten their clinical recovery, and to prevent clinical exacerbation or death. An unpredictable proportion of subclinically infected dogs will eventually develop the chronic, severe form of ehrlichiosis, characterized by aplastic pancytopenia and high mortality. The aims of antimicrobial treatment in CME include the achievement of clinical remission, resolution of the clinicopathologic abnormalities, and eradication of the infection, although the latter is not always feasible or diagnostically confirmable. Treatment of dogs with aplastic pancytopenia should be undertaken with the clear understanding that medical management will require long-term care, will be expensive, and may eventually prove ineffective. This manuscript reviews the current state of knowledge regarding treatment of ehrlichiosis, caused by E. canis infection in dogs, provides expert opinion guidelines for the management of the CME-associated aplastic pancytopenia, and outlines methods for evaluation of treatment outcomes.
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Affiliation(s)
- Mathios E Mylonakis
- Companion Animal Clinic, School of Veterinary Medicine, Aristotle University of Thessaloniki, 11 Stavrou Voutyra st., Thessaloniki 54627, Greece.
| | - Shimon Harrus
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel
| | - Edward B Breitschwerdt
- Intracellular Pathogens Research Laboratory, Comparative Medicine Institute, College of Veterinary Medicine, North Carolina State University (NCSU-CVM),1060 William Moore Drive, Raleigh, NC 27607 USA
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Effects of Doxycycline Treatment on Hematological and Blood Biochemical Parameters in Dogs Naturally Infected with Ehrlichia canis. MACEDONIAN VETERINARY REVIEW 2018. [DOI: 10.2478/macvetrev-2018-0011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Ehrlichia canis, the etiologic agent of canine monocytic ehrlichiosis (CME), is mainly transmitted by the brown dog tick Rhipicephalus sanguineus. Clinical signs of the disease can be various, depending on the stage of the disease. Typical changes in hematological and blood biochemical parameters are: severe thrombocytopenia, mild to marked non regenerative anaemia and hypoalbuminemia. In order to present the effects of the treatment protocol on several hematological and biochemistry parameters, 34 Ehrlichia canis positive dogs were compared before and after treatment with doxycycline 10mg/kg/day, in duration of four weeks. Besides the clinical sings and laboratory findings, diagnosis was confirmed by antibody tests (Bionote, Korea, AGROLABO S.p.A., Italy). The most common clinical sings were depression, lethargy, pyrexia, vomiting and anorexia. Hematological analyses were performed on the automatic hematology analyzer Exigo EosVet (Sweden), while biochemistry analyses (alanine aminotransferase, aspartate aminotransferase, urea, creatinine, albumin, total protein, globulin and alkaline phosphatase) were performed using the automatic analyzer ChemWell 2910 (Awareness Technology, INC, USA). Statistically significant difference (p<0.05) in hematology changes was present regarding the red blood cells count, platelet count, hematocrit and hemoglobin before and after treatment. Hypoalbuminaemia (Mean 19.21 ±4.96 g/l) was the only serum biochemistry parameter with significant change before and after treatment, as well. Treatment with doxycycline in patients with E.canis resulted in significant increase of hematology parameters (red blood cells, hemoglobin, haematocrit and platelets), as well as albumins in serum.
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Mylonakis ME, Theodorou KN. Canine Monocytic Ehrlichiosis: An Update on Diagnosis and Treatment. ACTA VET-BEOGRAD 2017. [DOI: 10.1515/acve-2017-0025] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Abstract
Canine monocytic ehrlichiosis (CME) is a tick-borne disease of worldwide distribution. The major causative agent is Ehrlichia canis, a gram-negative, obligate intracellular, pleomorphic bacterium of the genus Ehrlichia, which infects monocytes, macrophages and lymphocytes, forming intracytoplasmic, membrane-bound bacterial aggregates, called morulae. After an incubation period of 8-20 days, the course of E. canis infection, can be sequentially divided into acute, subclinical and chronic phases, although these phases can hardly be distinguished in the clinical setting. Clinical recovery is the typical outcome of acutely infected dogs, entering the subclinical phase, during which they show no or minimal clinical signs and/or mild hematological abnormalities. Immunocompetent dogs may eliminate the infection during the acute or subclinical phases, but an unpredictable proportion of dogs will eventually develop the chronic phase, characterized by aplastic pancytopenia and high mortality, due to septicemia and/or severe bleeding. This article outlines briefly the pathogenesis of CME due to E. canis, and more thoroughly reviews the recent scientific literature pertaining to the diagnosis and treatment of this devastating disease.
