Equine ehrlichiosis in northern California: 49 cases (1968-1981).

Abstract: Case records of horses with equine ehrlichiosis (Ehrlichia equi) at the University of California Veterinary Medical Teaching Hospital and Ackerman Creek Large Animal Clinic were analyzed for evaluation of clinical signs, time of onset, hematologic values, response to treatment, and recovery. Equine ehrlichiosis was found to be seasonal in horses in the foothills of northern California, with higher incidence than reported previously. The horses developed fever, anorexia, depression, limb edema, icterus, and ataxia. Hematologic changes were leukopenia, thrombocytopenia, icterus, anemia, and inclusion bodies in the neutrophils and eosinophils. Diagnosis was made by observing the characteristic inclusion bodies, using a standard Wright's stain. Mortality was low, although complications of opportunistic secondary infection and injury due to ataxia did develop. Treatment with tetracycline resulted in prompt clinical improvement within 24 hours. Chronic cases were not detected. Equine ehrlichiosis should be differentiated from diseases with similar clinical signs including encephalitis, liver disease, purpura hemorrhagica, equine infectious anemia, and equine viral arteritis.
Publication Date: 1987-02-15 PubMed ID: 3558086
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  • Journal Article

Summary

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This research analyzes case records of equine ehrlichiosis in northern California, investigating its symptoms, onset, hematology, treatment response, and recovery. The data suggests that equine ehrlichiosis is a seasonal disease with a higher incidence than previously reported.

Study Overview and Objective

The study primarily focuses on examining the clinical signs, time of onset, hematological alterations, treatment responses, and recovery processes in cases of equine ehrlichiosis, a bacterial infection affecting horses. It leverages case records from the University of California Veterinary Medical Teaching Hospital and Ackerman Creek Large Animal Clinic.

Disease Characteristics

  • The study found that equine ehrlichiosis primarily exhibits seasonal patterns in northern California’s foothills, and its incidence is higher than what was previously reported.
  • Major symptoms of the infection in horses include fever, lack of appetite (anorexia), depression, swelling of the limbs (limb edema), yellowing of the skin, eyes, and gums (icterus), and loss of coordination (ataxia).
  • Key hematological changes mirrored white blood cell reduction (leukopenia), platelet decrease (thrombocytopenia), icterus, anemia, and the presence of inclusion bodies in neutrophils and eosinophils, types of white blood cells.

Diagnosis and Treatment

  • Diagnosis was primarily obtained by observing the characteristic inclusion bodies using a standard Wright’s stain technique.
  • The mortality rate among the affected horses was relatively low. However, complications that included secondary infections due to opportunist pathogens and injuries caused by a loss of coordination were observed.
  • The study found that the administration of the antibiotic tetracycline resulted in substantial clinical improvements within 24 hours. Interestingly, chronic cases were not detected throughout the course of this research.

Differential Diagnostics

The paper concludes by emphasizing the necessity to distinguish equine ehrlichiosis from other diseases that present similar clinical signs. These include encephalitis, liver disease, purpura hemorrhagica, equine infectious anemia, and equine viral arteritis.

Cite This Article

APA
Madigan JE, Gribble D. (1987). Equine ehrlichiosis in northern California: 49 cases (1968-1981). J Am Vet Med Assoc, 190(4), 445-448.

Publication

ISSN: 0003-1488
NlmUniqueID: 7503067
Country: United States
Language: English
Volume: 190
Issue: 4
Pages: 445-448

Researcher Affiliations

Madigan, J E
    Gribble, D

      MeSH Terms

      • Animals
      • California
      • Ehrlichia / ultrastructure
      • Horse Diseases / epidemiology
      • Horses
      • Microscopy, Electron
      • Retrospective Studies
      • Rickettsiaceae Infections / epidemiology
      • Rickettsiaceae Infections / veterinary
      • Seasons

