title: Serosurvey of horses with evidence of equine monocytic ehrlichiosis.
abstract: In August 1986, an extensive serosurvey for prevalence of IgG and IgM antibodies against Ehrlichia risticii, the causative agent of equine monocytic ehrlichiosis (EME), was performed at 2 Ohio racetracks, River Downs (RD) and Beulah Park (BP). Of 840 horses at RD and 574 at BP, 13 and 20%, respectively, were IgG antibody-positive (by indirect fluorescent antibody test results), with antibody titer ranging from 1:20 to 1:10,240. The titer observed at highest frequency at both racetracks was 1:80. A higher proportion of horses was ill at RD (operating during the summer months) than at BP (winter track). Of ill horses, 41% (24/58) at RD and 58% (11/19) at BP were seropositive. At RD, 70% (589/840) of all horses and 95% (102/107) of IgG seropositive horses had been stabled only at RD during the month prior to testing. Analysis of these sera by use of an ELISA to detect IgM antibody against E risticii antigen indicated that at RD, 42% (57/137) of the seropositive horses were IgM seropositive. At BP, 17% (20/120) of seropositive horses were IgM seropositive. The larger number of IgM seropositive horses at RD indicates that more horses were recently infected at RD than at BP (P = 0.0001). Therefore, at least half the seropositive horses at RD seemed to have acquired the infection at RD. These serosurvey data also indicate that at BP and RD, 78% (85/109) and 91% (111/122) of IgG seropositive horses, respectively, had subclinical infection. At less than or equal to 1:40 titer, there was no difference in seropositive rates between healthy and ill horses.(ABSTRACT TRUNCATED AT 250 WORDS)
authors: Department of Veterinary Pathobiology, College of Veterinary Medicine, Ohio State University, Columbus 43210.
authors: Y
authors: Y
authors: Rikihisa
authors: S M
authors: SM
authors: Reed
authors: R A
authors: RA
authors: Sams
authors: J C
authors: JC
authors: Gordon
authors: C I
authors: CI
authors: Pretzman
mesh_terms: D000367:Age Factors; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D004536:Ehrlichia / Q000276:immunology*; D005260:Female; D005455:Fluorescent Antibody Technique; D006734:Horse Diseases / Q000453:epidemiology*; D006736:Horses; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D008297:Male; D009820:Ohio / Q000453:epidemiology; D015995:Prevalence; D012288:Rickettsiaceae Infections / Q000453:epidemiology / Q000662:veterinary*
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D007075:Immunoglobulin M