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Sullivan MD, Glose K, Sward D. Tick-Borne Illnesses in Emergency and Wilderness Medicine. Emerg Med Clin North Am 2024; 42:597-611. [PMID: 38925777 DOI: 10.1016/j.emc.2024.02.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2024]
Abstract
This review highlights the causative organisms, clinical features, diagnosis, and treatment of the most common tick-borne illnesses in the United States, including Lyme disease, Rocky Mountain spotted fever, anaplasmosis, ehrlichiosis, tularemia, Powassan virus, and alpha-gal syndrome. Tick bite prevention strategies and some basic tick removal recommendations are also provided.
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Affiliation(s)
- Michael D Sullivan
- Department of Emergency Medicine, University of Maryland Medical Center, 6th Floor, Suite 200, 110 South Paca Street, Baltimore, MD 21201, USA
| | - Kyle Glose
- Department of Emergency Medicine, University of Maryland Medical Center, 6th Floor, Suite 200, 110 South Paca Street, Baltimore, MD 21201, USA
| | - Douglas Sward
- Department of Emergency Medicine, University of Maryland School of Medicine, 6th Floor, Suite 200, 110 South Paca Street, Baltimore, MD 21201, USA.
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Gygax L, Schudel S, Kositz C, Kuenzli E, Neumayr A. Human monocytotropic ehrlichiosis-A systematic review and analysis of the literature. PLoS Negl Trop Dis 2024; 18:e0012377. [PMID: 39093857 PMCID: PMC11324158 DOI: 10.1371/journal.pntd.0012377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 08/14/2024] [Accepted: 07/17/2024] [Indexed: 08/04/2024] Open
Abstract
Human monocytotropic ehrlichiosis (HME) is a tick-borne bacterial infection caused by Ehrlichia chaffeensis. Most available data come from case reports, case series and retrospective studies, while prospective studies and clinical trials are largely lacking. To obtain a clearer picture of the currently known epidemiologic distribution, clinical and paraclinical presentation, diagnostic aspects, complications, therapeutic aspects, and outcomes of HME, we systematically reviewed the literature and analyzed and summarized the data. Cases of HME are almost exclusively reported from North America. Human infections due to other (non-chaffeensis) Ehrlichia spp. are rare. HME primarily presents as an unspecific febrile illness (95% of the cases), often accompanied by thrombocytopenia (79.1% of the cases), leukopenia (57.8% of the cases), and abnormal liver function tests (68.1% of the cases). Immunocompromized patients are overrepresented among reviewed HME cases (26.7%), which indicates the role of HME as an opportunistic infection. The incidence of complications is higher in immunocompromized compared to immunocompetent cases, with ARDS (34% vs 19.8%), acute renal failure (34% vs 15.8%), multi organ failure (26% vs 14.9%), and secondary hemophagocytic lymphohistiocytosis (26% vs 14.9%) being the most frequent reported. The overall case fatality is 11.6%, with a significant difference between immunocompetent (9.9%) and immunocompromized (16.3%) cases, and sequelae are rare (4.2% in immunocompetent cases, 2.5% in immunocompromised cases).
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Affiliation(s)
- Larissa Gygax
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Sophie Schudel
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Christian Kositz
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Esther Kuenzli
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Andreas Neumayr
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- Department of Public Health and Tropical Medicine, College of Public Health, Medical and Veterinary Sciences, James Cook University, Queensland, Australia
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Sanchez-Vicente S, Tokarz R. Tick-Borne Co-Infections: Challenges in Molecular and Serologic Diagnoses. Pathogens 2023; 12:1371. [PMID: 38003835 PMCID: PMC10674443 DOI: 10.3390/pathogens12111371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/14/2023] [Accepted: 11/18/2023] [Indexed: 11/26/2023] Open
Abstract
Co-infections are a poorly understood aspect of tick-borne diseases. In the United States alone, nineteen different tick-borne pathogens have been identified. The majority of these agents are transmitted by only two tick species, Ixodes scapularis and Amblyomma americanum. Surveillance studies have demonstrated the presence of multiple pathogens in individual ticks suggesting a risk of polymicrobial transmission to humans. However, relatively few studies have explored this relationship and its impact on human disease. One of the key factors for this deficiency are the intrinsic limitations associated with molecular and serologic assays employed for the diagnosis of tick-borne diseases. Limitations in the sensitivity, specificity and most importantly, the capacity for inclusion of multiple agents within a single assay represent the primary challenges for the accurate detection of polymicrobial tick-borne infections. This review will focus on outlining these limitations and discuss potential solutions for the enhanced diagnosis of tick-borne co-infections.
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Affiliation(s)
- Santiago Sanchez-Vicente
- Center for Infection and Immunity, Mailman School of Public Health, Columbia University, New York, NY 10032, USA;
| | - Rafal Tokarz
- Center for Infection and Immunity, Mailman School of Public Health, Columbia University, New York, NY 10032, USA;
- Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
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Efficacy and Immune Correlates of OMP-1B and VirB2-4 Vaccines for Protection of Dogs from Tick Transmission of Ehrlichia chaffeensis. mBio 2022; 13:e0214022. [PMID: 36342170 PMCID: PMC9765013 DOI: 10.1128/mbio.02140-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Ehrlichia chaffeensis, an obligatory intracellular bacterium, causes human monocytic ehrlichiosis, an emerging disease transmitted by the Lone Star tick, Amblyomma americanum. Here, we investigated the vaccine potential of OMP-1B and VirB2-4. Among the highly expressed and immunodominant E. chaffeensis porin P28s/OMP-1s, OMP-1B is predominantly expressed by E. chaffeensis in A. americanum ticks, whereas VirB2-4 is a pilus protein of the type IV secretion system essential for E. chaffeensis infection of host cells. Immunization with recombinant OMP-1B (rOMP-1B) or recombinant VirB2-4 (rVirB2-4) protected mice from E. chaffeensis infection as effectively as Entry-triggering protein of Ehrlichia immunization. Dogs vaccinated with a nanoparticle vaccine composed of rOMP-1B or rVirB2-4 and an immunostimulating complex developed high antibody titers against the respective antigen. Upon challenge with E. chaffeensis-infected A. americanum ticks, E. chaffeensis was undetectable in the blood of rOMP-1B or rVirB2-4 immunized dogs on day 3 or 6 post-tick attachment and for the duration of the experiment, whereas dogs sham-vaccinated with the complex alone were persistently infected for the duration of the experiment. E. chaffeensis exponentially replicates in blood-feeding ticks to facilitate transmission. Previously infected ticks removed from OMP-1B-immunized dogs showed significantly lower bacterial load relative to ticks removed from sham-immunized dogs, suggesting in-tick neutralization. Peripheral blood leukocytes from rVirB2-4-vaccinated dogs secreted significantly elevated amounts of interferon-γ soon after tick attachment by ELISpot assay and reverse transcription-quantitative PCR, suggesting interferon-γ-mediated Ehrlichia inhibition. Thus, Ehrlichia surface-exposed proteins OMP-1B and VirB2-4 represent new potential vaccine candidates for blocking tick-borne ehrlichial transmission. IMPORTANCE Ehrlichia are tick-borne pathogens that cause a potentially fatal illness-ehrlichiosis-in animals and humans worldwide. Currently, no vaccine is available for ehrlichiosis, and treatment options are limited. Ticks are biological vectors of Ehrlichia, i.e., Ehrlichia exponentially replicates in blood-sucking ticks before infecting animals. Ticks also inoculate immunomodulatory substances into animals. Thus, it is important to study effects of candidate vaccines on Ehrlichia infection in both animals and ticks and the immune responses of animals shortly after infected tick challenge. Here, we investigated the efficacy of vaccination with functionality-defined two surface-exposed outer membrane proteins of Ehrlichia chaffeensis, OMP-1B and VirB2-4, in a mouse infection model and then in a dog-tick transmission model. Our results begin to fill gaps in our understanding of Ehrlichia-derived protective antigens against tick-transmission and immune correlates and mechanisms that could help future development of vaccines for immunization of humans and animals to counter tick-transmitted ehrlichiosis.
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Brown Marusiak A, Hollingsworth BD, Abernathy H, Alejo A, Arahirwa V, Mansour O, Giandomenico D, Schmitz J, Williams C, Barbarin AM, Boyce RM. Patterns Testing for Tick-Borne Diseases and Implications for Surveillance in the Southeastern US. JAMA Netw Open 2022; 5:e2212334. [PMID: 35576005 PMCID: PMC9112065 DOI: 10.1001/jamanetworkopen.2022.12334] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
IMPORTANCE Tick-borne diseases (TBD), including spotted fever group rickettsiosis (SFGR), ehrlichiosis, and, increasingly, Lyme disease, represent a substantial public health concern throughout much of the southeastern United States. Yet, there is uncertainty about the epidemiology of these diseases because of pitfalls in existing diagnostic test methods. OBJECTIVE To examine patterns of diagnostic testing and incidence of TBD in a large, academic health care system. DESIGN, SETTING, AND PARTICIPANTS This cross-sectional study included diagnostic test results for TBD at UNC Health, a large academic health care system with inpatient and outpatient facilities, from January 1, 2017, to November 30, 2020. Participants included all individuals seeking routine care at UNC Health facilities who had testing for SFGR, ehrlichiosis, or Lyme disease performed during the study period. MAIN OUTCOMES AND MEASURES Rates of test positivity, testing completeness, and incidence of TBD. RESULTS During the 4-year study period, 11 367 individuals (6633 [58.4%] female; 10 793 [95%] non-Hispanic individuals and 8850 [77.9%] White individuals; median [IQR] age, 53 [37-66] years) were tested for TBD. Among the 20 528 diagnostic tests performed, 47 laboratory-confirmed, incident cases of SFGR, 27 cases of ehrlichiosis, and 76 cases of Lyme were confirmed, representing incidence rates of 4.7%, 7.1%, and 0.7%, respectively. However, 3984 of SFGR tests (79.3%) and 3606 of Ehrlichia tests (74.3%) lacked a paired convalescent sample. Of 20 528 tests, there were 11 977 tests (58.3%) for Lyme disease from 10 208 individuals, 5448 tests (26.5%) for SFGR from 4520 individuals, and 3103 tests (15.1%) for ehrlichiosis from 2507 individuals. Most striking, testing for ehrlichiosis was performed in only 55% of patients in whom SFGR was ordered, suggesting that ehrlichiosis remains underrecognized. An estimated 187 incident cases of SFGR and 309 of ehrlichiosis were potentially unidentified because of incomplete testing. CONCLUSIONS AND RELEVANCE In this cross-sectional study, most of the patients suspected of having TBD did not have testing performed in accordance with established guidelines, which substantially limits understanding of TBD epidemiology. Furthermore, the data revealed a large discrepancy between the local burden of disease and the testing performed. These findings underscore the need to pursue more robust, active surveillance strategies to estimate the burden of TBD and distribution of causative pathogens.