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Affiliation(s)
- Mathios E. Mylonakis
- Konstantina N. Companion Animal Clinic, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki , Greece
| | - Konstantina N. Theodorou
- Companion Animal Clinic, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki , Greece
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Acute phase protein and antioxidant responses in dogs with experimental acute monocytic ehrlichiosis treated with rifampicin. Vet Microbiol 2016; 184:59-63. [PMID: 26854345 DOI: 10.1016/j.vetmic.2016.01.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 01/03/2016] [Accepted: 01/06/2016] [Indexed: 02/07/2023]
Abstract
There is currently lack of information on the changes of acute phase proteins (APP) and antioxidant markers and their clinical relevance as treatment response indicators in canine monocytic ehrlichiosis (CME). The objective of this study was to investigate the patterns of C-reactive protein (CRP), haptoglobin (Hp), ferritin and paraoxonase-1 (PON-1) during treatment of dogs with acute CME with rifampicin. Blood serum samples from ten Beagle dogs with experimental acute CME were retrospectively examined. Five dogs (Group A) were treated with rifampicin (10mg/Kg/24h), per os, for 3 weeks and 5 dogs (Group B) received no treatment (infected controls). Two Beagle dogs served as uninfected controls. Blood serum samples were serially examined prior to Ehrlichia canis inoculation and on post-inoculation days 14, 21, 28, 35 and 42. Significant changes of CRP, Hp, ferritin and PON-1 values were found in the majority of infected dogs. However, their concentrations did not differ between the two groups during the treatment observation period. The results of this study indicate that although several APP and PON-1 tend to significantly change in the majority of dogs with acute CME, they were of limited clinical relevance as treatment response indicators in this experimental setting.
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Fourie JJ, Horak I, Crafford D, Erasmus HL, Botha OJ. The efficacy of a generic doxycycline tablet in the treatment of canine monocytic ehrlichiosis. J S Afr Vet Assoc 2015; 86:1193. [PMID: 26018824 PMCID: PMC6138191 DOI: 10.4102/jsava.v86i1.1193] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 11/19/2014] [Accepted: 09/15/2014] [Indexed: 11/07/2022] Open
Abstract
The objective of the present study was to evaluate the therapeutic efficacy of a generic doxycycline tablet (DoxyVet®) against Ehrlichia canis infection in dogs. Canine monocytic ehrlichiosis is caused by the bacterium E. canis and transmitted by the brown kennel tick (Rhipicephalus sanguineus). Six disease-free and tick-free dogs were infested with E. canis-infected ticks. Once diagnosed (with polymerase chain reaction [PCR] analysis and platelet counts) as positive for infection, doxycycline tablets were administered orally once a day for 20 consecutive days, at a target dose level of 10 mg/kg. The actual dose administered was calculated as ranging between 10 mg/kg and 11.7 mg/kg. The PCR analysis, 28 days after the first administration of the tablets, failed to detect E. canis in any of the dogs. On Day 56 of the study, four of the dogs were diagnosed with E. canis for the second time and a fifth dog was diagnosed on Day 70. The platelet counts of the sixth dog remained within normal levels and it was discharged from the study on Day 84. Doxycycline tablets were then administered to the remaining five infected dogs for 28 consecutive days. Four of these dogs had no positive PCR results during the following 3 months. The fifth dog was diagnosed with E. canis for the third time 58 days after the last tablets of the second treatment had been administered, after which it was rescue treated (doxycycline for a further 28 days). The results indicate that doxycycline administered in tablet form (DoxyVet®) at 10 mg/kg – 11.7 mg/kg body mass once daily for 28 consecutive days clears most dogs of infection. The importance of a concomitant tick-control programme is therefore stressed.
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Affiliation(s)
| | | | - Dionne Crafford
- ClinVet International, Universitas, South Africa; Department of Zoology, University of Johannesburg, South Africa.
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Sainz Á, Roura X, Miró G, Estrada-Peña A, Kohn B, Harrus S, Solano-Gallego L. Guideline for veterinary practitioners on canine ehrlichiosis and anaplasmosis in Europe. Parasit Vectors 2015; 8:75. [PMID: 25649069 PMCID: PMC4324656 DOI: 10.1186/s13071-015-0649-0] [Citation(s) in RCA: 163] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Accepted: 01/10/2015] [Indexed: 11/30/2022] Open
Abstract
Canine ehrlichiosis and anaplasmosis are important tick-borne diseases with a worldwide distribution. Information has been continuously collected on these infections in Europe, and publications have increased in recent years. Prevalence rates are high for Ehrlichia and Anaplasma spp. infections in dogs from different European countries. The goal of this article was to provide a practical guideline for veterinary practitioners on the diagnosis, treatment, and prevention of ehrlichiosis and anaplasmosis in dogs from Europe. This guideline is intended to answer the most common questions on these diseases from a practical point of view.