      Citations

      This article has been cited 34 times.
      1. Rule EK, Boyle AG, Stefanovski D, Anis E, Linton J, Lorello O. Transfer of naturally acquired specific passive immunity against Anaplasma phagocytophilum in foals in Southeastern Pennsylvania and Northern Maryland.. J Vet Intern Med 2023 Sep-Oct;37(5):1889-1892.
        doi: 10.1111/jvim.16812pubmed: 37515307google scholar: lookup
      2. Laamari A, Azzag N, Tennah S, Derdour SY, China B, Bouabdallah R, Ghalmi F. Seroprevalence of Antibodies Against Anaplasma Phagocytophilum and Borrelia Burgdorferi in Horses (Equus Caballus) from Northern Algeria.. J Vet Res 2020 Sep;64(3):413-419.
        doi: 10.2478/jvetres-2020-0045pubmed: 32984632google scholar: lookup
      3. Schu00e4fer I, Kohn B. Anaplasma phagocytophilum infection in cats: A literature review to raise clinical awareness.. J Feline Med Surg 2020 May;22(5):428-441.
        doi: 10.1177/1098612X20917600pubmed: 32326861google scholar: lookup
      4. Fouchu00e9 N, Graubner C, Lanz S, Schweighauser A, Francey T, Gerber V. Acute kidney injury due to Leptospira interrogans in 4 foals and use of renal replacement therapy with intermittent hemodiafiltration in 1 foal.. J Vet Intern Med 2020 Mar;34(2):1007-1012.
        doi: 10.1111/jvim.15713pubmed: 31999382google scholar: lookup
      5. Johns JL, Discipulo ML, Koehne AL, Moorhead KA, Nagamine CM. Influence of Genetic Background on Hematologic and Histopathologic Alterations during Acute Granulocytic Anaplasmosis in 129/SvEv and C57BL/6J Mice Lacking Type I and Type II Interferon Signaling.. Comp Med 2017 Mar 1;67(2):127-137.
        pubmed: 28381313
      6. Schvartz G, Epp T, Burgess HJ, Chilton NB, Pearl DL, Lohmann KL. Seroprevalence of equine granulocytic anaplasmosis and lyme borreliosis in Canada as determined by a point-of-care enzyme-linked immunosorbent assay (ELISA).. Can Vet J 2015 Jun;56(6):575-80.
        pubmed: 26028677
      7. Seidman D, Hebert KS, Truchan HK, Miller DP, Tegels BK, Marconi RT, Carlyon JA. Essential domains of Anaplasma phagocytophilum invasins utilized to infect mammalian host cells.. PLoS Pathog 2015 Feb;11(2):e1004669.
        doi: 10.1371/journal.ppat.1004669pubmed: 25658707google scholar: lookup
      8. Al-Khedery B, Barbet AF. Comparative Genomics Identifies a Potential Marker of Human-Virulent Anaplasma phagocytophilum.. Pathogens 2014 Jan 9;3(1):25-35.
        doi: 10.3390/pathogens3010025pubmed: 25437606google scholar: lookup
      9. Uehlinger FD, Clancey NP, Lofstedt J. Granulocytic anaplasmosis in a horse from Nova Scotia caused by infection with Anaplasma phagocytophilum.. Can Vet J 2011 May;52(5):537-40.
        pubmed: 22043078
      10. Johns JL, Borjesson DL. Downregulation of CXCL12 signaling and altered hematopoietic stem and progenitor cell trafficking in a murine model of acute Anaplasma phagocytophilum infection.. Innate Immun 2012 Jun;18(3):418-28.
        doi: 10.1177/1753425911413794pubmed: 21964802google scholar: lookup
      11. Davies RS, Madigan JE, Hodzic E, Borjesson DL, Dumler JS. Dexamethasone-induced cytokine changes associated with diminished disease severity in horses infected with Anaplasma phagocytophilum.. Clin Vaccine Immunol 2011 Nov;18(11):1962-8.