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Affiliation(s)
- Amanda Brown Marusiak
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Brandon D. Hollingsworth
- Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Haley Abernathy
- Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Aidin Alejo
- Department of Pathology and Laboratory Medicine, McLendon Clinical Laboratories, UNC Health, Chapel Hill, North Carolina
| | - Victor Arahirwa
- Department of Pathology and Laboratory Medicine, McLendon Clinical Laboratories, UNC Health, Chapel Hill, North Carolina
| | - Odai Mansour
- Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Dana Giandomenico
- Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - John Schmitz
- Department of Pathology and Laboratory Medicine, McLendon Clinical Laboratories, UNC Health, Chapel Hill, North Carolina
| | - Carl Williams
- Division of Public Health, Communicable Disease Branch, Raleigh, North Carolina
| | - Alexis M. Barbarin
- Division of Public Health, Communicable Disease Branch, Raleigh, North Carolina
| | - Ross M. Boyce
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Dixon DM, Branda JA, Clark SH, Dumler JS, Horowitz HW, Perdue SS, Pritt BS, Sexton DJ, Storch GA, Walker DH. Ehrlichiosis and anaplasmosis subcommittee report to the Tick-borne Disease Working Group. Ticks Tick Borne Dis 2021; 12:101823. [PMID: 34517150 DOI: 10.1016/j.ttbdis.2021.101823] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 08/18/2021] [Accepted: 08/29/2021] [Indexed: 10/20/2022]
Abstract
Ehrlichioses and anaplasmosis have undergone dramatic increases in incidence, and the geographic ranges of their occurrence and vectors have also expanded. There is marked underreporting of these diseases owing to deficient physician awareness and knowledge of the illnesses as well as limited access to appropriate diagnostic tests. Human monocytic ehrlichiosis and anaplasmosis are life threatening diseases with estimated case fatality rates of 2.7 and 0.3%, respectively. However, knowledge of their full range of signs and symptoms is incomplete, and the incidence of subclinical infections is unknown. Currently available laboratory diagnostic methods are poorly utilized, and with the exception of nucleic acid amplification tests are not useful for diagnosis during the acute stage of illness when timely treatment is needed. The Ehrlichiosis and Anaplasmosis Subcommittee of the Tick-Borne Disease Working Group recommended active clinical surveillance to determine the true incidence, full clinical spectrum, and risk factors for severe illness, as well as standardized surveillance of ticks for these pathogens, and enhanced education of primary medical caregivers and the public regarding these diseases. The subcommittee identified the needs to develop sensitive, specific acute stage diagnostic tests for local clinical laboratories and point-of-care testing, to develop approaches for utilizing electronic medical records, data mining, and artificial intelligence for assisting early diagnosis and treatment, and to develop adjunctive therapies for severe disease.
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Affiliation(s)
| | - John A Branda
- Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114, United States.
| | - Stephen H Clark
- University of Connecticut School of Medicine, 200 Academic Way, Farmington, CT 06032, United States
| | - J Stephen Dumler
- Uniformed Services University of the Health Sciences, Walter Reed National Military Medical Center, Joint Pathology Center, 4301 Jones Bridge Road, Building B, Room 3152, Bethesda, MD 20814, United States.
| | - Harold W Horowitz
- Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, United States.
| | | | - Bobbi S Pritt
- Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, United States.
| | - Daniel J Sexton
- Duke University Medical Center, Durham, NC 27710, United States.
| | - Gregory A Storch
- Washington University School of Medicine, 425 South Euclid Avenue, St. Louis, MO 63110, United States.
| | - David H Walker
- The University of Texas Medical Branch at Galveston, 301 University Boulevard, Galveston, TX 77555-0609, United States.
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Farooq I, Moriarty TJ. The Impact of Tick-Borne Diseases on the Bone. Microorganisms 2021; 9:663. [PMID: 33806785 PMCID: PMC8005031 DOI: 10.3390/microorganisms9030663] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 03/17/2021] [Accepted: 03/18/2021] [Indexed: 12/21/2022] Open
Abstract
Tick-borne infectious diseases can affect many tissues and organs including bone, one of the most multifunctional structures in the human body. There is a scarcity of data regarding the impact of tick-borne pathogens on bone. The aim of this review was to survey existing research literature on this topic. The search was performed using PubMed and Google Scholar search engines. From our search, we were able to find evidence of eight tick-borne diseases (Anaplasmosis, Ehrlichiosis, Babesiosis, Lyme disease, Bourbon virus disease, Colorado tick fever disease, Tick-borne encephalitis, and Crimean-Congo hemorrhagic fever) affecting the bone. Pathological bone effects most commonly associated with tick-borne infections were disruption of bone marrow function and bone loss. Most research to date on the effects of tick-borne pathogen infections on bone has been quite preliminary. Further investigation of this topic is warranted.
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Affiliation(s)
- Imran Farooq
- Faculty of Dentistry, University of Toronto, Toronto, ON M5G 1G6, Canada;
| | - Tara J. Moriarty
- Faculty of Dentistry, University of Toronto, Toronto, ON M5G 1G6, Canada;
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON M5G 1G6, Canada
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Kuriakose K, Pettit AC, Schmitz J, Moncayo A, Bloch KC. Assessment of Risk Factors and Outcomes of Severe Ehrlichiosis Infection. JAMA Netw Open 2020; 3:e2025577. [PMID: 33201233 PMCID: PMC7672514 DOI: 10.1001/jamanetworkopen.2020.25577] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
IMPORTANCE Ehrlichiosis cases in the US have increased more than 8-fold since 2000. Up to 57% of patients with ehrlichiosis require hospitalization and 11% develop a life-threatening complication; however, risk factors for serious disease are not well documented. OBJECTIVE To examine risk factors associated with severe ehrlichiosis. DESIGN, SETTING, AND PARTICIPANTS An analytic cross-sectional study of patients diagnosed with ehrlichiosis by polymerase chain reaction (PCR) between January 1, 2007, and December 31, 2017, was conducted in a single tertiary-care center in a region endemic for ehrlichiosis. Analysis was performed from February 27, 2018, to September 9, 2020. A total of 407 positive Ehrlichia PCR results were identified from 383 unique patients, with 155 unique patients meeting study criteria. Patients hospitalized at other institutions who had a positive Ehrlichia PCR performed as a reference test (n = 222) were excluded as no clinical data were available. Electronic medical record review was performed to collect demographic, clinical, laboratory, treatment, and outcomes data. Cases were excluded when there were insufficient clinical data to assess the severity of illness (n = 3) and when the clinical illness did not meet the case definition for ehrlichiosis (n = 3). EXPOSURES Date of presentation, onset of symptoms, date of PCR testing, date of treatment initiation, site of care, age, birth sex, race/ethnicity, Charlson Comorbidity Index, trimethoprim with sulfamethoxazole use within the prior 2 weeks, and immunosuppression. MAIN OUTCOMES AND MEASURES Requirement for intensive care unit (ICU) admission. RESULTS Of the 155 patients who met inclusion criteria, 99 patients (63.9%) were men, and 145 patients (93.5%) identified as non-Hispanic White; median age was 50 years (interquartile range, 23-64 years). Intensive care unit admission was indicated in 43 patients (27.7%), 94 patients (60.6%) were hospitalized on general medical floors, and 18 patients (11.6%) received care as outpatients. In adjusted analysis, time to treatment initiation was independently associated with an increased risk for ICU admission (adjusted prevalence ratio [aPR], 1.09; 95% CI, 1.04-1.14; P < .001). Documentation of tick exposure was independently associated with a decreased risk for ICU admission (aPR, 0.54; 95% CI, 0.34-0.86; P = .01). There appeared to be a nonsignificant change toward a decreased need for ICU care among immunosuppressed persons (aPR, 0.51; 95% CI, 0.26-1.00; P = .05). CONCLUSIONS AND RELEVANCE This study suggests that delay in initiation of doxycycline therapy is a significant factor associated with severe ehrlichiosis. Increased recognition of infection by front-line clinicians to promote early treatment may improve outcomes associated with this increasingly common and life-threatening infection.