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Affiliation(s)
- Ángel Sainz
- Department of Animal Medicine and Surgery, Veterinary Clinic Hospital, Faculty of Veterinary Medicine, Universidad Complutense de Madrid, Madrid, Spain.
| | - Xavier Roura
- Hospital Clinic Veterinari, Universitat Autònoma de Barcelona, Barcelona, Spain.
| | - Guadalupe Miró
- Department of Animal Health, Veterinary Clinic Hospital, Faculty of Veterinary Medicine, Universidad Complutense de Madrid, Madrid, Spain.
| | - Agustín Estrada-Peña
- Department of Animal Pathology, Faculty of Veterinary Medicine, University of Zaragoza, Zaragoza, Spain.
| | - Barbara Kohn
- Small Animal Clinic, Faculty of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
| | - Shimon Harrus
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel.
| | - Laia Solano-Gallego
- Departament de Medicina i Cirurgia Animal, Facultat de Veterinaria, Universitat Autònoma de Barcelona, Bellaterra, Spain.
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Allison RW, Little SE. Diagnosis of rickettsial diseases in dogs and cats. Vet Clin Pathol 2013; 42:127-44. [DOI: 10.1111/vcp.12040] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robin W. Allison
- Department of Veterinary Pathobiology; Center for Veterinary Health Sciences; Oklahoma State University; Stillwater; OK; USA
| | - Susan E. Little
- Department of Veterinary Pathobiology; Center for Veterinary Health Sciences; Oklahoma State University; Stillwater; OK; USA
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Theodorou K, Mylonakis ME, Siarkou VI, Leontides L, Koutinas AF, Koutinas CK, Kritsepi-Konstantinou M, Batzias G, Flouraki E, Eyal O, Kontos V, Harrus S. Efficacy of rifampicin in the treatment of experimental acute canine monocytic ehrlichiosis. J Antimicrob Chemother 2013; 68:1619-26. [PMID: 23475646 DOI: 10.1093/jac/dkt053] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES To assess the efficacy of rifampicin in achieving clinical and haematological recovery and clearing infection in dogs with experimentally induced acute monocytic ehrlichiosis. METHODS Five Ehrlichia canis-infected Beagle dogs were treated with rifampicin (10 mg/kg/24 h orally for 3 weeks), nine E. canis-infected dogs received no treatment (infected untreated dogs) and two dogs served as uninfected controls. Clinical score, platelet counts, immunofluorescent antibody titres and PCR detection of E. canis-specific DNA in blood, bone marrow and spleen aspirates were evaluated on post-inoculation days 21 (start of rifampicin), 42 (end of rifampicin) and 98 (end of the study). RESULTS By day 21 post-inoculation, all infected dogs became clinically ill and thrombocytopenic, seroconverted and were PCR positive in at least one tissue. Clinical scores and antibody titres did not differ between the treated and infected untreated dogs throughout the study. The rifampicin-treated dogs experienced an earlier resolution of their thrombocytopenia (Kaplan-Meier survival plot, P=0.048), and the median platelet counts were significantly higher in the treated compared with the infected untreated dogs on post-inoculation days 42 (P=0.0233) and 98 (P=0.0195). At the end of the study, three treated and six untreated infected dogs remained PCR positive in one tissue each. CONCLUSIONS The rifampicin treatment regimen applied in this study hastened haematological recovery, but was inconsistent in eliminating the acute E. canis infection.
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Affiliation(s)
- Konstantina Theodorou
- Companion Animal Clinic, Faculty of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Kelly PJ, Xu C, Lucas H, Loftis A, Abete J, Zeoli F, Stevens A, Jaegersen K, Ackerson K, Gessner A, Kaltenboeck B, Wang C. Ehrlichiosis, babesiosis, anaplasmosis and hepatozoonosis in dogs from St. Kitts, West Indies. PLoS One 2013; 8:e53450. [PMID: 23335965 PMCID: PMC3546050 DOI: 10.1371/journal.pone.0053450] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 11/28/2012] [Indexed: 12/03/2022] Open
Abstract
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.
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Affiliation(s)
- Patrick J. Kelly
- Ross University School of Veterinary Medicine, St. Kitts, West Indies
| | - Chuanling Xu
- Yangzhou University, Yangzhou, Jiangsu, People’s Republic of China
| | - Helene Lucas
- Ross University School of Veterinary Medicine, St. Kitts, West Indies
| | - Amanda Loftis
- Ross University School of Veterinary Medicine, St. Kitts, West Indies
| | - Jamie Abete
- Ross University School of Veterinary Medicine, St. Kitts, West Indies
| | - Frank Zeoli
- Ross University School of Veterinary Medicine, St. Kitts, West Indies
| | - Audrey Stevens
- Ross University School of Veterinary Medicine, St. Kitts, West Indies
| | - Kirsten Jaegersen
- Ross University School of Veterinary Medicine, St. Kitts, West Indies
| | - Kate Ackerson
- Ross University School of Veterinary Medicine, St. Kitts, West Indies
| | - April Gessner
- Ross University School of Veterinary Medicine, St. Kitts, West Indies
| | - Bernhard Kaltenboeck
- College of Veterinary Medicine, Auburn University, Auburn, Alabama, United States of America
| | - Chengming Wang
- Yangzhou University, Yangzhou, Jiangsu, People’s Republic of China
- * E-mail:
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Rudoler N, Baneth G, Eyal O, van Straten M, Harrus S. Evaluation of an attenuated strain of Ehrlichia canis as a vaccine for canine monocytic ehrlichiosis. Vaccine 2012; 31:226-33. [PMID: 23072894 DOI: 10.1016/j.vaccine.2012.10.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 07/20/2012] [Accepted: 10/03/2012] [Indexed: 10/27/2022]
Abstract
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.