        doi: 10.1128/CVI.05034-11pubmed: 21880854google scholar: lookup
      12. Rikihisa Y. Mechanisms of obligatory intracellular infection with Anaplasma phagocytophilum.. Clin Microbiol Rev 2011 Jul;24(3):469-89.
        doi: 10.1128/CMR.00064-10pubmed: 21734244google scholar: lookup
      13. Johns JL, Macnamara KC, Walker NJ, Winslow GM, Borjesson DL. Infection with Anaplasma phagocytophilum induces multilineage alterations in hematopoietic progenitor cells and peripheral blood cells.. Infect Immun 2009 Sep;77(9):4070-80.
        doi: 10.1128/IAI.00570-09pubmed: 19564373google scholar: lookup
      14. Nelson CM, Herron MJ, Felsheim RF, Schloeder BR, Grindle SM, Chavez AO, Kurtti TJ, Munderloh UG. Whole genome transcription profiling of Anaplasma phagocytophilum in human and tick host cells by tiling array analysis.. BMC Genomics 2008 Jul 31;9:364.
        doi: 10.1186/1471-2164-9-364pubmed: 18671858google scholar: lookup
      15. Foley J, Nieto NC, Foley P, Teglas MB. Co-phylogenetic analysis of Anaplasma phagocytophilum and its vectors, Ixodes spp. ticks.. Exp Appl Acarol 2008 Aug;45(3-4):155-70.
        doi: 10.1007/s10493-008-9173-7pubmed: 18648997google scholar: lookup
      16. Teglas MB, Foley J. Differences in the transmissibility of two Anaplasma phagocytophilum strains by the North American tick vector species, Ixodes pacificus and Ixodes scapularis (Acari: Ixodidae).. Exp Appl Acarol 2006;38(1):47-58.
        doi: 10.1007/s10493-005-5293-5pubmed: 16550334google scholar: lookup
      17. Poitout FM, Shinozaki JK, Stockwell PJ, Holland CJ, Shukla SK. Genetic variants of Anaplasma phagocytophilum infecting dogs in Western Washington State.. J Clin Microbiol 2005 Feb;43(2):796-801.
        doi: 10.1128/JCM.43.2.796-801.2005pubmed: 15695682google scholar: lookup
      18. Lin Q, Rikihisa Y, Massung RF, Woldehiwet Z, Falco RC. Polymorphism and transcription at the p44-1/p44-18 genomic locus in Anaplasma phagocytophilum strains from diverse geographic regions.. Infect Immun 2004 Oct;72(10):5574-81.
      19. Scorpio DG, Caspersen K, Ogata H, Park J, Dumler JS. Restricted changes in major surface protein-2 (msp2) transcription after prolonged in vitro passage of Anaplasma phagocytophilum.. BMC Microbiol 2004 Jan 8;4:1.
        doi: 10.1186/1471-2180-4-1pubmed: 14713314google scholar: lookup
      20. Martin ME, Caspersen K, Dumler JS. Immunopathology and ehrlichial propagation are regulated by interferon-gamma and interleukin-10 in a murine model of human granulocytic ehrlichiosis.. Am J Pathol 2001 May;158(5):1881-8.
        doi: 10.1016/s0002-9440(10)64145-4pubmed: 11337387google scholar: lookup
      21. Munderloh UG, Jauron SD, Fingerle V, Leitritz L, Hayes SF, Hautman JM, Nelson CM, Huberty BW, Kurtti TJ, Ahlstrand GG, Greig B, Mellencamp MA, Goodman JL. Invasion and intracellular development of the human granulocytic ehrlichiosis agent in tick cell culture.. J Clin Microbiol 1999 Aug;37(8):2518-24.