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Affiliation(s)
- Kevin Kuriakose
- Section of Infectious Disease, Renown Health, Reno, Nevada
- Department of Medicine, School of Medicine, University of Nevada, Reno
| | - April C. Pettit
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jonathan Schmitz
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Abelardo Moncayo
- Vector-Borne Disease Section, Tennessee Department of Health, Nashville
- Department of Health Policy, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Karen C. Bloch
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of Health Policy, Vanderbilt University Medical Center, Nashville, Tennessee
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Green RS, Izac JR, Naimi WA, O'Bier N, Breitschwerdt EB, Marconi RT, Carlyon JA. Ehrlichia chaffeensis EplA Interaction With Host Cell Protein Disulfide Isomerase Promotes Infection. Front Cell Infect Microbiol 2020; 10:500. [PMID: 33072622 PMCID: PMC7538545 DOI: 10.3389/fcimb.2020.00500] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 08/11/2020] [Indexed: 12/19/2022] Open
Abstract
Ehrlichia chaffeensis is an obligate intracellular bacterium that invades monocytes to cause the emerging and potentially severe disease, monocytic ehrlichiosis. Ehrlichial invasion of host cells, a process that is essential for the bacterium's survival and pathogenesis, is incompletely understood. In this study, we identified ECH_0377, henceforth designated as EplA (E. chaffeensis PDI ligand A) as an E. chaffeensis adhesin that interacts with host cell protein disulfide isomerase (PDI) to mediate bacterial entry into host cells. EplA is an outer membrane protein that E. chaffeensis expresses during growth in THP-1 monocytic cells. Canine sera confirmed to be positive for exposure to Ehrlichia spp. recognized recombinant EplA, indicating that it is expressed during infection in vivo. EplA antiserum inhibited the bacterium's ability to infect monocytic cells. The EplA-PDI interaction was confirmed via co-immunoprecipitation. Treating host cell surfaces with antibodies that inhibit PDI and/or thioredoxin-1 thiol reductase activity impaired E. chaffeensis infection. Chemical reduction of host cell surfaces, but not bacterial surfaces with tris(2-carboxyethyl)phosphine (TCEP) restored ehrlichial infectivity in the presence of the PDI-neutralizing antibody. Antisera specific for EplA C-terminal residues 95-104 (EplA95−104) or outer membrane protein A amino acids 53-68 (OmpA53−68) reduced E. chaffeensis infection of THP-1 cells. Notably, TCEP rescued ehrlichial infectivity of bacteria that had been treated with anti-EplA95−104, but not anti-EcOmpA53−68. These results demonstrate that EplA contributes to E. chaffeensis infection of monocytic cells by engaging PDI and exploiting the enzyme's reduction of host cell surface disulfide bonds in an EplA C-terminus-dependent manner and identify EplA95−104 and EcOmpA53−68 as novel ehrlichial receptor binding domains.
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Affiliation(s)
- Ryan S Green
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, United States
| | - Jerilyn R Izac
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, United States
| | - Waheeda A Naimi
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, United States
| | - Nathaniel O'Bier
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, United States
| | - Edward B Breitschwerdt
- Department of Clinical Sciences and the Intracellular Pathogens Research Laboratory, Comparative Medicine Institute, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States
| | - Richard T Marconi
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, United States
| | - Jason A Carlyon
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, School of Medicine, Richmond, VA, United States
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Optimization and Evaluation of a Multiplex Quantitative PCR Assay for Detection of Nucleic Acids in Human Blood Samples from Patients with Spotted Fever Rickettsiosis, Typhus Rickettsiosis, Scrub Typhus, Monocytic Ehrlichiosis, and Granulocytic Anaplasmosis. J Clin Microbiol 2020; 58:JCM.01802-19. [PMID: 32493778 DOI: 10.1128/jcm.01802-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 05/25/2020] [Indexed: 01/09/2023] Open
Abstract
Spotted fever group rickettsioses (SFGR), typhus group rickettsioses (TGR), scrub typhus (caused by Orientia tsutsugamushi), ehrlichiosis, and anaplasmosis often present as undifferentiated fever but are not treated by agents (penicillins and cephalosporins) typically used for acute febrile illness. Inability to diagnose these infections when the patient is acutely ill leads to excess morbidity and mortality. Failure to confirm these infections retrospectively if a convalescent blood sample is not obtained also impairs epidemiologic and clinical research. We designed a multiplex real-time quantitative PCR (qPCR) assay to detect SFGR, TGR, O. tsutsugamushi, and infections caused by Anaplasma phagocytophilum and Ehrlichia chaffeensis with the ompA, 17-kDa surface antigen gene, tsa56, msp2 (p44), and vlpt gene targets, respectively. Analytical sensitivity was ≥2 copies/μl (linear range, 2 to 2 × 105) and specificity was 100%. Clinical sensitivities for SFGR, TGR, and O. tsutsugamushi were 25%, 20%, and 27%, respectively, and specificities were 98%, 99%, and 100%, respectively. Clinical sensitivities for A. phagocytophilum and E. chaffeensis were 93% and 84%, respectively, and specificities were 99% and 98%, respectively. This multiplex qPCR assay could support early clinical diagnosis and treatment, confirm acute infections in the absence of a convalescent-phase serum sample, and provide the high-throughput testing required to support large clinical and epidemiologic studies. Because replication of SFGR and TGR in endothelial cells results in very low bacteremia, optimal sensitivity of qPCR for these rickettsioses will require use of larger volumes of input DNA, which could be achieved by improved extraction of DNA from blood and/or extraction of DNA from a larger initial volume of blood.
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Kunnumpurath A, Kamoga GR. Ehrlichiosis-Induced Atrial Flutter: An Unusual Cause of Atrial Flutter. J Investig Med High Impact Case Rep 2020; 8:2324709620950128. [PMID: 32787462 PMCID: PMC7427037 DOI: 10.1177/2324709620950128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tick-borne illness has been increasingly on the rise, since the first human case was reported in the late 1980s. Ehrlichia chaffeensis is one of the most common reported causes of tick-borne illness, particularly in the southern states of the United States. The clinical picture presents as a paradigm to the clinician, often missing the diagnosis without an appropriate history being taken and sometimes mistreated for other conditions. With the number of cases on the rise, new manifestations and clinical presentations due to E chaffeensis continue to be reported. Our case report is one such case in a 46-year-old male from Arkansas, with known exposure to multiple tick bites who presented with classical symptoms and laboratory values of tick-borne illness leading to atrial flutter. This unusual manifestation of atrial flutter due to tick-borne illness is rare and poorly understood. Further studies on tick-borne illness due to E chaffeensis may be needed to understand the systemic causes of the bacteria. In addition, in our case report, we bring to attention the standard presentation (symptoms, signs, and laboratory values) of tick-borne illness due to E chaffeensis along with the current standard for diagnosis and treatment.
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Torina A, Villari S, Blanda V, Vullo S, La Manna MP, Shekarkar Azgomi M, Di Liberto D, de la Fuente J, Sireci G. Innate Immune Response to Tick-Borne Pathogens: Cellular and Molecular Mechanisms Induced in the Hosts. Int J Mol Sci 2020; 21:ijms21155437. [PMID: 32751625 PMCID: PMC7432002 DOI: 10.3390/ijms21155437] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/28/2020] [Accepted: 07/29/2020] [Indexed: 12/11/2022] Open
Abstract
Many pathogens are transmitted by tick bites, including Anaplasma spp., Ehrlichia spp., Rickettsia spp., Babesia and Theileria sensu stricto species. These pathogens cause infectious diseases both in animals and humans. Different types of immune effector mechanisms could be induced in hosts by these microorganisms, triggered either directly by pathogen-derived antigens or indirectly by molecules released by host cells binding to these antigens. The components of innate immunity, such as natural killer cells, complement proteins, macrophages, dendritic cells and tumor necrosis factor alpha, cause a rapid and intense protection for the acute phase of infectious diseases. Moreover, the onset of a pro-inflammatory state occurs upon the activation of the inflammasome, a protein scaffold with a key-role in host defense mechanism, regulating the action of caspase-1 and the maturation of interleukin-1β and IL-18 into bioactive molecules. During the infection caused by different microbial agents, very similar profiles of the human innate immune response are observed including secretion of IL-1α, IL-8, and IFN-α, and suppression of superoxide dismutase, IL-1Ra and IL-17A release. Innate immunity is activated immediately after the infection and inflammasome-mediated changes in the pro-inflammatory cytokines at systemic and intracellular levels can be detected as early as on days 2–5 after tick bite. The ongoing research field of “inflammasome biology” focuses on the interactions among molecules and cells of innate immune response that could be responsible for triggering a protective adaptive immunity. The knowledge of the innate immunity mechanisms, as well as the new targets of investigation arising by bioinformatics analysis, could lead to the development of new methods of emergency diagnosis and prevention of tick-borne infections.
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Affiliation(s)
- Alessandra Torina
- Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90100 Palermo, Italy; (A.T.); (S.V.); (S.V.)
| | - Sara Villari
- Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90100 Palermo, Italy; (A.T.); (S.V.); (S.V.)
| | - Valeria Blanda
- Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90100 Palermo, Italy; (A.T.); (S.V.); (S.V.)
- Correspondence:
| | - Stefano Vullo
- Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90100 Palermo, Italy; (A.T.); (S.V.); (S.V.)
| | - Marco Pio La Manna
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (M.S.A.); (D.D.L.); (G.S.)
| | - Mojtaba Shekarkar Azgomi
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (M.S.A.); (D.D.L.); (G.S.)
| | - Diana Di Liberto
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (M.S.A.); (D.D.L.); (G.S.)
| | - José de la Fuente
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005 Ciudad Real, Spain;
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Guido Sireci
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (M.S.A.); (D.D.L.); (G.S.)
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Affiliation(s)
- Jennifer S Read
- Department of Pediatrics, University of Vermont Medical Center, Burlington, VT.,Infectious Disease Epidemiology, Vermont Department of Health, Burlington, VT
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Seasonality and trends in incidence of human ehrlichiosis in two Missouri ecoregions. Epidemiol Infect 2019; 147:e123. [PMID: 30868997 PMCID: PMC6518481 DOI: 10.1017/s0950268818003448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Ehrlichiosis is a zoonotic illness caused by Ehrlichia pathogens transmitted by ticks. Case data from 1999 to 2015, provided by the Missouri Department of Health and Senior Services (DHSS), were used to compare the seasonality and the change in incidence over time of ehrlichiosis infection in two Missouri ecoregions, Eastern Temperate Forest (ETF) and Great Plains (GP). Although the number of cases has increased over time in both ecoregions, the rate of change was significantly faster in ETF region. There was no significant difference in seasonality of ehrlichiosis between ecoregions. In Missouri, the estimated ehrlichiosis season begins, on average, in mid-March, peaks in June, and concludes in mid-October. Our results show that the exposure and risk season for ehrlichiosis in Missouri is at least 7 months long.