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Affiliation(s)
- Nir Rudoler
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot 76100, Israel
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Abstract
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.
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Affiliation(s)
- Susan E Little
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078-2007, USA.
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Efficacy of a doxycycline treatment regimen initiated during three different phases of experimental ehrlichiosis. Antimicrob Agents Chemother 2010; 54:5012-20. [PMID: 20921310 DOI: 10.1128/aac.01622-09] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Doxycycline is the treatment of choice for canine monocytic ehrlichiosis (CME), a well-characterized disease and valuable model for tick-borne zoonoses. Conflicting reports of clearance of Ehrlichia canis after treatment with doxycycline suggested that the disease phase during which treatment is initiated influences outcomes of these treatments. The purpose of this study was to evaluate the efficacy of a 28-day doxycycline regimen for clearance of experimental E. canis infections from dogs treated during three phases of the disease. Ten dogs were inoculated with blood from E. canis carriers and treated with doxycycline during acute, subclinical, or chronic phases of CME. Daily rectal temperatures and semiweekly blood samples were monitored from each dog, and Rhipicephalus sanguineus ticks were acquisition fed on each dog for xenodiagnosis. Blood collected from dogs treated during acute or subclinical CME became PCR negative for E. canis as clinical parameters improved, but blood samples collected from dogs treated during chronic CME remained intermittently PCR positive. R. sanguineus ticks fed on dogs after doxycycline treatments became PCR positive for E. canis, regardless of when treatment was initiated. However, fewer ticks became PCR positive after feeding on two persistently infected dogs treated with doxycycline followed by rifampin, suggesting that antibiotic therapy can reduce tick acquisition of E. canis.
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Experimental infection and co-infection of dogs with Anaplasma platys and Ehrlichia canis: hematologic, serologic and molecular findings. Parasit Vectors 2010; 3:33. [PMID: 20377870 PMCID: PMC2859368 DOI: 10.1186/1756-3305-3-33] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 04/08/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Rhipicephalus sanguineus is a ubiquitous tick responsible for transmitting Ehrlichia canis and most likely Anaplasma platys to dogs, as either single or co-infections. The objective of this study was to assess the effects of either simultaneous or sequential experimental infections with E. canis and A. platys on hematological and serological parameters, duration of infection, and efficacy of doxycycline therapy in dogs infected with one or both organisms. Six dogs per group were either uninfected, A. platys infected, E. canis infected, A. platys and E. canis co-infected, A. platys infected and E. canis challenged or E. canis infected and A. platys challenged at day 112 post-infection (PI). Doxycycline treatment was initiated at 211 days PI, followed by dexamethasone immunosuppression beginning 410 days PI. RESULTS Initially, transient decreases in hematocrit occurred in all groups infected with E. canis, but the mean hematocrit was significantly lower in the A. platys and E. canis co-infected group. All dogs except the controls developed marked thrombocytopenia after initial infection followed by gradually increased platelet counts by 112 days PI in groups with the single infections, while platelet counts remained significantly lower in the A. platys and E. canis co-infected group. Both sequential and simultaneous infections of A. platys and E. canis produced an enhanced humoral immune response to A. platys when compared to infection with A. platys alone. Likewise, co-infection with E. canis and A. platys resulted in a more persistent A. platys infection compared to dogs infected with A. platys only, but nearly all A. platys infected dogs became A. platys PCR negative prior to doxycycline treatment. E. canis infected dogs, whether single or co-infected, remained thrombocytopenic and E. canis PCR positive in blood for 420 days. When treated with doxycycline, all E. canis infected dogs became E. canis PCR negative and the thrombocytopenia resolved. Despite immunosuppression, neither A. platys nor E. canis DNA was PCR amplified from doxycycline-treated dogs. CONCLUSIONS The results of this study demonstrate that simultaneous or sequential infection with A. platys and E. canis can alter various pathophysiological parameters in experimentally infected dogs, and because natural exposure to multiple tick-borne pathogens occurs frequently in dogs, awareness of co-infection is important in clinical practice.
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