Antibodies to Ehrlichia equi in dogs from the northeastern United States.

摘要

To determine whether dogs living in tick-infested areas of the northeastern United States had been exposed to E. equi, serum samples from 106 ill dogs and 12 healthy dogs from an area unaffected by E. equi or Borrelia burgdorferi were analysed. Antibodies to E. equi were detected by indirect fluorescent antibody staining methods and western blot analyses. 10 (9.4%) of the 106 sera from ill, privately owned dogs living in tick-infested areas of Connecticut and New York state had antibodies to E. equi. Titration end points ranged from 1:80 to 1:1280. Immunoblots revealed antibodies to proteins of E. equi having molecular masses of predominantly 29, 40, 44, 105, 120, and 160 kDa. There was good agreement between results of serological testing methods, but use of the human isolate (NCH-1 strain) in western blot analyses detected 2 additional seropositive dogs found to be negative by indirect fluorescent antibody staining methods with the MRK strain. It is suggested that dogs living in areas where Ixodes scapularis is abundant may be exposed to many pathogens, such as E. equi or B. burgdorferi and that, although mild or subclinical infections with E. equi may develop, ehrlichiosis should be considered in dogs with marked leukopenia, thrombocytopeniaor anaemia. It is concluded that laboratory diagnosis should include examinations for morulae in granulocytes or monocytes in addition to serological analyses.