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Khamesipour F, Dida GO, Anyona DN, Razavi SM, Rakhshandehroo E. Tick-borne zoonoses in the Order Rickettsiales and Legionellales in Iran: A systematic review. PLoS Negl Trop Dis 2018; 12:e0006722. [PMID: 30204754 PMCID: PMC6181433 DOI: 10.1371/journal.pntd.0006722] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 10/11/2018] [Accepted: 07/27/2018] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Tick-borne zoonoses in the Order Rickettsiales and Legionellales cause infections that often manifest as undifferentiated fevers that are not easy to distinguish from other causes of acute febrile illnesses clinically. This is partly attributed to difficulty in laboratory confirmation since convalescent sera, specific diagnostic reagents, and the required expertise may not be readily available. As a result, a number of tick-borne zoonoses are underappreciated resulting in unnecessary morbidity, mortality and huge economic loses. In Iran, a significant proportion of human infectious diseases are tick-borne, with anecdotal evidence suggesting that tick-borne zoonoses are widespread but underreported in the country. Epidemiological review is therefore necessary to aid in the effective control and prevention of tick-borne zonooses in Iran. The aim of this review is to provide an in-depth and comprehensive overview of anaplasmosis, ehrlichiosis, spotted fever group rickettsioses and coxiellosis in Iran. METHODS Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, all relevant publications on tick-borne zoonoses in the Order Rickettsiales and Legionellales in Iran were searched using a number of search terms. The search was confined to authentic resources from repositories of popular data bases among them PubMed, Web of Science, Google Scholar, Science Direct, SpringerLink and SCOPUS. The search items included peer reviewed journals, books and book chapters published between 1996 and 2017. RESULTS A total of 1 205 scientific publications and reports were sourced, of which 63 met the search criteria and were reviewed. Of the 63 articles reviewed, 36 (57.1%) reported on coxiellosis, 15 (23.8%) on anaplasmosis, 11 (17.5%) on ehrlichiosis and 1(1.6%) on spotted fever group rickettsiae in a large scale study involving four countries, among them Iran. The existence of tick-borne pathogens in the Order Rickettsiales and Legionellales was confirmed by molecular, serological and microscopic techniques conducted on samples obtained from sheep, cattle, goats, camels, poultry, animal products (milk and eggs), dogs, ticks and even human subjects in different parts of the country; pointing to a countrywide distribution. DISCUSSION Based on the review, coxiellosis, anaplasmosis, ehrlichiosis, and SFG rickettsiae can be categorized as emerging tick-borne zoonotic diseases in Iran given the presence of their causiative agents (C. burnetii, A. phagocytophilum, A. marginale, A. bovis, A. ovis, A. central, E. canis, E. ewingii, E. chaffeensis and R. conorii) collectively reported in a variety of domestic animals, animal products, arthropods and human beings drawn from 22 provinces in Iran. CONCLUSION Given the asymptomatic nature of some of these zoonoses, there is a high likelihood of silent transmission to humans in many parts of the country, which should be considered a public health concern. Presently, information on the transmission intensity of tick-borne zoonoses caused by pathogens in the Order Rickettsiales and Legionellales to humans and its public health impact in Iran is scanty.
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Affiliation(s)
- Faham Khamesipour
- Cellular and Molecular Research Centre, Sabzevar University of Medical Sciences, Sabzevar, Iran
- Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
| | - Gabriel O. Dida
- School of Public Health and Community Development, Maseno University, Maseno, Kenya
- Department of Community and Public Health, Technical University of Kenya, Nairobi, Kenya
| | - Douglas N. Anyona
- School of Environment and Earth Sciences, Maseno University, Maseno, Kenya
| | - S. Mostafa Razavi
- Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
| | - Ehsan Rakhshandehroo
- Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
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Klema VJ, Sepuru KM, Füllbrunn N, Farris TR, Dunphy PS, McBride JW, Rajarathnam K, Choi KH. Ehrlichia chaffeensis TRP120 nucleomodulin binds DNA with disordered tandem repeat domain. PLoS One 2018; 13:e0194891. [PMID: 29641592 PMCID: PMC5895000 DOI: 10.1371/journal.pone.0194891] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/12/2018] [Indexed: 12/21/2022] Open
Abstract
Ehrlichia chaffeensis, the causative agent of human monocytotropic ehrlichiosis, secretes several effector proteins that bind host DNA to modulate host gene expression. The tandem repeat protein 120 (TRP120), one of the largest effector proteins, has four nearly identical tandem repeat (TR) regions that each consists of 80 amino acids. In addition to playing a role in ehrlichial binding and internalization, TRP120 translocates to the host nucleus where it is thought to function as a transcription factor that modulates gene expression. However, sequence analysis of TRP120 does not identify the presence of DNA-binding or trans-activation domains typical of classical eukaryotic transcription factors. Thus, the mechanism by which TRP120 binds DNA and modulates gene expression remains elusive. Herein, we expressed the TR regions of the TRP120 protein, and characterized its solution structure and ability to bind DNA. TRP120, expressed as either a one or two TR repeat, is a monomer in solution, and is mostly disordered as determined by circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy. Using NMR spectroscopy, we further show that the 1 TR construct selectively binds GC-rich DNA. Although low pH was required for TRP120 TR-DNA interaction, acidic pH alone does not induce any significant structural changes in the TR region. This suggests that TRP120 folds into an ordered structure upon forming a protein-DNA complex, and thus folding of TRP120 TR is coupled with DNA binding.
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Affiliation(s)
- Valerie J. Klema
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Krishna Mohan Sepuru
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Nadia Füllbrunn
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Tierra R. Farris
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Paige S. Dunphy
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jere W. McBride
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Krishna Rajarathnam
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Kyung H. Choi
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail:
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Reller ME, Dumler JS. Development and Clinical Validation of a Multiplex Real-Time Quantitative PCR Assay for Human Infection by Anaplasma phagocytophilum and Ehrlichia chaffeensis. Trop Med Infect Dis 2018; 3:tropicalmed3010014. [PMID: 30274412 PMCID: PMC6136628 DOI: 10.3390/tropicalmed3010014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 01/19/2018] [Accepted: 01/21/2018] [Indexed: 11/16/2022] Open
Abstract
Background: Human granulocytic anaplasmosis (HGA), caused by Anaplasma phagocytophilum, and human monocytic ehrlichiosis (HME), caused by Ehrlichia chaffeensis, often present as undifferentiated fever but are not treated by typical empiric regimens for acute febrile illness. Their role as agents of vector-borne febrile disease in tropical regions is more poorly studied than for other rickettsial infections. Limitations in diagnosis have impaired epidemiologic and clinical research and needless morbidity and mortality occur due to untreated illness. Methods: We designed and clinically validated a multiplex real-time quantitative PCR assay for Anaplasma phagocytophilum and Ehrlichia chaffeensis using samples confirmed by multiple gold-standard methods. Results: Clinical sensitivity and specificity for A. phagocytophilum were 100% (39/39) and 100% (143/143), respectively, and for E. chaffeensis 95% (20/21) and 99% (159/161), respectively. Conclusions: These assays could support early diagnosis and treatment as well as the high-throughput testing required for large epidemiologic studies.
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Affiliation(s)
- Megan E Reller
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA.
- Duke Hubert-Yeargan Center for Global Health, Durham, NC 27708, USA.
- Duke Global Health Institute, Durham, NC 27710, USA.
| | - J Stephen Dumler
- Joint Departments of Pathology, F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, Walter Reed National Military Medical Center, Joint Pathology Center, Bethesda, MD 20814, USA.
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Egizi A, Fefferman NH, Jordan RA. Relative Risk for Ehrlichiosis and Lyme Disease in an Area Where Vectors for Both Are Sympatric, New Jersey, USA. Emerg Infect Dis 2017; 23. [DOI: 10.3201/eid2306.160528] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Abstract
Human ehrlichiosis and anaplasmosis are acute febrile tick-borne infectious diseases caused by various members from the genera Ehrlichia and Anaplasma. Ehrlichia chaffeensis is the major etiologic agent of human monocytotropic ehrlichiosis (HME), while Anaplasma phagocytophilum is the major cause of human granulocytic anaplasmosis (HGA). The clinical manifestations of HME and HGA ranges from subclinical to potentially life-threatening diseases associated with multi-organ failure. Macrophages and neutrophils are the major target cells for Ehrlichia and Anaplasma, respectively. The threat to public health is increasing with newly emerging ehrlichial and anaplasma agents, yet vaccines for human ehrlichioses and anaplasmosis are not available, and therapeutic options are limited. This article reviews recent advances in the understanding of HME and HGA.
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Abstract
It was widely believed in the late 1960s that infectious diseases had been conquered by vaccines and antibiotics and humans were no longer under threat by microbial pathogens. Yet, since that time more than 60 pathogens have been discovered that can cause serious emerging infectious diseases. Molecular methods have played critical roles in the discovery, monitoring, and clinical diagnostics of emerging pathogens. In this chapter, we present well-recognized emerging pathogens. We provide examples of the utility of molecular assays in research and clinical care of emerging infectious diseases. We also discuss some theoretical and practical limitations of molecular tests and the future prospects of expanding molecular diagnostics for emerging pathogens based on new advances of knowledge and technologies.
