Ehrlichia equi infection of horses from Minnesota and Wisconsin: detection of seroconversion and acute disease investigation.
Abstract: Equine granulocytic ehrlichiosis (EGE) is caused by infection with Ehrlichia equi. EGE has been reported primarily in northern California, where E equi is transmitted by the tick Ixodes pacificus. Reports of EGE and the emergence of human granulocytic ehrlichia in Minnesota prompted a seroprevalence study of E equi in horses of Minnesota and Wisconsin. Tick (Ixodes scapularis) endemic areas of Minnesota and Wisconsin were compared to nonendemic regions of Minnesota. Indirect fluorescent antibody was used to detect the presence of serum antibodies to E equi. Serum samples from healthy horses, 375 samples from I scapularis endemic counties, and 366 samples from nonendemic counties were screened at a 1:40 dilution. Results demonstrated a seroprevalence of 17.6% in endemic areas versus 3.8% in nonendemic areas. Ehrlichial DNA from 2 samples was successfully amplified by polymerase chain reaction and 919 base pairs were sequenced. The DNA sequence of 1 Minnesota/Wisconsin strain differed from the GenBank strain (M73223) of E equi at positions 84 and 886 and from the MRK strain of E equi at position 84, and was identical to the human granulocytic ehrlichiosis (HGE) agent. The 2nd Minnesota/Wisconsin strain was identical to the 1st with the exception of a substitution of "A" at position 453 that is not present in E phagocytophila, E equi, or HGE agent strain sequences. Based on the results of this study, we concluded that E equi is present and causes infection in horses in Minnesota and Wisconsin. The occurrence of infection is higher in tick endemic regions.
Publication Date: 2000-06-01 PubMed ID: 10830537DOI: 10.1892/0891-6640(2000)014<0252:eiohfm>2.3.co;2Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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The research article aims to investigate the prevalence and cause of Equine granulocytic ehrlichiosis (EGE) in horses in areas of Minnesota and Wisconsin, USA, known to have tick populations. It found these horses demonstrate a higher percentage of EGE, likely caused by a tick-transmitted infection, Ehrlichia equi.
Background of the Study
- Equine granulocytic ehrlichiosis (EGE) is a disease impacting horses, which is primarily caused by an infection known as Ehrlichia equi. This infection is generally transmitted by the Ixodes pacificus tick, prevalent in northern California.
- Because of reported cases of EGE in Minnesota and the emergence of human granulocytic ehrlichia, an allied disease affecting humans, the researchers decided to study the prevalence of E. equi in horses from Minnesota and Wisconsin.
Methodology
- The researchers compared horse populations in areas of Minnesota and Wisconsin known for Ixodes scapularis tick endemicity with regions in Minnesota where these ticks were not present.
- The team used an Indirect Fluorescent Antibody test to detect the presence of E. equi serum antibodies, and analyzed serum samples from healthy horses. Including both endemic and non-endemic regions, they evaluated 741 samples.
Results
- The results showed a noticeable difference between the two areas in terms of the presence of E. equi, with a 17.6% seroprevalence in endemic areas as opposed to 3.8% in non-endemic regions.
- Ehrlichial DNA, derived from two of the samples, was successfully amplified by a polymerase chain reaction. 919 base pairs were sequenced in each of these samples.
- The DNA sequences of the E. equi strains in the Wisconsin and Minnesota samples differed at two specific positions from the GenBank strain (a strain sequence already recorded in a genetic database called GenBank) and the MRK strain.
- One of the Minnesota/Wisconsin strains was found to be identical to the agent that causes human granulocytic ehrlichiosis.
Conclusion
- The study concludes that infection by Ehrlichia equi is present in horses in Wisconsin and Minnesota and is responsible for causing EGE in these areas. This is especially true in regions having higher tick populations.
Cite This Article
APA
Bullock PM, Ames TR, Robinson RA, Greig B, Mellencamp MA, Dumler JS.
(2000).
Ehrlichia equi infection of horses from Minnesota and Wisconsin: detection of seroconversion and acute disease investigation.
J Vet Intern Med, 14(3), 252-257.
https://doi.org/10.1892/0891-6640(2000)014<0252:eiohfm>2.3.co;2 Publication
Researcher Affiliations
- Department of Clinical and Population Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, USA. bullo003@tc.umn.edu
MeSH Terms
- Acute Disease
- Animals
- Antibodies, Bacterial / blood
- Base Sequence
- DNA, Bacterial / blood
- DNA, Bacterial / chemistry
- DNA, Ribosomal / chemistry
- Ehrlichia / genetics
- Ehrlichia / immunology
- Ehrlichiosis / epidemiology
- Ehrlichiosis / immunology
- Ehrlichiosis / veterinary
- Female
- Horse Diseases / epidemiology
- Horse Diseases / immunology
- Horse Diseases / microbiology
- Horses
- Humans
- Ixodes
- Male
- Minnesota / epidemiology
- Molecular Sequence Data
- Polymerase Chain Reaction / veterinary
- RNA, Bacterial / blood
- RNA, Ribosomal, 16S / genetics
- Sequence Alignment / veterinary
- Sequence Analysis, DNA / veterinary
- Seroepidemiologic Studies
- Tick Infestations / epidemiology
- Wisconsin / epidemiology
Grant Funding
- R01 AI 41213-01 / NIAID NIH HHS
Citations
This article has been cited 4 times.- 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.
- Burgess H, Chilton NB, Krakowetz CN, Williams C, Lohmann K. Granulocytic anaplasmosis in a horse from Saskatchewan.. Can Vet J 2012 Aug;53(8):886-8.
- M'ghirbi Y, Yaïch H, Ghorbel A, Bouattour A. Anaplasma phagocytophilum in horses and ticks in Tunisia.. Parasit Vectors 2012 Aug 30;5:180.
- 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.
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