      22. Pusterla N, Huder JB, Leutenegger CM, Braun U, Madigan JE, Lutz H. Quantitative real-time PCR for detection of members of the Ehrlichia phagocytophila genogroup in host animals and Ixodes ricinus ticks.. J Clin Microbiol 1999 May;37(5):1329-31.
      23. Comer JA, Nicholson WL, Olson JG, Childs JE. Serologic testing for human granulocytic ehrlichiosis at a national referral center.. J Clin Microbiol 1999 Mar;37(3):558-64.
        doi: 10.1128/JCM.37.3.558-564.1999pubmed: 9986812google scholar: lookup
      24. Reubel GH, Kimsey RB, Barlough JE, Madigan JE. Experimental transmission of Ehrlichia equi to horses through naturally infected ticks (Ixodes pacificus) from Northern California.. J Clin Microbiol 1998 Jul;36(7):2131-4.
      25. Storey JR, Doros-Richert LA, Gingrich-Baker C, Munroe K, Mather TN, Coughlin RT, Beltz GA, Murphy CI. Molecular cloning and sequencing of three granulocytic Ehrlichia genes encoding high-molecular-weight immunoreactive proteins.. Infect Immun 1998 Apr;66(4):1356-63.
      26. Barlough JE, Madigan JE, Kramer VL, Clover JR, Hui LT, Webb JP, Vredevoe LK. Ehrlichia phagocytophila genogroup rickettsiae in ixodid ticks from California collected in 1995 and 1996.. J Clin Microbiol 1997 Aug;35(8):2018-21.
      27. Yeh MT, Mather TN, Coughlin RT, Gingrich-Baker C, Sumner JW, Massung RF. Serologic and molecular detection of granulocytic ehrlichiosis in Rhode Island.. J Clin Microbiol 1997 Apr;35(4):944-7.
        doi: 10.1128/jcm.35.4.944-947.1997pubmed: 9157157google scholar: lookup
      28. Barlough JE, Madigan JE, Turoff DR, Clover JR, Shelly SM, Dumler JS. An Ehrlichia strain from a llama (Lama glama) and Llama-associated ticks (Ixodes pacificus).. J Clin Microbiol 1997 Apr;35(4):1005-7.
      29. Munderloh UG, Madigan JE, Dumler JS, Goodman JL, Hayes SF, Barlough JE, Nelson CM, Kurtti TJ. Isolation of the equine granulocytic ehrlichiosis agent, Ehrlichia equi, in tick cell culture.. J Clin Microbiol 1996 Mar;34(3):664-70.
        doi: 10.1128/jcm.34.3.664-670.1996pubmed: 8904434google scholar: lookup
      30. Engvall EO, Pettersson B, Persson M, Artursson K, Johansson KE. A 16S rRNA-based PCR assay for detection and identification of granulocytic Ehrlichia species in dogs, horses, and cattle.. J Clin Microbiol 1996 Sep;34(9):2170-4.
      31. Madigan JE, Barlough JE, Dumler JS, Schankman NS, DeRock E. Equine granulocytic ehrlichiosis in Connecticut caused by an agent resembling the human granulocytotropic ehrlichia.. J Clin Microbiol 1996 Feb;34(2):434-5.
        doi: 10.1128/jcm.34.2.434-435.1996pubmed: 8789032google scholar: lookup
      32. Berrington A, Moats R, Lester S. A case of Ehrlichia equi in an adult horse in British Columbia.. Can Vet J 1996 Mar;37(3):174-5.
        pubmed: 8681291
      33. Barlough JE, Madigan JE, DeRock E, Dumler JS, Bakken JS. Protection against Ehrlichia equi is conferred by prior infection with the human granulocytotropic Ehrlichia (HGE agent).. J Clin Microbiol 1995 Dec;33(12):3333-4.
      34. Rikihisa Y. The tribe Ehrlichieae and ehrlichial diseases.. Clin Microbiol Rev 1991 Jul;4(3):286-308.
        doi: 10.1128/CMR.4.3.286pubmed: 1889044google scholar: lookup