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Ehrlichioses: An Important One Health Opportunity. Vet Sci 2016; 3:vetsci3030020. [PMID: 29056728 PMCID: PMC5606584 DOI: 10.3390/vetsci3030020] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 08/23/2016] [Accepted: 08/25/2016] [Indexed: 12/13/2022] Open
Abstract
Ehrlichioses are caused by obligately intracellular bacteria that are maintained subclinically in a persistently infected vertebrate host and a tick vector. The most severe life-threatening illnesses, such as human monocytotropic ehrlichiosis and heartwater, occur in incidental hosts. Ehrlichia have a developmental cycle involving an infectious, nonreplicating, dense core cell and a noninfectious, replicating reticulate cell. Ehrlichiae secrete proteins that bind to host cytoplasmic proteins and nuclear chromatin, manipulating the host cell environment to their advantage. Severe disease in immunocompetent hosts is mediated in large part by immunologic and inflammatory mechanisms, including overproduction of tumor necrosis factor α (TNF-α), which is produced by CD8 T lymphocytes, and interleukin-10 (IL-10). Immune components that contribute to control of ehrlichial infection include CD4 and CD8 T cells, natural killer (NK) cells, interferon-γ (IFN-γ), IL-12, and antibodies. Some immune components, such as TNF-α, perforin, and CD8 T cells, play both pathogenic and protective roles. In contrast with the immunocompetent host, which may die with few detectable organisms owing to the overly strong immune response, immunodeficient hosts die with overwhelming infection and large quantities of organisms in the tissues. Vaccine development is challenging because of antigenic diversity of E. ruminantium, the necessity of avoiding an immunopathologic response, and incomplete knowledge of the protective antigens.
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Lina TT, Farris T, Luo T, Mitra S, Zhu B, McBride JW. Hacker within! Ehrlichia chaffeensis Effector Driven Phagocyte Reprogramming Strategy. Front Cell Infect Microbiol 2016; 6:58. [PMID: 27303657 PMCID: PMC4885862 DOI: 10.3389/fcimb.2016.00058] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 05/17/2016] [Indexed: 01/02/2023] Open
Abstract
Ehrlichia chaffeensis is a small, gram negative, obligately intracellular bacterium that preferentially infects mononuclear phagocytes. It is the etiologic agent of human monocytotropic ehrlichiosis (HME), an emerging life-threatening tick-borne zoonosis. Mechanisms by which E. chaffeensis establishes intracellular infection, and avoids host defenses are not well understood, but involve functionally relevant host-pathogen interactions associated with tandem and ankyrin repeat effector proteins. In this review, we discuss the recent advances in our understanding of the molecular and cellular mechanisms that underlie Ehrlichia host cellular reprogramming strategies that enable intracellular survival.
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Affiliation(s)
- Taslima T Lina
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Tierra Farris
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Tian Luo
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Shubhajit Mitra
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Bing Zhu
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Jere W McBride
- Department of Pathology, University of Texas Medical BranchGalveston, TX, USA; Department of Microbiology and Immunology, University of Texas Medical BranchGalveston, TX, USA; Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical BranchGalveston, TX, USA; Sealy Center for Vaccine Development, University of Texas Medical BranchGalveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical BranchGalveston, TX, USA
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Biggs HM, Behravesh CB, Bradley KK, Dahlgren FS, Drexler NA, Dumler JS, Folk SM, Kato CY, Lash RR, Levin ML, Massung RF, Nadelman RB, Nicholson WL, Paddock CD, Pritt BS, Traeger MS. Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever and Other Spotted Fever Group Rickettsioses, Ehrlichioses, and Anaplasmosis - United States. MMWR Recomm Rep 2016; 65:1-44. [PMID: 27172113 DOI: 10.15585/mmwr.rr6502a1] [Citation(s) in RCA: 303] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Tickborne rickettsial diseases continue to cause severe illness and death in otherwise healthy adults and children, despite the availability of low-cost, effective antibacterial therapy. Recognition early in the clinical course is critical because this is the period when antibacterial therapy is most effective. Early signs and symptoms of these illnesses are nonspecific or mimic other illnesses, which can make diagnosis challenging. Previously undescribed tickborne rickettsial diseases continue to be recognized, and since 2004, three additional agents have been described as causes of human disease in the United States: Rickettsia parkeri, Ehrlichia muris-like agent, and Rickettsia species 364D. This report updates the 2006 CDC recommendations on the diagnosis and management of tickborne rickettsial diseases in the United States and includes information on the practical aspects of epidemiology, clinical assessment, treatment, laboratory diagnosis, and prevention of tickborne rickettsial diseases. The CDC Rickettsial Zoonoses Branch, in consultation with external clinical and academic specialists and public health professionals, developed this report to assist health care providers and public health professionals to 1) recognize key epidemiologic features and clinical manifestations of tickborne rickettsial diseases, 2) recognize that doxycycline is the treatment of choice for suspected tickborne rickettsial diseases in adults and children, 3) understand that early empiric antibacterial therapy can prevent severe disease and death, 4) request the appropriate confirmatory diagnostic tests and understand their usefulness and limitations, and 5) report probable and confirmed cases of tickborne rickettsial diseases to public health authorities.
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Affiliation(s)
- Holly M Biggs
- National Center for Emerging and Zoonotic Infectious Diseases, CDC, Atlanta, Georgia
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Abstract
PURPOSE To describe a case of posterior uveitis with retinal vasculitis related to Ehrlichia exposure. PATIENTS AND METHODS Single case report of a 68-year-old woman with posterior uveitis, steroid-induced glaucoma, and retinal holes. RESULTS Ehrlichia titers were elevated 4-fold (1:256; normal <1:64) with an otherwise normal laboratory workup. The patient's cystoid macular edema responded to sub-Tenon's triamcinolone and oral doxycycline. CONCLUSION To our knowledge, this is the first case of posterior uveitis associated with Ehrlichia reported in humans.
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Esteve-Gassent MD, Pérez de León AA, Romero-Salas D, Feria-Arroyo TP, Patino R, Castro-Arellano I, Gordillo-Pérez G, Auclair A, Goolsby J, Rodriguez-Vivas RI, Estrada-Franco JG. Pathogenic Landscape of Transboundary Zoonotic Diseases in the Mexico-US Border Along the Rio Grande. Front Public Health 2014; 2:177. [PMID: 25453027 PMCID: PMC4233934 DOI: 10.3389/fpubh.2014.00177] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Accepted: 09/19/2014] [Indexed: 01/11/2023] Open
Abstract
Transboundary zoonotic diseases, several of which are vector borne, can maintain a dynamic focus and have pathogens circulating in geographic regions encircling multiple geopolitical boundaries. Global change is intensifying transboundary problems, including the spatial variation of the risk and incidence of zoonotic diseases. The complexity of these challenges can be greater in areas where rivers delineate international boundaries and encompass transitions between ecozones. The Rio Grande serves as a natural border between the US State of Texas and the Mexican States of Chihuahua, Coahuila, Nuevo León, and Tamaulipas. Not only do millions of people live in this transboundary region, but also a substantial amount of goods and people pass through it everyday. Moreover, it occurs over a region that functions as a corridor for animal migrations, and thus links the Neotropic and Nearctic biogeographic zones, with the latter being a known foci of zoonotic diseases. However, the pathogenic landscape of important zoonotic diseases in the south Texas-Mexico transboundary region remains to be fully understood. An international perspective on the interplay between disease systems, ecosystem processes, land use, and human behaviors is applied here to analyze landscape and spatial features of Venezuelan equine encephalitis, Hantavirus disease, Lyme Borreliosis, Leptospirosis, Bartonellosis, Chagas disease, human Babesiosis, and Leishmaniasis. Surveillance systems following the One Health approach with a regional perspective will help identifying opportunities to mitigate the health burden of those diseases on human and animal populations. It is proposed that the Mexico-US border along the Rio Grande region be viewed as a continuum landscape where zoonotic pathogens circulate regardless of national borders.
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Affiliation(s)
- Maria Dolores Esteve-Gassent
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
| | | | - Dora Romero-Salas
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Veracruzana, Veracruz, México
| | | | - Ramiro Patino
- Department of Biology, University of Texas-Pan American, Edinburg, TX, USA
| | - Ivan Castro-Arellano
- Department of Biology, College of Science and Engineering, Texas State University, San Marcos, TX, USA
| | - Guadalupe Gordillo-Pérez
- Unidad de Investigación en Enfermedades Infecciosas, Centro Médico Nacional SXXI, IMSS, Distrito Federal, México
| | - Allan Auclair
- Environmental Risk Analysis Systems, Policy and Program Development, Animal and Plant Health Inspection Service, United States Department of Agriculture, Riverdale, MD, USA
| | - John Goolsby
- Cattle Fever Tick Research Laboratory, United States Department of Agriculture, Agricultural Research Service, Edinburg, TX, USA
| | - Roger Ivan Rodriguez-Vivas
- Facultad de Medicina Veterinaria y Zootecnia, Cuerpo Académico de Salud Animal, Universidad Autónoma de Yucatán, Mérida, México
| | - Jose Guillermo Estrada-Franco
- Facultad de Medicina Veterinaria Zootecnia, Centro de Investigaciones y Estudios Avanzados en Salud Animal, Universidad Autónoma del Estado de México, Toluca, México
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Andrić B. Diagnostic Evaluation of <i> Ehrlichia</i> <i>canis</i> Human Infections. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ojmm.2014.42015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Dunphy PS, Luo T, McBride JW. Ehrlichia moonlighting effectors and interkingdom interactions with the mononuclear phagocyte. Microbes Infect 2013; 15:1005-16. [PMID: 24141087 PMCID: PMC3886233 DOI: 10.1016/j.micinf.2013.09.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/27/2013] [Accepted: 09/30/2013] [Indexed: 01/19/2023]
Abstract
Ehrlichia chaffeensis is an obligately intracellular gram negative bacterium with a small genome that thrives in mammalian mononuclear phagocytes by exploiting eukaryotic processes. Herein, we discuss the latest findings on moonlighting tandem repeat protein effectors and their secretion mechanisms, and novel molecular interkingdom interactions that provide insight into the intracellular pathobiology of ehrlichiae.
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Affiliation(s)
- Paige Selvy Dunphy
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555
| | - Tian Luo
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas 77555
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas 77555
- Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas 77555
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas 77555
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Social-ecological factors determine spatial variation in human incidence of tick-borne ehrlichiosis. Epidemiol Infect 2013; 142:1911-24. [DOI: 10.1017/s0950268813002951] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
SUMMARYThe spatial distribution of human cases of tick-borne diseases is probably determined by a combination of biological and socioeconomic factors. A zoonotic tick-borne pathogen, Ehrlichia chaffeensis, is increasing in human incidence in the USA. In this study, the spatial patterns of probable and confirmed E. chaffeensis-associated cases of ehrlichiosis from 2000 to 2011 were investigated at the zip-code level in Missouri. We applied spatial statistics, including global and local regression models, to investigate the biological and socioeconomic factors associated with human incidence. Our analysis confirms that the distribution of ehrlichiosis in Missouri is non-random, with numerous clusters of high incidence. Furthermore, we identified significant, but spatially variable, associations between incidence and both biological and socioeconomic factors, including a positive association with reservoir host density and a negative association with human population density. Improved understanding of local variation in these spatial factors may facilitate targeted interventions by public health authorities.
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31
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Folkema AM, Holman RC, Dahlgren FS, Cheek JE, McQuiston JH. Epidemiology of ehrlichiosis and anaplasmosis among American Indians in the United States, 2000-2007. Am J Trop Med Hyg 2012; 87:529-37. [PMID: 22826495 DOI: 10.4269/ajtmh.2012.12-0060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Ehrlichiosis and anaplasmosis infections among American Indians (AIs) have never been specifically examined, despite high rates of other tick-borne rickettsial diseases among AIs. The epidemiology of ehrlichiosis and anaplasmosis among AIs was analyzed using the National Electronic Telecommunications System for Surveillance (NETSS), Case Report Forms (CRFs), and Indian Health Service (IHS) inpatient and outpatient visits. The 2000-2007 average annual ehrlichiosis and anaplasmosis incidence among AIs reported to NETSS was almost 4-fold lower (4.0/1,000,000) than that using IHS data (14.9). American Indian cases reported from CRFs had a higher proportion of hospitalization (44%) compared with IHS (10%). American Indian incidence of ehrlichiosis and anaplasmosis was higher and showed a different age and geographical distribution than other races. These results highlight the need to improve collaboration between the ehrlichiosis and anaplasmosis surveillance systems for AIs so as to develop interventions that target the unique epidemiology and mitigate the burden of disease among this high-risk population.
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Affiliation(s)
- Arianne M Folkema
- Division of High-Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Centers for Disease Control and Prevention (CDC), United States
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32
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Immunization with Ehrlichia P28 outer membrane proteins confers protection in a mouse model of ehrlichiosis. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 18:2018-25. [PMID: 22030371 DOI: 10.1128/cvi.05292-11] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The obligately intracellular bacterium Ehrlichia chaffeensis that resides in mononuclear phagocytes is the etiologic agent of human monocytotropic ehrlichiosis (HME). HME is an emerging and often life-threatening, tick-transmitted infectious disease in the United States. Effective primary immune responses against Ehrlichia infection involve generation of Ehrlichia-specific gamma interferon (IFN-γ)-producing CD4(+) T cells and cytotoxic CD8(+) T cells, activation of macrophages by IFN-γ, and production of Ehrlichia-specific antibodies of the Th1 isotype. Currently, there are no vaccines available against HME. We evaluated the ability of 28-kDa outer membrane proteins (P28-OMP-1) of the closely related Ehrlichia muris to stimulate long-term protective memory T and B cell responses and confer protection in mice. The spleens of mice vaccinated with E. muris P28-9, P28-12, P28-19, or a mixture of these three P28 proteins (P28s) using a DNA prime-protein boost regimen and challenged with E. muris had significantly lower bacterial loads than the spleens of mock-vaccinated mice. Mice immunized with P28-9, P28-12, P28-19, or the mixture induced Ehrlichia-specific CD4(+) Th1 cells. Interestingly, mice immunized with P28-14, orthologs of which in E. chaffeensis and E. canis are primarily expressed in tick cells, failed to lower the ehrlichial burden in the spleen. Immunization with the recombinant P28-19 protein alone also significantly decreased the bacterial load in the spleen and liver compared to those of the controls. Our study reports, for the first time, the protective roles of the Ehrlichia P28-9 and P28-12 proteins in addition to confirming previous reports of the protective ability of P28-19. Partial protection induced by immunization with P28-9, P28-12, and P28-19 against Ehrlichia was associated with the generation of Ehrlichia-specific cell-mediated and humoral immune responses.
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33
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Vieira RFDC, Biondo AW, Guimarães AMS, Dos Santos AP, Dos Santos RP, Dutra LH, Diniz PPVDP, de Morais HA, Messick JB, Labruna MB, Vidotto O. Ehrlichiosis in Brazil. ACTA ACUST UNITED AC 2011; 20:1-12. [PMID: 21439224 DOI: 10.1590/s1984-29612011000100002] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Accepted: 11/03/2010] [Indexed: 11/21/2022]
Abstract
Ehrlichiosis is a disease caused by rickettsial organisms belonging to the genus Ehrlichia. In Brazil, molecular and serological studies have evaluated the occurrence of Ehrlichia species in dogs, cats, wild animals and humans. Ehrlichia canis is the main species found in dogs in Brazil, although E. ewingii infection has been recently suspected in five dogs. Ehrlichia chaffeensis DNA has been detected and characterized in mash deer, whereas E. muris and E. ruminantium have not yet been identified in Brazil. Canine monocytic ehrlichiosis caused by E. canis appears to be highly endemic in several regions of Brazil, however prevalence data are not available for several regions. Ehrlichia canis DNA also has been detected and molecularly characterized in three domestic cats, and antibodies against E. canis were detected in free-ranging Neotropical felids. There is serological evidence suggesting the occurrence of human ehrlichiosis in Brazil but its etiologic agent has not yet been established. Improved molecular diagnostic resources for laboratory testing will allow better identification and characterization of ehrlichial organisms associated with human ehrlichiosis in Brazil.
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34
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Molecular Approaches to the Diagnosis of Meningitis and Encephalitis. Mol Microbiol 2011. [DOI: 10.1128/9781555816834.ch50] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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35
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Abstract
Human ehrlichiosis and anaplasmosis are acute febrile tick-borne diseases caused by various members of the genera Ehrlichia and Anaplasma (Anaplasmataceae). Human monocytotropic ehrlichiosis has become one of the most prevalent life-threatening tick-borne disease in the United States. Ehrlichiosis and anaplasmosis are becoming more frequently diagnosed as the cause of human infections, as animal reservoirs and tick vectors have increased in number and humans have inhabited areas where reservoir and tick populations are high. Ehrlichia chaffeensis, the etiologic agent of human monocytotropic ehrlichiosis (HME), is an emerging zoonosis that causes clinical manifestations ranging from a mild febrile illness to a fulminant disease characterized by multiorgan system failure. Anaplasma phagocytophilum causes human granulocytotropic anaplasmosis (HGA), previously known as human granulocytotropic ehrlichiosis. This article reviews recent advances in the understanding of ehrlichial diseases related to microbiology, epidemiology, diagnosis, pathogenesis, immunity, and treatment of the 2 prevalent tick-borne diseases found in the United States, HME and HGA.
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36
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Little SE, O'Connor TP, Hempstead J, Saucier J, Reichard MV, Meinkoth K, Meinkoth JH, Andrews B, Ullom S, Ewing SA, Chandrashekar R. Ehrlichia ewingii infection and exposure rates in dogs from the southcentral United States. Vet Parasitol 2010; 172:355-60. [PMID: 20541322 DOI: 10.1016/j.vetpar.2010.05.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Revised: 04/06/2010] [Accepted: 05/05/2010] [Indexed: 11/26/2022]
Abstract
We used PCR and a novel serologic assay to determine infection and exposure rates to Ehrlichia ewingii in dogs from an area of northeast Oklahoma and northwest Arkansas where Amblyomma americanum ticks are abundant. Of 143 dogs assayed, 13 (9.1%) harbored E. ewingii by PCR and 64 (44.8%) had antibodies to E. ewingii detected using a peptide-based microtiter plate ELISA. Dogs were more likely (P=0.001) to be positive by PCR if sampled in August (30.8%) but no association was found between seropositive status and month of collection of sample (P>0.05). Additional testing revealed PCR evidence of Ehrlichia chaffeensis (4/143; 2.8%) and Anaplasma platys (5/143; 3.5%) as well as antibodies reactive to E. chaffeensis (25/143; 17.5%), Ehrlichia canis (2/143; 1.4%), and Anaplasma spp. (8/143; 5.6%). Testing of another 200 dogs from the area revealed additional PCR and/or serologic evidence of E. ewingii, E. canis, E. chaffeensis, and A. platys. None of the 343 dogs evaluated had evidence of Borrelia burgdorferi exposure. These data support the interpretation that E. ewingii may be the primary agent of canine ehrlichiosis in this region, and suggest that diagnostic evaluation of dogs suspected to have a tick-borne disease should include assays targeting this organism.
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Affiliation(s)
- Susan E Little
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA.
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37
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Heise SR, Elshahed MS, Little SE. Bacterial diversity in Amblyomma americanum (Acari: Ixodidae) with a focus on members of the genus Rickettsia. JOURNAL OF MEDICAL ENTOMOLOGY 2010; 47:258-268. [PMID: 20380308 DOI: 10.1603/me09197] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The lone star tick, Amblyomma americanum (Acari: Ixodidae), is commonly reported from people and animals throughout the eastern U.S. and is associated with transmission of a number of emerging diseases. To better define the microbial communities within lone star ticks, 16S rRNA gene based analysis using bacteria-wide primers, followed by sequencing of individual clones (n = 449) was used to identify the most common bacterial operational taxonomic units (OTUs) present within colony-reared and wild A. americanum. The colony-reared ticks contained primarily sequence affiliated with members of the genus Coxiella (89%; 81/91), common endosymbionts of ticks, and Brevibacterium (11%; 10/91). Similarly, analysis of clones from unfed wild lone star ticks revealed that 96.7% (89/92) of all the OTUs identified were affiliated with Coxiella-like endosymbionts, as compared with only 5.1-11.7% (5/98-9/77) of those identified from wild lone star ticks after feeding. In contrast, the proportion of OTUs identified as Rickettsia sp. in wild-caught ticks increased from 2.2% (2/92) before feeding to as high as 46.8% (36/77) after feeding, and all Rickettsia spp. sequences recovered were most similar to those described from the spotted fever group Rickettsia, specifically R. amblyommii and R. massiliae. Additional characterization of the Rickettsiales tick community by polymerase chain reaction, cloning, and sequencing of 17 kDa and gltA genes confirmed these initial findings and suggested that novel Rickettsia spp. are likely present in these ticks. These data provide insight into the overall, as well as the rickettsial community of wild lone star ticks and may ultimately aid in identification of novel pathogens transmitted by A. americanum.
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Affiliation(s)
- Stephanie R Heise
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
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38
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Glaser C, Christie L, Bloch KC. Rickettsial and ehrlichial infections. HANDBOOK OF CLINICAL NEUROLOGY 2010; 96:143-158. [PMID: 20109680 DOI: 10.1016/s0072-9752(09)96010-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Rickettsial diseases represent a clinically homogeneous group of infections characterized by fever, headache myalgias, variable presence of a rash, and a broad spectrum of neurological manifestations. Epidemiological information including time of year, geography, history of arthropod exposure, and animal contact gives important clues to the diagnosis, and should be actively elicited. Abnormalities in hematological indices of liver function tests should also increase suspicion for illness. Delay in initiation of doxycycline therapy while awaiting laboratory confirmation of infection has been associated with progressive neurological impairment and death. Clinicians should maintain a low threshold to initiate empiric therapy for rickettsial diseases in any patient with neurological findings and compatible exposures, signs, or laboratories, as these syndromes represent readily treatable causes of neurological dysfunction.
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Affiliation(s)
- Carol Glaser
- Viral and Rickettsial Disease Laboratory, Richmond, VA, USA.
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39
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Persistent infection contributes to heterologous protective immunity against fatal ehrlichiosis. Infect Immun 2009; 77:5682-9. [PMID: 19805532 DOI: 10.1128/iai.00720-09] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Human monocytotropic ehrlichiosis (HME), an emerging and often life-threatening tick-transmitted disease, is caused by the obligately intracellular bacterium Ehrlichia chaffeensis. HME is modeled in C57BL/6 mice using Ehrlichia muris, which causes persistent infection, and Ixodes ovatus Ehrlichia (IOE), which is either acutely lethal or sublethal depending on the dose and route of inoculation. A persistent primary E. muris infection, but not a sublethal IOE infection, protects mice against an ordinarily lethal secondary IOE challenge. In the present study, we determined the role of persistent infection in maintenance of protective memory immune responses. E. muris-infected mice were treated with doxycycline or left untreated and then challenged with an ordinarily lethal dose of IOE. Compared to E. muris-primed mice treated with doxycycline, untreated mice persistently infected with E. muris had significantly greater numbers of antigen-specific gamma interferon-producing splenic memory T cells, significant expansion of CD4(+) CD25(+) T regulatory cells, and production of transforming growth factor beta1 in the spleen. Importantly, E. muris-primed mice treated with doxycycline showed significantly greater susceptibility to challenge infection with IOE compared to untreated mice persistently infected with E. muris. The study indicated that persistent ehrlichial infection contributes to heterologous protection by stimulating the maintenance of memory T-cell responses.
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40
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Thomas RJ, Stephen Dumler J, Carlyon JA. Current management of human granulocytic anaplasmosis, human monocytic ehrlichiosis and Ehrlichia ewingii ehrlichiosis. Expert Rev Anti Infect Ther 2009; 7:709-22. [PMID: 19681699 PMCID: PMC2739015 DOI: 10.1586/eri.09.44] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Anaplasma phagocytophilum, Ehrlichia chaffeensis and Ehrlichia ewingii are emerging tick-borne pathogens and are the causative agents of human granulocytic anaplasmosis, human monocytic ehrlichiosis and E. ewingii ehrlichiosis, respectively. Collectively, these are referred to as human ehrlichioses. These obligate intracellular bacterial pathogens of the family Anaplasmataceae are transmitted by Ixodes spp. or Amblyomma americanum ticks and infect peripherally circulating leukocytes to cause infections that range in clinical spectra from asymptomatic seroconversion to mild, severe or, in rare instances, fatal disease. This review describes: the ecology of each pathogen; the epidemiology, clinical signs and symptoms of the human diseases that each causes; the choice methods for diagnosing and treating human ehrlichioses; recommendations for patient management; and is concluded with suggestions for potential future research.
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Affiliation(s)
- Rachael J Thomas
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - J Stephen Dumler
- Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MA, USA
| | - Jason A Carlyon
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Molecular Medicine Research Building, 1220 East Broad Street, Room 4052, PO Box 980678, Richmond, VA 23298-0678, USA Tel.: +1 804 628 3382 Fax: +1 804 828 9946
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41
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Delos Santos JRC, Oglesbee M, Rikihisa Y, Stich RW. Pathologic evidence of ehrlichiosis in calves inoculated with Ehrlichia chaffeensis. Ann N Y Acad Sci 2009; 1149:103-6. [PMID: 19120184 DOI: 10.1196/annals.1428.068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
An immunocompetent animal disease model based on infection with Ehrlichia chaffeensis would facilitate research toward understanding mechanisms responsible for the broad range of clinical signs associated with human monocytic ehrlichiosis (HME). The adaptability of this model for the experimental feeding of tick species and stages and for testing therapies comparable to those for human diseases are additional advantages of large animal models. Herein, we summarize pathology reports for calves that developed fatal disease after experimental inoculation with E. chaffeensis. Elevated liver enzyme levels and lung pathology among these calves corroborated earlier reports of severe HME. Thus, an experimental disease model based on infection of outbred immunocompetent hosts with E. chaffeensis could be within our grasp for the first time.
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Affiliation(s)
- Jose R C Delos Santos
- Department of Veterinary Preventive Medicine, Ohio State University, Columbus, Ohio, USA
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42
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Walker DH, Paddock CD, Dumler JS. Emerging and re-emerging tick-transmitted rickettsial and ehrlichial infections. Med Clin North Am 2008; 92:1345-61, x. [PMID: 19061755 DOI: 10.1016/j.mcna.2008.06.002] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recently in the field of rickettsiology, an explosion of new isolates of pathogens have received species designation and new disease names, all of which have been relatively neglected by primary care and infectious disease physicians. A broad group of other tick-associated rickettsial and ehrlichial agents of unknown pathogenicity exist (eg, R amblyommii) that may cause confusion in interpreting serologic surveys or a single elevated antibody titer. Rickettsial and ehrlichial diseases are remarkable for their uniform susceptibility to doxycycline but are clinically difficult to distinguish from many viral infections and each another, and therefore misdiagnosis and failure to treat have unfortunate and sometimes tragic outcomes. Globally, many of these bacteria have been named but the genetic differences among them are often small, and many of their clinical manifestations may not be distinguishable diagnostically.
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Affiliation(s)
- David H Walker
- Department of Pathology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0609, USA.
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43
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Tunkel AR, Glaser CA, Bloch KC, Sejvar JJ, Marra CM, Roos KL, Hartman BJ, Kaplan SL, Scheld WM, Whitley RJ. The management of encephalitis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis 2008; 47:303-27. [PMID: 18582201 DOI: 10.1086/589747] [Citation(s) in RCA: 648] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Guidelines for the diagnosis and treatment of patients with encephalitis were prepared by an Expert Panel of the Infectious Diseases Society of America. The guidelines are intended for use by health care providers who care for patients with encephalitis. The guideline includes data on the epidemiology, clinical features, diagnosis, and treatment of many viral, bacterial, fungal, protozoal, and helminthic etiologies of encephalitis and provides information on when specific etiologic agents should be considered in individual patients with encephalitis.
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Affiliation(s)
- Allan R Tunkel
- Dept of Medicine, Monmouth Medical Center, Long Branch, New Jersey 07740, USA.
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44
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Masters EJ, Grigery CN, Masters RW. STARI, or Masters disease: Lone Star tick-vectored Lyme-like illness. Infect Dis Clin North Am 2008; 22:361-76, viii. [PMID: 18452807 DOI: 10.1016/j.idc.2007.12.010] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Lyme-like illness (also known as southern tick-associated rash illness [STARI] or Masters disease) is vectored by the Lone Star tick (Amblyomma americanum). Lyme-like illness lesions, which are similar to the erythema migrans rash of Lyme disease, tend to have lymphocytic dermal infiltrates. With the exception of Borrelia lonestari, the possible causative agent or agents of Lyme-like illness have not been cultured. More research is needed to fully understand this newly recognized zoonosis. Clinicians are encouraged to increase their knowledge and awareness of this Lyme disease mimic.
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45
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Dong J, Olano JP, McBride JW, Walker DH. Emerging pathogens: challenges and successes of molecular diagnostics. J Mol Diagn 2008; 10:185-97. [PMID: 18403608 PMCID: PMC2329782 DOI: 10.2353/jmoldx.2008.070063] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
More than 50 emerging and reemerging pathogens have been identified during the last 40 years. Until 1992 when the Institute of Medicine issued a report that defined emerging infectious diseases, medicine had been complacent about such infectious diseases despite the alarm bells of infections with human immunodeficiency virus. Molecular tools have proven useful in discovering and characterizing emerging viruses and bacteria such as Sin Nombre virus (hantaviral pulmonary syndrome), hepatitis C virus, Bartonella henselae (cat scratch disease, bacillary angiomatosis), and Anaplasma phagocytophilum (human granulocytotropic anaplasmosis). The feasibility of applying molecular diagnostics to dangerous, fastidious, and uncultivated agents for which conventional tests do not yield timely diagnoses has achieved proof of concept for many agents, but widespread use of cost-effective, validated commercial assays has yet to occur. This review presents representative emerging viral respiratory infections, hemorrhagic fevers, and hepatitides, as well as bacterial and parasitic zoonotic, gastrointestinal, and pulmonary infections. Agent characteristics, epidemiology, clinical manifestations, and diagnostic methods are tabulated for another 22 emerging viruses and five emerging bacteria. The ongoing challenge to the field of molecular diagnostics is to apply contemporary knowledge to facilitate agent diagnosis as well as to further discoveries of novel pathogens.
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Affiliation(s)
- Jianli Dong
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
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46
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Delos Santos JRC, Boughan K, Bremer WG, Rizzo B, Schaefer JJ, Rikihisa Y, Needham GR, Capitini LA, Anderson DE, Oglesbee M, Ewing SA, Stich RW. Experimental infection of dairy calves with Ehrlichia chaffeensis. J Med Microbiol 2008; 56:1660-1668. [PMID: 18033836 DOI: 10.1099/jmm.0.47427-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human monocytic ehrlichiosis (HME) is a zoonotic emerging tick-borne disease with clinical signs that range from mild symptoms to multiple organ failure and death. Ehrlichia chaffeensis, the aetiologic agent of HME, is reported to infect a divergent range of mammals. Although cattle are common hosts of the primary vector of this pathogen, the susceptibility of this host to E. chaffeensis has not been reported to date. This study was undertaken to determine if cattle could provide a useful infection model of E. chaffeensis. Dairy calves were injected with DH82 cells infected with the Arkansas, St Vincent or 91HE17 strain of E. chaffeensis, and monitored for signs of clinical ehrlichiosis and for infection of peripheral blood and ticks by PCR assay. Splenectomized and spleen-intact calves were injected with cryopreserved stabilates of E. chaffeensis-infected DH82 cells for the first experiment. Mild clinical signs were occasionally observed among these calves, and only two blood samples were PCR-positive, while several ticks fed on each calf tested PCR-positive. The second experiment involved injection of normal calves with active cultures of the same E. chaffeensis strains. Interestingly, three of six calves inoculated with active cultures became recumbent and died or had to be euthanized. All of the surviving calves in this experiment tested PCR-positive on multiple dates, but fewer ticks fed on these calves were PCR-positive. These results suggest that a bovine disease model could facilitate the understanding of factors that affect the severity of HME.
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Affiliation(s)
- Jose R C Delos Santos
- Department of Veterinary Preventive Medicine, Ohio State University, Columbus, OH, USA
| | - Kirsten Boughan
- Department of Veterinary Preventive Medicine, Ohio State University, Columbus, OH, USA
| | - William G Bremer
- Department of Veterinary Preventive Medicine, Ohio State University, Columbus, OH, USA
| | - Brian Rizzo
- Department of Veterinary Preventive Medicine, Ohio State University, Columbus, OH, USA
| | - John J Schaefer
- Department of Entomology, Ohio State University, Columbus, OH, USA
| | - Yasuko Rikihisa
- Department of Veterinary Biosciences, Ohio State University, Columbus, OH, USA
| | - Glen R Needham
- Department of Entomology, Ohio State University, Columbus, OH, USA
| | - L A Capitini
- University Laboratory Animal Resources, Ohio State University, Columbus, OH, USA
| | - David E Anderson
- Department of Veterinary Clinical Sciences, Ohio State University, Columbus, OH, USA
| | - Michael Oglesbee
- Department of Veterinary Biosciences, Ohio State University, Columbus, OH, USA
| | - S A Ewing
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK, USA
| | - Roger W Stich
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO, USA
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47
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Assi MA, Yao JDC, Walker RC. Lyme disease followed by human granulocytic anaplasmosis in a kidney transplant recipient. Transpl Infect Dis 2007; 9:66-72. [PMID: 17313478 DOI: 10.1111/j.1399-3062.2006.00177.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We report the case of a kidney transplant recipient who developed Lyme disease, followed by human granulocytic anaplasmosis (HGA) 3 years later. A review of all previously published cases of Lyme disease (3 cases), HGA (5 cases), and human monocytic ehrlichiosis (HME) (5 cases) in transplant recipients is presented. Manifestations of the cases reviewed were similar to those of non-transplant patients. There appeared to be no obvious correlation between immunosuppression and the occurrence of the illness in the transplant recipients. Serologic testing failed to make a diagnosis in 1 patient with HME in the literature and in our patient with HGA, but molecular tests established the diagnosis in both cases. Tandem infection was observed in 1 patient with two episodes of HME 2 years apart. A high index of suspicion for tick-borne illnesses and appropriate prevention measures are needed for transplant patients with epidemiologic risk factors.
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Affiliation(s)
- M A Assi
- Division of Infectious Diseases, Department of Internal Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905-0002, USA
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Dumler JS, Madigan JE, Pusterla N, Bakken JS. Ehrlichioses in humans: epidemiology, clinical presentation, diagnosis, and treatment. Clin Infect Dis 2007; 45 Suppl 1:S45-51. [PMID: 17582569 DOI: 10.1086/518146] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Human ehrlichioses are emerging tickborne infections. "Human ehrlichiosis" describes infections with at least 5 separate obligate intracellular bacteria in 3 genera in the family Anaplasmataceae. Since 1986, these agents and infections (human monocytic ehrlichiosis [HME], caused by Ehrlichia chaffeensis; human granulocytic anaplasmosis [HGA], caused by Anaplasma phagocytophilum; and human ewingii ehrlichiosis, caused by Ehrlichia ewingii) are the causes of most human ehrlichioses. Their prevalence and incidence are increasing where the appropriate tick vectors are found. The diseases generally present as undifferentiated fever, but thrombocytopenia, leukopenia, and increased serum transaminase activities are important laboratory features. Despite clinical similarities, each disease has unique features: a greater severity and a higher case-fatality rate for HME and a higher prevalence of opportunistic infections for HGA. Once an ehrlichiosis is suspected on historical and clinical grounds, doxycycline treatment should be initiated concurrently with attempts at etiologic confirmation using laboratory methods such as blood smear examination, polymerase chain reaction, culture, and serologic tests.
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Affiliation(s)
- J Stephen Dumler
- Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Bloch KC, Glaser C. Diagnostic approaches for patients with suspected encephalitis. Curr Infect Dis Rep 2007; 9:315-22. [PMID: 17618552 DOI: 10.1007/s11908-007-0049-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Encephalitis represents a diagnostic challenge, with an infectious etiology identified in only 40% to 70% of cases. More than 100 agents have been either definitively or anecdotally associated with encephalitis. Important considerations for diagnosis include selection of the appropriate clinical specimen (serum vs cerebrospinal fluid), determining the most sensitive diagnostic assay (serology vs polymerase chain reaction), and assessing causality when an organism is identified outside of the central nervous system (eg, a positive nasal swab for influenza). This review aims to provide an evidence-based, clinically relevant approach to the diagnostic evaluation of patients presenting with encephalitis, focusing on the most common or important causes in the immunocompetent host. Diagnostic issues associated with encephalitis due to herpes-group viruses, arboviruses (including West Nile virus), rickettsiae, bartonella, enteroviruses, and rabies are discussed in-depth. Diagnostic testing should be individualized based on clinical presentation and epidemiology.
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Affiliation(s)
- Karen C Bloch
- Vanderbilt University Medical Center, A-2200 Medical Center North, Nashville, TN 27232-2582, USA.
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Miura K, Rikihisa Y. Virulence potential of Ehrlichia chaffeensis strains of distinct genome sequences. Infect Immun 2007; 75:3604-13. [PMID: 17438035 PMCID: PMC1932932 DOI: 10.1128/iai.02028-06] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Human monocytic ehrlichiosis, one of the most frequent life-threatening tick-borne zoonoses, is caused by Ehrlichia chaffeensis that lacks endotoxin and peptidoglycan. While sequence polymorphisms in several genes in E. chaffeensis strains have been reported, global genomic divergence and biological differences among strains are unknown. The objectives of the present study were to compare the genome sequences of strains of E. chaffeensis and to examine the virulence potentials of the strains with defined genome sequences. Genomic DNA was extracted from purified E. chaffeensis strains Wakulla and Liberty, and comparative genome hybridization was performed using a densely tiled microarray of 147,027 chromosome positions of the E. chaffeensis strain Arkansas genome. The results revealed that 4,663 and 5,325 positions in the chromosomes of strains Wakulla and Liberty, respectively, were different from those in the chromosome of strain Arkansas, including three common major polymorphic chromosomal regions. Of various functional categories, the differences were most concentrated in genes predicted to encode cell envelope proteins. Of all the open reading frames (ORFs), 21 omp-1 (p28 gene) paralogs, nine genes encoding hypothetical proteins, two genes encoding ankyrin repeat proteins, and hemE contained the most differences. Several highly polymorphic ORFs were confirmed by sequencing. When the E. chaffeensis strains were inoculated into severe combined immunodeficiency mice, the order of the severity of clinical signs and the bacterial burden detected in mice was Wakulla > Liberty > Arkansas. Severe diffuse inflammation and granulomatous inflammation were evident in the livers of mice infected with strains Wakulla and Arkansas, respectively, but not in the livers of mice infected with strain Liberty. These results revealed distinct virulence phenotypes of E. chaffeensis strains with defined genome sequences.
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Affiliation(s)
- Koshiro Miura
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH 43210, USA
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